Re: [PATCH v3 2/2] Input: ads7846: use gpio_request_one to configure pendown_gpio

From: Igor Grinberg <grinberg@compulab.co.il>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Sourav Poddar <sourav.poddar@ti.com>,
	LW@karo-electronics.de, linux-omap@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-input@vger.kernel.org, gadiyar@ti.com, charu@ti.com,
	balbi@ti.com
Subject: Re: [PATCH v3 2/2] Input: ads7846: use gpio_request_one to configure pendown_gpio
Date: Fri, 04 Feb 2011 17:13:01 +0200	[thread overview]
Message-ID: <4D4C177D.1040605@compulab.co.il> (raw)
In-Reply-To: <20110203171953.GA13997@core.coreip.homeip.net>

Hi Dmitry,

On Thu, Feb 03, 2011 at 08:54:05AM -0800, Dmitry Torokhov wrote:
>> On Thu, Feb 03, 2011 at 08:51:46PM +0530, Sourav Poddar wrote:
>>> The ads7846 driver requests a gpio but does not currently
>>> configure it explicitly as an input. Use gpio_request_one
>>> to request and configure it at one shot.
>>>
>>> Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
>>> Cc: Dmitry Torokhov <dtor@mail.ru>
>> Will apply this one, the other one is a bit messy IMO, will have to
>> think about it.
>>
> Something like below should do I think.

Personally, I don't like the "if{}else if{}else{}" stuff and prefer spartan
programming techniques instead, but the "if-else" below still looks ok,
having a single success exit point is important and everybody is fine
with that approach - then I'm fine with it too.

Thanks for hopping in :)

>
> Dmitry
>
>
> Input: ads7846 - check proper condition when freeing gpio
>
> From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> When driver uses custom pendown detection method gpio_pendown is not
> set up and so we should not try to free it, otherwise we are presented
> with:
>
> ------------[ cut here ]------------
> WARNING: at drivers/gpio/gpiolib.c:1258 gpio_free+0x100/0x12c()
> Modules linked in:
> [<c0061208>] (unwind_backtrace+0x0/0xe4) from [<c0091f58>](warn_slowpath_common+0x4c/0x64)
> [<c0091f58>] (warn_slowpath_common+0x4c/0x64) from [<c0091f88>](warn_slowpath_null+0x18/0x1c)
> [<c0091f88>] (warn_slowpath_null+0x18/0x1c) from [<c024e610>](gpio_free+0x100/0x12c)
> [<c024e610>] (gpio_free+0x100/0x12c) from [<c03e9fbc>](ads7846_probe+0xa38/0xc5c)
> [<c03e9fbc>] (ads7846_probe+0xa38/0xc5c) from [<c02cff14>](spi_drv_probe+0x18/0x1c)
> [<c02cff14>] (spi_drv_probe+0x18/0x1c) from [<c028bca4>](driver_probe_device+0xc8/0x184)
> [<c028bca4>] (driver_probe_device+0xc8/0x184) from [<c028bdc8>](__driver_attach+0x68/0x8c)
> [<c028bdc8>] (__driver_attach+0x68/0x8c) from [<c028b4c8>](bus_for_each_dev+0x48/0x74)
> [<c028b4c8>] (bus_for_each_dev+0x48/0x74) from [<c028ae08>](bus_add_driver+0xa0/0x220)
> [<c028ae08>] (bus_add_driver+0xa0/0x220) from [<c028c0c0>](driver_register+0xa8/0x134)
> [<c028c0c0>] (driver_register+0xa8/0x134) from [<c0050550>](do_one_initcall+0xcc/0x1a4)
> [<c0050550>] (do_one_initcall+0xcc/0x1a4) from [<c00084e4>](kernel_init+0x14c/0x214)
> [<c00084e4>] (kernel_init+0x14c/0x214) from [<c005b494>](kernel_thread_exit+0x0/0x8)
> ---[ end trace 4053287f8a5ec18f ]---
>
> Also rearrange ads7846_setup_pendown() to have only one exit point
> returning success.
>
> Reported-by: Sourav Poddar <sourav.poddar@ti.com>
> Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
> ---
>
>  drivers/input/touchscreen/ads7846.c |   39 ++++++++++++++++++++---------------
>  1 files changed, 22 insertions(+), 17 deletions(-)
>
>
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index 0e9492d..b1217e1 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -946,30 +946,30 @@ static int __devinit ads7846_setup_pendown(struct spi_device *spi, struct ads784
>  	struct ads7846_platform_data *pdata = spi->dev.platform_data;
>  	int err;
>  
> -	/* REVISIT when the irq can be triggered active-low, or if for some
> +	/*
> +	 * REVISIT when the irq can be triggered active-low, or if for some
>  	 * reason the touchscreen isn't hooked up, we don't need to access
>  	 * the pendown state.
>  	 */
> -	if (!pdata->get_pendown_state && !gpio_is_valid(pdata->gpio_pendown)) {
> -		dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
> -		return -EINVAL;
> -	}
>  
>  	if (pdata->get_pendown_state) {
>  		ts->get_pendown_state = pdata->get_pendown_state;
> -		return 0;
> -	}
> +	} else if (gpio_is_valid(pdata->gpio_pendown)) {
> +
> +		err = gpio_request_one(pdata->gpio_pendown, GPIOF_DIR_IN,
> +							"ads7846_pendown");
> +		if (err) {
> +			dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
> +				pdata->gpio_pendown);
> +			return err;
> +		}
>  
> -	err = gpio_request_one(pdata->gpio_pendown, GPIOF_DIR_IN,
> -						"ads7846_pendown");
> -	if (err) {
> -		dev_err(&spi->dev, "failed to request pendown GPIO%d\n",
> -			pdata->gpio_pendown);
> -		return err;
> +		ts->gpio_pendown = pdata->gpio_pendown;
> +	} else {
> +		dev_err(&spi->dev, "no get_pendown_state nor gpio_pendown?\n");
> +		return -EINVAL;
>  	}
>  
> -	ts->gpio_pendown = pdata->gpio_pendown;
> -
>  	return 0;
>  }
>  
> @@ -1359,7 +1359,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
>   err_put_regulator:
>  	regulator_put(ts->reg);
>   err_free_gpio:
> -	if (ts->gpio_pendown != -1)
> +	if (!ts->get_pendown_state)
>  		gpio_free(ts->gpio_pendown);
>   err_cleanup_filter:
>  	if (ts->filter_cleanup)
> @@ -1389,8 +1389,13 @@ static int __devexit ads7846_remove(struct spi_device *spi)
>  	regulator_disable(ts->reg);
>  	regulator_put(ts->reg);
>  
> -	if (ts->gpio_pendown != -1)
> +	if (!ts->get_pendown_state) {
> +		/*
> +		 * If we are not using specialized pendown method we must
> +		 * have been relying on gpio we set up ourselves.
> +		 */
>  		gpio_free(ts->gpio_pendown);
> +	}
>  
>  	if (ts->filter_cleanup)
>  		ts->filter_cleanup(ts->filter_data);
>
>
>

-- 
Regards,
Igor.