Subject: [PATCH RFC v6 16/21] drm: panel: Add support for Himax HX8369A MIPI DSI panel

From: [email-masked] (Liu Ying)
Date: Tue, 30 Dec 2014 10:39:19 +0800

On 12/29/2014 06:50 PM, Andrzej Hajda wrote:
> On 12/29/2014 11:07 AM, Liu Ying wrote:
>> On 12/29/2014 05:09 PM, Andrzej Hajda wrote:
>>> On 12/29/2014 07:39 AM, Liu Ying wrote:
>>>> This patch adds support for Himax HX8369A MIPI DSI panel.
>>>>
>>>> Signed-off-by: Liu Ying <[email-masked]>
>>>> ---
>>>> v5->v6:
>>>>    * Make the checkpatch.pl script be happier.
>>>>    * Do not set the dsi channel number to be zero in probe(), because the MIPI DSI
>>>>      bus driver would set it.
>>>>
>>>> v4->v5:
>>>>    * Address Andrzej Hajda's comments.
>>>>    * Get the bs-gpios property instead of the bs[3:0]-gpios properties.
>>>>    * Implement error propagation for panel register configurations.
>>>>    * Other minor changes to improve the code quality.
>>>>
>>>> v3->v4:
>>>>    * Move the relevant dt-bindings to a separate patch to address Stefan
>>>>      Wahren's comment.
>>>>
>>>> v2->v3:
>>>>    * Sort the included header files alphabetically.
>>>>
>>>> v1->v2:
>>>>    * Address almost all comments from Thierry Reding.
>>>>    * Remove several DT properties as they can be implied by the compatible string.
>>>>    * Add the HIMAX/himax prefixes to the driver's Kconfig name and driver name.
>>>>    * Move the driver's Makefile entry place to sort the entries alphabetically.
>>>>    * Reuse several standard DCS functions instead of inventing wheels.
>>>>    * Move the panel resetting and power logics to the driver probe/remove stages.
>>>>      This may simplify panel prepare/unprepare hooks. The power consumption should
>>>>      not change a lot at DPMS since the panel enters sleep mode at that time.
>>>>    * Add the module author.
>>>>    * Other minor changes, such as coding style issues.
>>>>
>>>>    drivers/gpu/drm/panel/Kconfig               |   5 +
>>>>    drivers/gpu/drm/panel/Makefile              |   1 +
>>>>    drivers/gpu/drm/panel/panel-himax-hx8369a.c | 614 ++++++++++++++++++++++++++++
>>>>    3 files changed, 620 insertions(+)
>>>>    create mode 100644 drivers/gpu/drm/panel/panel-himax-hx8369a.c
>>>>
>>>> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
>>>> index 024e98e..81b0bf0 100644
>>>> --- a/drivers/gpu/drm/panel/Kconfig
>>>> +++ b/drivers/gpu/drm/panel/Kconfig
>>>> @@ -16,6 +16,11 @@ config DRM_PANEL_SIMPLE
>>>>    	  that it can be automatically turned off when the panel goes into a
>>>>    	  low power state.
>>>>
>>>> +config DRM_PANEL_HIMAX_HX8369A
>>>> +	tristate "Himax HX8369A panel"
>>>> +	depends on OF
>>>> +	select DRM_MIPI_DSI
>>>> +
>>>>    config DRM_PANEL_LD9040
>>>>    	tristate "LD9040 RGB/SPI panel"
>>>>    	depends on OF && SPI
>>>> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
>>>> index 4b2a043..d5dbe06 100644
>>>> --- a/drivers/gpu/drm/panel/Makefile
>>>> +++ b/drivers/gpu/drm/panel/Makefile
>>>> @@ -1,4 +1,5 @@
>>>>    obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
>>>> +obj-$(CONFIG_DRM_PANEL_HIMAX_HX8369A) += panel-himax-hx8369a.o
>>>>    obj-$(CONFIG_DRM_PANEL_LD9040) += panel-ld9040.o
>>>>    obj-$(CONFIG_DRM_PANEL_S6E8AA0) += panel-s6e8aa0.o
>>>>    obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
>>>> diff --git a/drivers/gpu/drm/panel/panel-himax-hx8369a.c b/drivers/gpu/drm/panel/panel-himax-hx8369a.c
>>>> new file mode 100644
>>>> index 0000000..eee36a7
>>>> --- /dev/null
>>>> +++ b/drivers/gpu/drm/panel/panel-himax-hx8369a.c
>>>> @@ -0,0 +1,614 @@
>>>> +/*
>>>> + * Himax HX8369A panel driver.
>>>> + *
>>>> + * Copyright (C) 2011-2014 Freescale Semiconductor, Inc.
>>>> + *
>>>> + * This program is free software; you can redistribute it and/or modify
>>>> + * it under the terms of the GNU General Public License version 2 as
>>>> + * published by the Free Software Foundation.
>>>> + *
>>>> + * This driver is based on Samsung s6e8aa0 panel driver.
>>>> + */
>>>> +
>>>> +#include <drm/drmP.h>
>>>> +#include <drm/drm_mipi_dsi.h>
>>>> +#include <drm/drm_panel.h>
>>>> +
>>>> +#include <linux/gpio/consumer.h>
>>>> +#include <linux/of_device.h>
>>>> +#include <linux/regulator/consumer.h>
>>>> +
>>>> +#include <video/mipi_display.h>
>>>> +#include <video/of_videomode.h>
>>>> +#include <video/videomode.h>
>>>> +
>>>> +#define WRDISBV		0x51
>>>> +#define WRCTRLD		0x53
>>>> +#define WRCABC		0x55
>>>> +#define SETPOWER	0xb1
>>>> +#define SETDISP		0xb2
>>>> +#define SETCYC		0xb4
>>>> +#define SETVCOM		0xb6
>>>> +#define SETEXTC		0xb9
>>>> +#define SETMIPI		0xba
>>>> +#define SETPANEL	0xcc
>>>> +#define SETGIP		0xd5
>>>> +#define SETGAMMA	0xe0
>>>> +
>>>> +#define HX8369A_MIN_BRIGHTNESS	0x00
>>>> +#define HX8369A_MAX_BRIGHTNESS	0xff
>>>> +
>>>> +enum hx8369a_mpu_interface {
>>>> +	HX8369A_DBI_TYPE_A_8BIT,
>>>> +	HX8369A_DBI_TYPE_A_9BIT,
>>>> +	HX8369A_DBI_TYPE_A_16BIT,
>>>> +	HX8369A_DBI_TYPE_A_18BIT,
>>>> +	HX8369A_DBI_TYPE_B_8BIT,
>>>> +	HX8369A_DBI_TYPE_B_9BIT,
>>>> +	HX8369A_DBI_TYPE_B_16BIT,
>>>> +	HX8369A_DBI_TYPE_B_18BIT,
>>>> +	HX8369A_DSI_CMD_MODE,
>>>> +	HX8369A_DBI_TYPE_B_24BIT,
>>>> +	HX8369A_DSI_VIDEO_MODE,
>>>> +	HX8369A_MDDI,
>>>> +	HX8369A_DPI_DBI_TYPE_C_OPT1,
>>>> +	HX8369A_DPI_DBI_TYPE_C_OPT2,
>>>> +	HX8369A_DPI_DBI_TYPE_C_OPT3
>>>> +};
>>>> +
>>>> +enum hx8369a_resolution {
>>>> +	HX8369A_RES_480_864,
>>>> +	HX8369A_RES_480_854,
>>>> +	HX8369A_RES_480_800,
>>>> +	HX8369A_RES_480_640,
>>>> +	HX8369A_RES_360_640,
>>>> +	HX8369A_RES_480_720,
>>>> +};
>>>> +
>>>> +struct hx8369a_panel_desc {
>>>> +	const struct drm_display_mode *mode;
>>>> +
>>>> +	/* ms */
>>>> +	unsigned int power_on_delay;
>>>> +	unsigned int reset_delay;
>>>> +
>>>> +	unsigned int dsi_lanes;
>>>> +};
>>>> +
>>>> +struct hx8369a {
>>>> +	struct device *dev;
>>>> +	struct drm_panel panel;
>>>> +
>>>> +	const struct hx8369a_panel_desc *pd;
>>>> +
>>>> +	struct regulator_bulk_data supplies[5];
>>>> +	struct gpio_desc *reset_gpio;
>>>> +	struct gpio_desc *bs_gpio[4];
>>>> +	u8 res_sel;
>>>> +};
>>>> +
>>>> +static inline struct hx8369a *panel_to_hx8369a(struct drm_panel *panel)
>>>> +{
>>>> +	return container_of(panel, struct hx8369a, panel);
>>>> +}
>>>> +
>>>> +static int hx8369a_dcs_write(struct hx8369a *ctx, const char *func,
>>>> +			     const void *data, size_t len)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	ssize_t ret;
>>>> +
>>>> +	ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
>>>> +	if (ret < 0) {
>>>> +		dev_err(ctx->dev, "%s failed: %d\n", func, ret);
>>>> +		return ret;
>>>> +	}
>>>> +	return 0;
>>> Nitpick. You can replace 4 lines above with:
>>>       if (ret < 0)
>>>           dev_err(ctx->dev, "%s failed: %d\n", func, ret);
>>>       return ret;
>> I'll do that.
>>
>>>> +}
>>>> +
>>>> +#define hx8369a_dcs_write_seq(ctx, seq...) \
>>>> +({ \
>>>> +	const u8 d[] = { seq }; \
>>>> +	BUILD_BUG_ON_MSG(ARRAY_SIZE(d) > 64, \
>>>> +			 "DCS sequence too big for stack"); \
>>>> +	hx8369a_dcs_write(ctx, __func__, d, ARRAY_SIZE(d)); \
>>>> +})
>>>> +
>>>> +#define hx8369a_dcs_write_seq_static(ctx, seq...) \
>>>> +({ \
>>>> +	static const u8 d[] = { seq }; \
>>>> +	hx8369a_dcs_write(ctx, __func__, d, ARRAY_SIZE(d)); \
>>>> +})
>>>> +
>>>> +static int hx8369a_dsi_set_display_related_register(struct hx8369a *ctx)
>>>> +{
>>>> +	u8 sec_p = (ctx->res_sel << 4) | 0x03;
>>>> +
>>>> +	return hx8369a_dcs_write_seq(ctx, SETDISP, 0x00, sec_p, 0x03,
>>>> +			   0x03, 0x70, 0x00, 0xff, 0x00, 0x00, 0x00,
>>>> +			   0x00, 0x03, 0x03, 0x00, 0x01);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_display_waveform_cycle(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETCYC, 0x00, 0x1d,
>>>> +					0x5f, 0x0e, 0x06);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_gip(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETGIP, 0x00, 0x04,
>>>> +				 0x03, 0x00, 0x01, 0x05, 0x1c, 0x70,
>>>> +				 0x01, 0x03, 0x00, 0x00, 0x40, 0x06,
>>>> +				 0x51, 0x07, 0x00, 0x00, 0x41, 0x06,
>>>> +				 0x50, 0x07, 0x07, 0x0f, 0x04);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_power(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETPOWER, 0x01, 0x00,
>>>> +				   0x34, 0x06, 0x00, 0x0f, 0x0f, 0x2a,
>>>> +				   0x32, 0x3f, 0x3f, 0x07, 0x3a, 0x01,
>>>> +				   0xe6, 0xe6, 0xe6, 0xe6, 0xe6);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_vcom_voltage(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETVCOM, 0x56, 0x56);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_panel(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETPANEL, 0x02);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_gamma_curve(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETGAMMA, 0x00, 0x1d,
>>>> +				   0x22, 0x38, 0x3d, 0x3f, 0x2e, 0x4a,
>>>> +				   0x06, 0x0d, 0x0f, 0x13, 0x15, 0x13,
>>>> +				   0x16, 0x10, 0x19, 0x00, 0x1d, 0x22,
>>>> +				   0x38, 0x3d, 0x3f, 0x2e, 0x4a, 0x06,
>>>> +				   0x0d, 0x0f, 0x13, 0x15, 0x13, 0x16,
>>>> +				   0x10, 0x19);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_mipi(struct hx8369a *ctx)
>>>> +{
>>>> +	u8 eleventh_p = ctx->pd->dsi_lanes == 2 ? 0x11 : 0x10;
>>>> +
>>>> +	return hx8369a_dcs_write_seq(ctx, SETMIPI, 0x00, 0xa0, 0xc6,
>>>> +				 0x00, 0x0a, 0x00, 0x10, 0x30, 0x6f,
>>>> +				 0x02, eleventh_p, 0x18, 0x40);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_interface_pixel_fomat(struct hx8369a *ctx)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	u8 format;
>>>> +	int ret;
>>>> +
>>>> +	switch (dsi->format) {
>>>> +	case MIPI_DSI_FMT_RGB888:
>>>> +	case MIPI_DSI_FMT_RGB666:
>>>> +		format = 0x77;
>>>> +		break;
>>>> +	case MIPI_DSI_FMT_RGB565:
>>>> +		format = 0x55;
>>>> +		break;
>>>> +	case MIPI_DSI_FMT_RGB666_PACKED:
>>>> +		format = 0x66;
>>>> +		break;
>>>> +	default:
>>>> +		dev_err(ctx->dev, "unsupported DSI pixel format\n");
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>> +	ret = mipi_dsi_dcs_set_pixel_format(dsi, format);
>>>> +	if (ret < 0)
>>>> +		dev_err(ctx->dev, "%s failed: %d\n", __func__, ret);
>>>> +	return ret;
>>>> +}
>>> This functions could be also DSI helper, it is not specific to this panel,
>>> but it is just a suggestion.
>> Any documentation can reflect this could be a common DSI helper,
>> maybe the MIPI DSI spec?
>> I wrote this function by taking the HX8369A panel data sheet as a
>> reference.
>
> MIPI DSI specification describes MIPI_DSI_FMT_* values and
> MIPI DCS specification describes 'format' values (ie. 0x77, 0x55, 0x66).
> For reference please look for phrase "Table 6 Interface Pixel Formats" in
> MIPI DCS specification (or in google :) ).

Now, I find the table 6 you mentioned.
I called the common DSI helper mipi_dsi_dcs_set_pixel_format() to set
the format.  It seems that the helper gives specific drivers the
flexibility to provide the parameter 'format' and this driver uses the
flexibility to set the parameter to be 0x77/0x66/0x55.
I see the Sharp lq101r1sx01 panel driver calls the helper as well.
It sets the parameter 'format' to be MIPI_DSI_PIXEL_FMT_24BIT which is
defined as 0x7.
I think the Sharp panel supports the DBI interface only, perhaps.
The Himax HX9369A panel supports both the DPI and the DBI interfaces,
thus, this driver sets D[6:4] and D[2:0] to be 0x7 - finally 0x77.

So, basically, I prefer not to add another DSI helper to set the pixel
format in this patch set.  Thanks for your suggestion anyway.

>
>>
>>>> +
>>>> +static int hx8369a_dsi_set_column_address(struct hx8369a *ctx)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	const struct drm_display_mode *mode = ctx->pd->mode;
>>>> +	int ret;
>>>> +
>>>> +	ret = mipi_dsi_dcs_set_column_address(dsi, 0, mode->hdisplay - 1);
>>>> +	if (ret < 0)
>>>> +		dev_err(ctx->dev, "%s failed: %d\n", __func__, ret);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_page_address(struct hx8369a *ctx)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	const struct drm_display_mode *mode = ctx->pd->mode;
>>>> +	int ret;
>>>> +
>>>> +	ret = mipi_dsi_dcs_set_page_address(dsi, 0, mode->vdisplay - 1);
>>>> +	if (ret < 0)
>>>> +		dev_err(ctx->dev, "%s failed: %d\n", __func__, ret);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_write_display_brightness(struct hx8369a *ctx,
>>>> +						u8 brightness)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq(ctx, WRDISBV, brightness);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_write_cabc(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, WRCABC, 0x01);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_write_control_display(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, WRCTRLD, 0x24);
>>>> +}
>>>> +
>>>> +#define hx8369a_dsi_init_helper(ctx, ret, name) \
>>>> +({ \
>>>> +	ret = hx8369a_dsi_##name(ctx); \
>>>> +	if (ret < 0) \
>>>> +		return ret; \
>>>> +})
>>> Yeah, another hack to get rid of redundant code :)
>>> Two ugly things here: ## and return from macro.
>>>
>>>> +
>>>> +static int hx8369a_dsi_panel_init(struct hx8369a *ctx)
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_display_related_register);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_display_waveform_cycle);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_gip);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_power);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_vcom_voltage);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_panel);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_gamma_curve);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_mipi);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_interface_pixel_fomat);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_column_address);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, set_page_address);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, write_cabc);
>>>> +	hx8369a_dsi_init_helper(ctx, ret, write_control_display);
>>> Maybe it would be better to replace the hack above with something like:
>>> {
>>>       int (*)(struct hx8369a *ctx) funcs[] = {
>>>           hx8369a_dsi_set_display_related_register,
>>>           hx8369a_dsi_set_display_waveform_cycle,
>>>           ...
>>>        };
>>>       int ret, i;
>>>
>>>       for (i = 0; i < ARRAY_SIZE(funcs); ++i) {
>>>           ret = funcs[i](ctx);
>>>           if (ret)
>>>               return ret;
>>>       }
>> I'll change to use this.  Thanks.
>>
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_extension_command(struct hx8369a *ctx)
>>>> +{
>>>> +	return hx8369a_dcs_write_seq_static(ctx, SETEXTC, 0xff, 0x83, 0x69);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_maximum_return_packet_size(struct hx8369a *ctx,
>>>> +						      u16 size)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	int ret;
>>>> +
>>>> +	ret = mipi_dsi_set_maximum_return_packet_size(dsi, size);
>>>> +	if (ret < 0)
>>>> +		dev_err(ctx->dev,
>>>> +			"error %d setting maximum return packet size to %d\n",
>>>> +			ret, size);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_set_sequence(struct hx8369a *ctx)
>>>> +{
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	int ret;
>>>> +
>>>> +	ret = hx8369a_dsi_set_extension_command(ctx);
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +
>>>> +	ret = hx8369a_dsi_set_maximum_return_packet_size(ctx, 4);
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +
>>>> +	ret = hx8369a_dsi_panel_init(ctx);
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +
>>>> +	ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
>>>> +	if (ret < 0) {
>>>> +		dev_err(ctx->dev, "failed to exit sleep mode: %d\n", ret);
>>>> +		goto out;
>>>> +	}
>>>> +
>>>> +	ret = mipi_dsi_dcs_set_display_on(dsi);
>>>> +	if (ret < 0) {
>>>> +		dev_err(ctx->dev, "failed to set display on: %d\n", ret);
>>>> +		goto out;
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * It's necessary to wait 120msec after sending the Sleep Out
>>>> +	 * command before Sleep In command can be sent, according to
>>>> +	 * the HX8369A data sheet.
>>>> +	 */
>>>> +	msleep(120);
>>>> +out:
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_disable(struct drm_panel *panel)
>>>> +{
>>>> +	struct hx8369a *ctx = panel_to_hx8369a(panel);
>>>> +
>>>> +	return hx8369a_dsi_write_display_brightness(ctx,
>>>> +						HX8369A_MIN_BRIGHTNESS);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_unprepare(struct drm_panel *panel)
>>>> +{
>>>> +	struct hx8369a *ctx = panel_to_hx8369a(panel);
>>>> +	struct mipi_dsi_device *dsi = to_mipi_dsi_device(ctx->dev);
>>>> +	int ret;
>>>> +
>>>> +	ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
>>>> +	if (ret < 0) {
>>>> +		dev_err(ctx->dev, "failed to enter sleep mode: %d\n", ret);
>>>> +		goto out;
>>>> +	}
>>>> +
>>>> +	ret = mipi_dsi_dcs_set_display_off(dsi);
>>>> +	if (ret < 0) {
>>>> +		dev_err(ctx->dev, "failed to set display off: %d\n", ret);
>>>> +		goto out;
>>>> +	}
>>>> +
>>>> +	/*
>>>> +	 * This is to allow time for the supply voltages and clock
>>>> +	 * circuits to stablize, according to the HX8369A data sheet.
>>>> +	 */
>>>> +	msleep(5);
>>>> +out:
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_prepare(struct drm_panel *panel)
>>>> +{
>>>> +	struct hx8369a *ctx = panel_to_hx8369a(panel);
>>>> +
>>>> +	return hx8369a_dsi_set_sequence(ctx);
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_enable(struct drm_panel *panel)
>>>> +{
>>>> +	struct hx8369a *ctx = panel_to_hx8369a(panel);
>>>> +
>>>> +	return hx8369a_dsi_write_display_brightness(ctx,
>>>> +						HX8369A_MAX_BRIGHTNESS);
>>>> +}
>>>> +
>>>> +static int hx8369a_get_modes(struct drm_panel *panel)
>>>> +{
>>>> +	struct drm_connector *connector = panel->connector;
>>>> +	struct drm_device *drm = panel->drm;
>>>> +	struct hx8369a *ctx = panel_to_hx8369a(panel);
>>>> +	struct drm_display_mode *mode;
>>>> +	const struct drm_display_mode *m = ctx->pd->mode;
>>>> +
>>>> +	mode = drm_mode_duplicate(drm, m);
>>>> +	if (!mode) {
>>>> +		dev_err(drm->dev, "failed to add mode %ux%u@%u\n",
>>>> +			m->hdisplay, m->vdisplay, m->vrefresh);
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	drm_mode_set_name(mode);
>>>> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
>>>> +
>>>> +	connector->display_info.bpc = 8;
>>>> +	connector->display_info.width_mm = mode->width_mm;
>>>> +	connector->display_info.height_mm = mode->height_mm;
>>>> +
>>>> +	drm_mode_probed_add(connector, mode);
>>>> +
>>>> +	return 1;
>>>> +}
>>>> +
>>>> +static const struct drm_panel_funcs hx8369a_dsi_drm_funcs = {
>>>> +	.disable = hx8369a_dsi_disable,
>>>> +	.unprepare = hx8369a_dsi_unprepare,
>>>> +	.prepare = hx8369a_dsi_prepare,
>>>> +	.enable = hx8369a_dsi_enable,
>>>> +	.get_modes = hx8369a_get_modes,
>>>> +};
>>>> +
>>>> +static int hx8369a_power_on(struct hx8369a *ctx)
>>>> +{
>>>> +	int ret;
>>>> +
>>>> +	ret = regulator_bulk_enable(ARRAY_SIZE(ctx->supplies), ctx->supplies);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>> +
>>>> +	msleep(ctx->pd->power_on_delay);
>>>> +
>>>> +	gpiod_set_value(ctx->reset_gpio, 1);
>>>> +	usleep_range(50, 60);
>>>> +	gpiod_set_value(ctx->reset_gpio, 0);
>>>> +
>>>> +	msleep(ctx->pd->reset_delay);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int hx8369a_power_off(struct hx8369a *ctx)
>>>> +{
>>>> +	return regulator_bulk_disable(ARRAY_SIZE(ctx->supplies),
>>>> +				      ctx->supplies);
>>>> +}
>>>> +
>>>> +static void hx8369a_vm_to_res_sel(struct hx8369a *ctx)
>>>> +{
>>>> +	const struct drm_display_mode *mode = ctx->pd->mode;
>>>> +
>>>> +	switch (mode->hdisplay) {
>>>> +	case 480:
>>>> +		switch (mode->vdisplay) {
>>>> +		case 864:
>>>> +			ctx->res_sel = HX8369A_RES_480_864;
>>>> +			break;
>>>> +		case 854:
>>>> +			ctx->res_sel = HX8369A_RES_480_854;
>>>> +			break;
>>>> +		case 800:
>>>> +			ctx->res_sel = HX8369A_RES_480_800;
>>>> +			break;
>>>> +		case 640:
>>>> +			ctx->res_sel = HX8369A_RES_480_640;
>>>> +			break;
>>>> +		case 720:
>>>> +			ctx->res_sel = HX8369A_RES_480_720;
>>>> +			break;
>>>> +		default:
>>>> +			break;
>>>> +		}
>>>> +		break;
>>>> +	case 360:
>>>> +		if (mode->vdisplay == 640)
>>>> +			ctx->res_sel = HX8369A_RES_360_640;
>>>> +		break;
>>>> +	default:
>>>> +		break;
>>>> +	}
>>>> +}
>>>> +
>>>> +static const struct drm_display_mode truly_tft480800_16_e_mode = {
>>>> +	.clock = 26400,
>>>> +	.hdisplay = 480,
>>>> +	.hsync_start = 480 + 8,
>>>> +	.hsync_end = 480 + 8 + 8,
>>>> +	.htotal = 480 + 8 + 8 + 8,
>>>> +	.vdisplay = 800,
>>>> +	.vsync_start = 800 + 6,
>>>> +	.vsync_end = 800 + 6 + 6,
>>>> +	.vtotal = 800 + 6 + 6 + 6,
>>>> +	.vrefresh = 60,
>>>> +	.width_mm = 45,
>>>> +	.height_mm = 76,
>>>> +};
>>>> +
>>>> +static const struct hx8369a_panel_desc truly_tft480800_16_e_dsi = {
>>>> +	.mode = &truly_tft480800_16_e_mode,
>>>> +	.power_on_delay = 10,
>>>> +	.reset_delay = 10,
>>>> +	.dsi_lanes = 2,
>>>> +};
>>>> +
>>>> +static const struct of_device_id hx8369a_dsi_of_match[] = {
>>>> +	{
>>>> +		.compatible = "truly,tft480800-16-e-dsi",
>>>> +		.data = &truly_tft480800_16_e_dsi,
>>>> +	}, {
>>>> +		/* sentinel */
>>>> +	},
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, hx8369a_dsi_of_match);
>>>> +
>>>> +static int hx8369a_dsi_probe(struct mipi_dsi_device *dsi)
>>>> +{
>>>> +	struct device *dev = &dsi->dev;
>>>> +	const struct of_device_id *of_id =
>>>> +			of_match_device(hx8369a_dsi_of_match, dev);
>>>> +	struct hx8369a *ctx;
>>>> +	int ret, i;
>>>> +
>>>> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>>>> +	if (!ctx)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	ctx->dev = dev;
>>>> +
>>>> +	if (of_id) {
>>>> +		ctx->pd = of_id->data;
>>>> +	} else {
>>>> +		dev_err(dev, "cannot find compatible device\n");
>>>> +		return -ENODEV;
>>>> +	}
>>>> +
>>>> +	hx8369a_vm_to_res_sel(ctx);
>>>> +
>>>> +	ctx->supplies[0].supply = "vdd1";
>>>> +	ctx->supplies[1].supply = "vdd2";
>>>> +	ctx->supplies[2].supply = "vdd3";
>>>> +	ctx->supplies[3].supply = "dsi-vcc";
>>>> +	ctx->supplies[4].supply = "vpp";
>>>> +	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(ctx->supplies),
>>>> +				      ctx->supplies);
>>>> +	if (ret < 0) {
>>>> +		dev_info(dev, "failed to get regulators: %d\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	ctx->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>>>> +	if (IS_ERR(ctx->reset_gpio)) {
>>>> +		dev_info(dev, "cannot get reset-gpios %ld\n",
>>>> +			 PTR_ERR(ctx->reset_gpio));
>>>> +		return PTR_ERR(ctx->reset_gpio);
>>>> +	}
>>>> +
>>>> +	for (i = 0; i < 4; i++) {
>>>> +		ctx->bs_gpio[i] = devm_gpiod_get_index(dev, "bs", i,
>>>> +							GPIOD_OUT_HIGH);
>>>> +		if (!IS_ERR_OR_NULL(ctx->bs_gpio[i]))
>>>> +			dev_dbg(dev, "bs%d-gpio is configured\n", i);
>>> Are you sure you want to continue probe on error during getting gpios?
>> There could be holes in the gpio list as mentioned in [1].
>> For this panel, the potential holes mean that the relevant
>> gpios are not controlled by the driver but only by the
>> hardware.
>>
>> Perhaps, I need to handle the error case.
>> I tried to implement it in the following way.
>>
>> ctx->bs_gpio[i] = devm_gpiod_get_index(dev, "bs", i,
>>                                          GPIOD_OUT_HIGH);
>> if (!IS_ERR_OR_NULL(ctx->bs_gpio[i])) {
>>       dev_dbg(dev, "bs%d-gpio is configured\n", i);
>> } else if (IS_ERR(ctx->bs_gpio[i])) {
>>       dev_info(dev, "failed to get bs%d-gpio\n", i);
>>       return PTR_ERR(ctx->bs_gpio[i]);
>> }
>>
>> But, I get this in dmesg.  Any idea?
>> [    1.625634] panel-hx8369a-dsi 21e0000.mipi.0: failed to get bs0-gpio
>> [    1.633060] panel-hx8369a-dsi: probe of 21e0000.mipi.0 failed with
>> error -2
>
> I guess you should use devm_gpiod_get_index_optional .

You are right.  Thanks.

Regards,
Liu Ying

>
> Regards
> Andrzej
>
>>
>> [1] Documentation/devicetree/bindings/gpio/gpio.txt.
>>
>> Regards,
>>
>> Liu Ying
>>
>>> After addressing above comments you can add:
>>>
>>> Reviewed-by: Andrzej Hajda <[email-masked]>
>>>
>>>
>>>
>>> Regards
>>> Andrzej
>>>
>>>
>>>> +	}
>>>> +
>>>> +	ret = hx8369a_power_on(ctx);
>>>> +	if (ret < 0) {
>>>> +		dev_err(dev, "cannot power on\n");
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	drm_panel_init(&ctx->panel);
>>>> +	ctx->panel.dev = dev;
>>>> +	ctx->panel.funcs = &hx8369a_dsi_drm_funcs;
>>>> +
>>>> +	ret = drm_panel_add(&ctx->panel);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>> +
>>>> +	mipi_dsi_set_drvdata(dsi, ctx);
>>>> +
>>>> +	dsi->lanes = ctx->pd->dsi_lanes;
>>>> +	dsi->format = MIPI_DSI_FMT_RGB888;
>>>> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO |
>>>> +			  MIPI_DSI_MODE_VIDEO_BURST |
>>>> +			  MIPI_DSI_MODE_VIDEO_SYNC_PULSE;
>>>> +	ret = mipi_dsi_attach(dsi);
>>>> +	if (ret < 0)
>>>> +		drm_panel_remove(&ctx->panel);
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hx8369a_dsi_remove(struct mipi_dsi_device *dsi)
>>>> +{
>>>> +	struct hx8369a *ctx = mipi_dsi_get_drvdata(dsi);
>>>> +
>>>> +	mipi_dsi_detach(dsi);
>>>> +	drm_panel_remove(&ctx->panel);
>>>> +	return hx8369a_power_off(ctx);
>>>> +}
>>>> +
>>>> +static struct mipi_dsi_driver hx8369a_dsi_driver = {
>>>> +	.probe = hx8369a_dsi_probe,
>>>> +	.remove = hx8369a_dsi_remove,
>>>> +	.driver = {
>>>> +		.name = "panel-hx8369a-dsi",
>>>> +		.of_match_table = hx8369a_dsi_of_match,
>>>> +	},
>>>> +};
>>>> +module_mipi_dsi_driver(hx8369a_dsi_driver);
>>>> +
>>>> +MODULE_DESCRIPTION("Himax HX8369A panel driver");
>>>> +MODULE_AUTHOR("Liu Ying <[email-masked]>");
>>>> +MODULE_LICENSE("GPL v2");
>