Subject: Re: [PATCH 1/2] drm/arm: Factor out generic afbc helpers

From: Ayan Halder <[email-masked]>
Date: Mon, 21 Oct 2019 13:50:14 +0000

On Fri, Oct 11, 2019 at 01:18:10PM +0200, Andrzej Pietrasiewicz wrote:
> These are useful for other users of afbc, e.g. rockchip.
> 
> Signed-off-by: Andrzej Pietrasiewicz <[email-masked]>

Hi Andrzej,

Thanks a lot for doing this. Much appreciated. :)
It was on our TODO list for a long time.

I have cc-ed [email-masked], [email-masked] for
their comments as well.

> ---
>  drivers/gpu/drm/Kconfig          |   4 ++
>  drivers/gpu/drm/Makefile         |   1 +
>  drivers/gpu/drm/arm/Kconfig      |   1 +
>  drivers/gpu/drm/arm/malidp_drv.c |  58 ++--------------
>  drivers/gpu/drm/drm_afbc.c       | 114 +++++++++++++++++++++++++++++++
>  include/drm/drm_afbc.h           |  25 +++++++
>  6 files changed, 149 insertions(+), 54 deletions(-)
>  create mode 100644 drivers/gpu/drm/drm_afbc.c
>  create mode 100644 include/drm/drm_afbc.h
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 3c88420e3497..00e3f90557f4 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -195,6 +195,10 @@ config DRM_SCHED
>  	tristate
>  	depends on DRM
>  
> +config DRM_AFBC
> +	tristate
> +	depends on DRM
Adding a 'help' would be great here. Stealing the first line from
https://www.kernel.org/doc/html/latest/gpu/afbc.html

"AFBC is a proprietary lossless image compression protocol and format.
It provides fine-grained random access and minimizes the amount of
data transferred between IP blocks."

> +
>  source "drivers/gpu/drm/i2c/Kconfig"
>  
>  source "drivers/gpu/drm/arm/Kconfig"
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 9f0d2ee35794..55368b668355 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -31,6 +31,7 @@ drm-$(CONFIG_OF) += drm_of.o
>  drm-$(CONFIG_AGP) += drm_agpsupport.o
>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> +drm-$(CONFIG_DRM_AFBC) += drm_afbc.o
>  
>  drm_vram_helper-y := drm_gem_vram_helper.o \
>  		     drm_vram_helper_common.o \
> diff --git a/drivers/gpu/drm/arm/Kconfig b/drivers/gpu/drm/arm/Kconfig
> index a204103b3efb..25c3dc408cda 100644
> --- a/drivers/gpu/drm/arm/Kconfig
> +++ b/drivers/gpu/drm/arm/Kconfig
> @@ -29,6 +29,7 @@ config DRM_MALI_DISPLAY
>  	select DRM_KMS_HELPER
>  	select DRM_KMS_CMA_HELPER
>  	select DRM_GEM_CMA_HELPER
> +	select DRM_AFBC
>  	select VIDEOMODE_HELPERS
>  	help
>  	  Choose this option if you want to compile the ARM Mali Display
> diff --git a/drivers/gpu/drm/arm/malidp_drv.c b/drivers/gpu/drm/arm/malidp_drv.c
> index f25ec4382277..a67b69e08f63 100644
> --- a/drivers/gpu/drm/arm/malidp_drv.c
> +++ b/drivers/gpu/drm/arm/malidp_drv.c
> @@ -16,6 +16,7 @@
>  #include <linux/debugfs.h>
>  
>  #include <drm/drmP.h>
> +#include <drm/drm_afbc.h>
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_crtc.h>
> @@ -33,8 +34,6 @@
>  #include "malidp_hw.h"
>  
>  #define MALIDP_CONF_VALID_TIMEOUT	250
> -#define AFBC_HEADER_SIZE		16
> -#define AFBC_SUPERBLK_ALIGNMENT		128
>  
>  static void malidp_write_gamma_table(struct malidp_hw_device *hwdev,
>  				     u32 data[MALIDP_COEFFTAB_NUM_COEFFS])
> @@ -275,24 +274,8 @@ malidp_verify_afbc_framebuffer_caps(struct drm_device *dev,
>  					mode_cmd->modifier[0]) == false)
>  		return false;
>  
> -	if (mode_cmd->offsets[0] != 0) {
> -		DRM_DEBUG_KMS("AFBC buffers' plane offset should be 0\n");
> -		return false;
> -	}
> -
> -	switch (mode_cmd->modifier[0] & AFBC_SIZE_MASK) {
> -	case AFBC_SIZE_16X16:
> -		if ((mode_cmd->width % 16) || (mode_cmd->height % 16)) {
> -			DRM_DEBUG_KMS("AFBC buffers must be aligned to 16 pixels\n");
> -			return false;
> -		}
> -		break;
> -	default:
> -		DRM_DEBUG_KMS("Unsupported AFBC block size\n");
> -		return false;
> -	}
> -
> -	return true;
> +	return drm_afbc_check_offset(dev, mode_cmd) &&
> +	       drm_afbc_check_size_align(dev, mode_cmd);
>  }
>  
>  static bool
> @@ -300,53 +283,20 @@ malidp_verify_afbc_framebuffer_size(struct drm_device *dev,
>  				    struct drm_file *file,
>  				    const struct drm_mode_fb_cmd2 *mode_cmd)
>  {
> -	int n_superblocks = 0;
>  	const struct drm_format_info *info;
>  	struct drm_gem_object *objs = NULL;
> -	u32 afbc_superblock_size = 0, afbc_superblock_height = 0;
> -	u32 afbc_superblock_width = 0, afbc_size = 0;
>  	int bpp = 0;
>  
> -	switch (mode_cmd->modifier[0] & AFBC_SIZE_MASK) {
> -	case AFBC_SIZE_16X16:
> -		afbc_superblock_height = 16;
> -		afbc_superblock_width = 16;
> -		break;
> -	default:
> -		DRM_DEBUG_KMS("AFBC superblock size is not supported\n");
> -		return false;
> -	}
> -
>  	info = drm_get_format_info(dev, mode_cmd);
> -
> -	n_superblocks = (mode_cmd->width / afbc_superblock_width) *
> -		(mode_cmd->height / afbc_superblock_height);
> -
>  	bpp = malidp_format_get_bpp(info->format);
>  
> -	afbc_superblock_size = (bpp * afbc_superblock_width * afbc_superblock_height)
> -				/ BITS_PER_BYTE;
> -
> -	afbc_size = ALIGN(n_superblocks * AFBC_HEADER_SIZE, AFBC_SUPERBLK_ALIGNMENT);
> -	afbc_size += n_superblocks * ALIGN(afbc_superblock_size, AFBC_SUPERBLK_ALIGNMENT);
> -
> -	if ((mode_cmd->width * bpp) != (mode_cmd->pitches[0] * BITS_PER_BYTE)) {
> -		DRM_DEBUG_KMS("Invalid value of (pitch * BITS_PER_BYTE) (=%u) "
> -			      "should be same as width (=%u) * bpp (=%u)\n",
> -			      (mode_cmd->pitches[0] * BITS_PER_BYTE),
> -			      mode_cmd->width, bpp);
> -		return false;
> -	}
> -
>  	objs = drm_gem_object_lookup(file, mode_cmd->handles[0]);
>  	if (!objs) {
>  		DRM_DEBUG_KMS("Failed to lookup GEM object\n");
>  		return false;
>  	}
>  
> -	if (objs->size < afbc_size) {
> -		DRM_DEBUG_KMS("buffer size (%zu) too small for AFBC buffer size = %u\n",
> -			      objs->size, afbc_size);
> +	if (!drm_afbc_check_fb_size(dev, mode_cmd, objs, bpp)) {
>  		drm_gem_object_put_unlocked(objs);
>  		return false;
>  	}
Also can you do the code refactoring for komeda driver as well.
specifically komeda_fb_afbc_size_check(). I will let
[email-masked] and [email-masked] have their
opinion on this.

> diff --git a/drivers/gpu/drm/drm_afbc.c b/drivers/gpu/drm/drm_afbc.c
> new file mode 100644
> index 000000000000..3e8a9225fd2e
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_afbc.c
> @@ -0,0 +1,114 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * (C) 2019 Collabora Ltd.
> + *
> + * author: Andrzej Pietrasiewicz <[email-masked]>
> + *
> + */
> +#include <linux/module.h>
> +
> +#include <drm/drm_afbc.h>
> +#include <drm/drm_device.h>
> +#include <drm/drm_fourcc.h>
> +#include <drm/drm_gem.h>
> +#include <drm/drm_mode.h>
> +#include <drm/drm_print.h>
> +
> +#define AFBC_HEADER_SIZE		16
> +#define AFBC_SUPERBLK_ALIGNMENT		128
> +
> +bool drm_afbc_check_offset(struct drm_device *dev,
> +			   const struct drm_mode_fb_cmd2 *mode_cmd)
> +{
> +	if (mode_cmd->offsets[0] != 0) {
> +		DRM_DEBUG_KMS("AFBC buffers' plane offset should be 0\n");
> +		return false;
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(drm_afbc_check_offset);
> +
> +bool drm_afbc_check_size_align(struct drm_device *dev,
> +			       const struct drm_mode_fb_cmd2 *mode_cmd)
> +{
> +
> +	switch (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> +		if ((mode_cmd->width % 16) || (mode_cmd->height % 16)) {
> +			DRM_DEBUG_KMS(
> +				"AFBC buffer must be aligned to 16 pixels\n"
> +			);
> +			return false;
> +		}
> +		break;
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
> +		/* fall through */
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> +		/* fall through */
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> +		/* fall through */
> +	default:
> +		DRM_DEBUG_KMS("Unsupported AFBC block size\n");
> +		return false;
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL_GPL(drm_afbc_check_size_align);
> +
> +bool drm_afbc_check_fb_size(struct drm_device *dev,
> +			    const struct drm_mode_fb_cmd2 *mode_cmd,
> +			    struct drm_gem_object *objs, int bpp)
> +{
> +	int n_superblocks = 0;
> +	u32 afbc_superblock_size = 0, afbc_superblock_height = 0;
> +	u32 afbc_superblock_width = 0, afbc_size = 0;
> +
> +	switch (mode_cmd->modifier[0] & AFBC_FORMAT_MOD_BLOCK_SIZE_MASK) {
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_16x16:
> +		afbc_superblock_height = 16;
> +		afbc_superblock_width = 16;
> +		break;
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8:
Copying from
https://cgit.freedesktop.org/drm/drm-tip/tree/drivers/gpu/drm/arm/display/komeda/komeda_framebuffer.c#n60
                afbc_superblock_width = 32;
                afbc_superblock_height = 8;
> +		/* fall through */
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_64x4:
> +		/* fall through */
> +	case AFBC_FORMAT_MOD_BLOCK_SIZE_32x8_64x4:
> +		/* fall through */
> +	default:
> +		DRM_DEBUG_KMS("AFBC superblock size is not supported\n");
> +		return false;
> +	}
Can you combine the two switch - case confitions (from this function
and the one in drm_afbc_check_size_align()) and put it in a separate
function (say drm_afbc_get_superblock_dimensions()) of its own ?
This will help to avoid code repetition.

> +
> +	n_superblocks = (mode_cmd->width / afbc_superblock_width) *
> +		(mode_cmd->height / afbc_superblock_height);
> +
> +	afbc_superblock_size =
> +		(bpp * afbc_superblock_width * afbc_superblock_height)
> +			/ BITS_PER_BYTE;
> +
> +	afbc_size = ALIGN(n_superblocks * AFBC_HEADER_SIZE,
> +			  AFBC_SUPERBLK_ALIGNMENT);
> +	afbc_size += n_superblocks *
> +		ALIGN(afbc_superblock_size, AFBC_SUPERBLK_ALIGNMENT);
> +
> +	if ((mode_cmd->width * bpp) != (mode_cmd->pitches[0] * BITS_PER_BYTE)) {
> +		DRM_DEBUG_KMS("Invalid value of (pitch * BITS_PER_BYTE) (=%u) should be same as width (=%u) * bpp (=%u)\n",
> +			mode_cmd->pitches[0] * BITS_PER_BYTE,
> +			mode_cmd->width, bpp
> +		);
> +		return false;
> +	}
> +
> +	if (objs->size < afbc_size) {
> +		DRM_DEBUG_KMS("buffer size (%zu) too small for AFBC buffer size = %u\n",
> +			objs->size, afbc_size
> +		);
> +
> +		return false;
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_afbc_check_fb_size);
> diff --git a/include/drm/drm_afbc.h b/include/drm/drm_afbc.h
> new file mode 100644
> index 000000000000..ce39c850217b
> --- /dev/null
> +++ b/include/drm/drm_afbc.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * (C) 2019 Collabora Ltd.
> + *
> + * author: Andrzej Pietrasiewicz <[email-masked]>
> + *
> + */
> +#ifndef __DRM_AFBC_H__
> +#define __DRM_AFBC_H__
> +
> +struct drm_device;
> +struct drm_mode_fb_cmd2;
> +struct drm_gem_object;
> +
> +bool drm_afbc_check_offset(struct drm_device *dev,
> +			   const struct drm_mode_fb_cmd2 *mode_cmd);
> +
> +bool drm_afbc_check_size_align(struct drm_device *dev,
> +			       const struct drm_mode_fb_cmd2 *mode_cmd);
> +
> +bool drm_afbc_check_fb_size(struct drm_device *dev,
> +			    const struct drm_mode_fb_cmd2 *mode_cmd,
> +			    struct drm_gem_object *objs, int bpp);
> +
> +#endif /* __DRM_AFBC_H__ */
> --
> 2.17.1
> 
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