[PATCH] i2c: correct I2C deblock logic

[Heiko Schocher]

Hi!

On 13.03.23 03:55, Bough Chen wrote:
>> -----Original Message-----
>> From: Bough Chen <haibo.chen at nxp.com>
>> Sent: 2023年2月10日 17:27
>> To: hs at denx.de; al.kochet at gmail.com; marex at denx.de
>> Cc: u-boot at lists.denx.de; dl-uboot-imx <uboot-imx at nxp.com>;
>> xypron.glpk at gmx.de; Bough Chen <haibo.chen at nxp.com>
>> Subject: [PATCH] i2c: correct I2C deblock logic
>>
>> From: Haibo Chen <haibo.chen at nxp.com>
>>
>> Current code use dm_gpio_get_value() to get SDA and SCL value, and the value
>> depends on the flag GPIOD_ACTIVE_LOW. When toggle SCL to wait slave
>> release SDA, the SDA are config as GPIOD_IS_IN, and whether contain the
>> GPIOD_ACTIVE_LOW depends on the DTS setting. Usually, for I2C GPIO, we use
>> GPIOD_ACTIVE_LOW flag in DTS, so if the SDA is in low level, then
>> dm_gpio_get_value() will return 1, current code logic will stop the SCL toggle
>> wrongly, cause the I2C deblock not work as expect.
>>
>> This patch force set the GPIOD_ACTIVE_LOW for both GPIOD_IS_IN and
>> GPIOD_IS_OUT, and make the return value of i2c_gpio_get_pin() eaqual to the
>> physical voltage logic level.
>>
> 
> Hi, 
> 
> Any comments for this patch, just a reminder in case you miss it.

Indeed, I missed this patch, sorry!
Your explanation sounds reasonable to me, but I wonder if nobody tapped
into this problem... it would be good to have some test reports
from others! Also added Simon, as he did a lot of work in this space.

Thanks!

bye,
Heiko
> 
> Best Regards
> Haibo Chen
>  
>> Fixes: aa54192d4a87 ("dm: i2c: implement gpio-based I2C deblock")
>> Signed-off-by: Haibo Chen <haibo.chen at nxp.com>
>> ---
>>  drivers/i2c/i2c-uclass.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c index
>> 8d9a89ed89..4dc707c659 100644
>> --- a/drivers/i2c/i2c-uclass.c
>> +++ b/drivers/i2c/i2c-uclass.c
>> @@ -505,7 +505,8 @@ uint i2c_get_chip_addr_offset_mask(struct udevice
>> *dev)  static void i2c_gpio_set_pin(struct gpio_desc *pin, int bit)  {
>>  	if (bit)
>> -		dm_gpio_set_dir_flags(pin, GPIOD_IS_IN);
>> +		dm_gpio_set_dir_flags(pin, GPIOD_IS_IN |
>> +					   GPIOD_ACTIVE_LOW);
>>  	else
>>  		dm_gpio_set_dir_flags(pin, GPIOD_IS_OUT |
>>  					   GPIOD_ACTIVE_LOW |
>> @@ -514,7 +515,7 @@ static void i2c_gpio_set_pin(struct gpio_desc *pin, int
>> bit)
>>
>>  static int i2c_gpio_get_pin(struct gpio_desc *pin)  {
>> -	return dm_gpio_get_value(pin);
>> +	return !dm_gpio_get_value(pin);
>>  }
>>
>>  int i2c_deblock_gpio_loop(struct gpio_desc *sda_pin,
>> --
>> 2.34.1
> 

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