Re: [PATCHv2 1/2] ads7846: OMAP3: Removal of warnings backtrace in bootup

Igor Grinberg
2011-02-03T10:10:33Z

Hi,

On 02/03/11 11:48, Sourav Poddar wrote:

> gpio_pendown in ads7846_probe is not getting initalized (defaulted to 0)
> resulting in gpio_free to be called without a gpio_request. This
> results in the following backtrace in bootup.
>
> ------------[ 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 ]---
>
> Initializing gpio_pendown in ads7846_probe to -1 before
> ads7846_setup_pendown function removes the above backtrace
> warning.
>
> Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
> Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
> ---
> drivers/input/touchscreen/ads7846.c | 1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index 14ea54b..036f245 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -1221,6 +1221,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
> ts->input = input_dev;
> ts->vref_mv = pdata->vref_mv;
> ts->swap_xy = pdata->swap_xy;
> + ts->gpio_pendown = -1;

Wouldn't it be better putting this into ads7846_setup_pendown() function?
This will keep the whole gpio_pendown initialization code close together.
Something like:

if (pdata->get_pendown_state) {
<http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/input/touchscreen/ads7846.c;h=14ea54b78e4648b0ac8a3403440f6f5d120dfdd9;hb=HEAD#l954> ts->get_pendown_state = pdata->get_pendown_state;
ts->gpio_pendown = -1;
<http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/input/touchscreen/ads7846.c;h=14ea54b78e4648b0ac8a3403440f6f5d120dfdd9;hb=HEAD#l955> return 0;
<http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/input/touchscreen/ads7846.c;h=14ea54b78e4648b0ac8a3403440f6f5d120dfdd9;hb=HEAD#l956>}

Also, why don't we use -EINVAL for the invalid gpio number instead of -1 constant?

>
> mutex_init(&ts->lock);
> init_waitqueue_head(&ts->wait);

--
Regards,
Igor.