Re: [PATCH] Input: ili210x - Fix reset timing

[Marek Vasut <marex@denx.de>]

On 5/18/22 21:09, Dmitry Torokhov wrote:
> On Wed, May 18, 2022 at 06:34:30PM +0200, Marek Vasut wrote:
>> According to Ilitek "231x & ILI251x Programming Guide" Version: 2.30
>> "2.1. Power Sequence", "T4 Chip Reset and discharge time" is minimum
>> 10ms and "T2 Chip initial time" is maximum 150ms. Adjust the reset
>> timings such that T4 is 15ms and T2 is 160ms to fit those figures.
>>
>> This prevents sporadic touch controller start up failures when some
>> systems with at least ILI251x controller boot, without this patch
>> the systems sometimes fail to communicate with the touch controller.
>>
>> Fixes: 201f3c803544c ("Input: ili210x - add reset GPIO support")
>> Signed-off-by: Marek Vasut <marex@denx.de>
>> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>> ---
>>   drivers/input/touchscreen/ili210x.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/input/touchscreen/ili210x.c b/drivers/input/touchscreen/ili210x.c
>> index 2bd407d86bae5..131cb648a82ae 100644
>> --- a/drivers/input/touchscreen/ili210x.c
>> +++ b/drivers/input/touchscreen/ili210x.c
>> @@ -951,9 +951,9 @@ static int ili210x_i2c_probe(struct i2c_client *client,
>>   		if (error)
>>   			return error;
>>   
>> -		usleep_range(50, 100);
>> +		msleep(15);
> 
> WARNING: msleep < 20ms can sleep for up to 20ms; see
> Documentation/timers/timers-howto.rst
> #38: FILE: drivers/input/touchscreen/ili210x.c:954:
> +               msleep(15);

Sigh, yes, fixed in V2 to be 12..15ms .

> Should this be usleep_range(10000, 15000) like in
> ili251x_hardware_reset()? Actually, should we adopt
> ili251x_hardware_reset() to be used there?

I'll send a separate patch for that, it is indeed a good idea, but I 
think we should keep the fix as simple as possible for backporting ?