[U-Boot] [PATCH v3 0/5] Add get_alt_function ops

[Michal Simek]

On 11.9.2018 13:12, Patrice CHOTARD wrote:
> Hi,
> 
> On 09/11/2018 12:24 PM, Michal Simek wrote:
>> Hi,
>>
>> On 11.9.2018 09:31, Patrice CHOTARD wrote:
>>> Hi Michal
>>>
>>> On 09/11/2018 07:51 AM, Michal Simek wrote:
>>>> On 10.9.2018 18:11, Patrice Chotard wrote:
>>>>>
>>>>> This series :
>>>>>   - Add new gpio ops get_alt_function
>>>>>   - Add get_function and get_alt_function support to stm32 gpio driver
>>>>>   - Add get_alt_function test
>>>>
>>>>
>>>> I went quickly over this series and TBH I am not getting what this is
>>>> for. It looks like that this is the part of pinmux.
>>>>
>>>> Can you please elaborate more what this is for?
>>>
>>> Currently, get_function callback returns the state of a gpio
>>> (GPIOF_INPUT, GPIOF_OUTPUT or GPIO_FUNC).
>>>
>>> If a pin's state is GPIO_FUNC, it's useful to know which alternate
>>> function is selected for debug purpose.
>>>
>>> As example, on STM32 SoCs, a pins can be configured as GPIO or also
>>> configured with up to 16 alternate function. Using command "gpio", user
>>> can retrieve this information as shown below:
>>>
>>> STM32MP> gpio state -a
>>>
>>> Bank GPIOA:
>>> GPIOA0: unused: 0 [ ]
>>> GPIOA1: unused: 0 [ ]
>>> GPIOA2: unused: 0 [ ]
>>> GPIOA3: unused: 0 [ ]
>>> GPIOA4: unused: 0 [ ]
>>> GPIOA5: unused: 0 [ ]
>>> GPIOA6: unused: 0 [ ]
>>> GPIOA7: unused: 0 [ ]
>>> GPIOA8: func: 9
>>> GPIOA9: func: 10
>>> GPIOA10: unused: 0 [ ]
>>> GPIOA11: unused: 0 [ ]
>>> GPIOA12: unused: 0 [ ]
>>> GPIOA13: output: 1 [x] red.gpios
>>> GPIOA14: output: 0 [x] green.gpios
>>> GPIOA15: unused: 0 [ ]
>>>
>>> It shows that pin 8 and 9 of bank A are configured respectively in
>>> alternate function 9 and 10.
>>
>> Can you list that functionality? Isn't it something what should be shown
>> with a name instead of number?
> 
> Listing this functionality is possible and printing name instead of
> number also, but for each pins, alternate function configuration is
> different and need to store all these informations into a table, which
> consumes a lot of memory.
> 
>> I expect that user has to go to any decode table to find out what 9 or
>> 10 means.
> 
> Yes, using the SoC's datasheet, user can find the corresponding
> alternate function description.

Can you give some examples of that functionality or link to datasheet
and page?

M