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

Igor Grinberg
2011-02-03T10:17:55Z

Hi again,

On 02/03/11 12:10, Igor Grinberg wrote:

> 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>}

Sorry for the above links (this is embarrassing, but I've got played by my email client),
I meant of course:

if (pdata->get_pendown_state) {
ts->get_pendown_state = pdata->get_pendown_state;
ts->gpio_pendown = -1;
return 0;
}

>
> 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.