[U-Boot] [Uboot-stm32] [PATCH v3 0/5] Add get_alt_function ops

[Patrice CHOTARD]

On 09/11/2018 02:17 PM, Michal Simek wrote:
> 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?

As example, regarding the pin 8 of bank A (GPIOA8 above), alternate
function 9 means that pins is currently configured as SDMMC2_DATA4.

For this pins, here are all the possible alternate function :
	
alternate function 	description

AF0 			MCO0
AF1			TIM1_CH1
AF2
AF3			TIM8_BKIN2
AF4			I2C3_SCL
AF5			SPI3_MOSI/SDO
AF6
AF7			USART1_CK
AF8			SDMMC2 CKIN
AF9 			SDMMC2 DATA4
AF10			USB_SOF
AF11
AF12			SAI4_SD_B
AF13			UART7_RX
AF14 			LCD_R6
AF15 			EVENTOUT

Patrice

> 
> M
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