From: Guenter Roeck <linux@roeck-us•net>
To: Linus Walleij <linus.walleij@linaro•org>,
netdev@vger•kernel.org, "David S . Miller" <davem@davemloft•net>,
Steve Glendinning <steve.glendinning@smsc•com>
Cc: Jeremy Linton <jeremy.linton@arm•com>,
Kamlakant Patel <kamlakant.patel@broadcom•com>,
Pavel Fedin <p.fedin@samsung•com>
Subject: Re: [PATCH 2/3] net: smsc911x: request and deassert optional RESET GPIO
Date: Fri, 8 Jul 2016 06:52:55 -0700 [thread overview]
Message-ID: <577FB037.4070901@roeck-us.net> (raw)
In-Reply-To: <1467968852-6175-2-git-send-email-linus.walleij@linaro.org>
On 07/08/2016 02:07 AM, Linus Walleij wrote:
> On some systems (such as the Qualcomm APQ8060 Dragonboard) the
> RESET signal of the SMSC911x is not pulled up by a resistor but
> connected to a GPIO line, so that the operating system must
> explicitly deassert RESET before use.
>
> Support this in the SMSC911x driver so this ethernet connector
> can be used on such targets.
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro•org>
> ---
> drivers/net/ethernet/smsc/smsc911x.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c
> index 8af25563f627..125d58ac22bd 100644
> --- a/drivers/net/ethernet/smsc/smsc911x.c
> +++ b/drivers/net/ethernet/smsc/smsc911x.c
> @@ -62,6 +62,7 @@
> #include <linux/acpi.h>
> #include <linux/pm_runtime.h>
> #include <linux/property.h>
> +#include <linux/gpio/consumer.h>
>
> #include "smsc911x.h"
>
> @@ -149,6 +150,9 @@ struct smsc911x_data {
> /* regulators */
> struct regulator_bulk_data supplies[SMSC911X_NUM_SUPPLIES];
>
> + /* Reset GPIO */
> + struct gpio_desc *reset_gpiod;
> +
> /* clock */
> struct clk *clk;
> };
> @@ -440,6 +444,15 @@ static int smsc911x_request_resources(struct platform_device *pdev)
> netdev_err(ndev, "couldn't get regulators %d\n",
> ret);
>
> + /* Request optional RESET GPIO */
> + pdata->reset_gpiod = devm_gpiod_get(&pdev->dev, "reset",
> + GPIOD_OUT_HIGH);
> + /* Deassert the signal */
> + if (!IS_ERR(pdata->reset_gpiod)) {
This could return -EPROBE_DEFER, which should probably not be ignored.
It might be better to use devm_gpiod_get_optional(). If you pass GPIOD_OUT_LOW
as parameter to that function, it should take the chip out of reset immediately.
See drivers/i2c/muxes/i2c-mux-pca954x.c for an example with a similar use case.
Guenter
> + dev_info(&pdev->dev, "release reset\n");
> + gpiod_set_value(pdata->reset_gpiod, 0);
> + }
> +
> /* Request clock */
> pdata->clk = clk_get(&pdev->dev, NULL);
> if (IS_ERR(pdata->clk))
>
next prev parent reply other threads:[~2016-07-08 13:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-08 9:07 [PATCH 1/3] net: smsc911x: augment device tree bindings Linus Walleij
2016-07-08 9:07 ` [PATCH 2/3] net: smsc911x: request and deassert optional RESET GPIO Linus Walleij
2016-07-08 13:52 ` Guenter Roeck [this message]
2016-07-08 9:07 ` [PATCH 3/3] RFC: net: smsc911x: add wake-up event interrupt support Linus Walleij
2016-07-11 8:14 ` Tony Lindgren
2016-07-11 10:23 ` Sudeep Holla
2016-07-15 19:13 ` Florian Fainelli
2016-07-15 19:03 ` [PATCH 1/3] net: smsc911x: augment device tree bindings Rob Herring
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