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

Poddar, Sourav
2011-02-03T11:00:29Z

On Thu, Feb 3, 2011 at 3:47 PM, Igor Grinberg <grinberg@compulab.co.il> wrote:
> 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;
> }
>

Yes we can do so .I initialise it at a place where other variables
where initialised.

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

I used -1 because conditional check done in probe ads7846_probe function
used this value.

err_free_gpio:
if (ts->gpio_pendown != -1)
gpio_free(ts->gpio_pendown);
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