RE: [PATCH v4 02/11] drm/bridge: it6505: fix aux operation for edid read

[<Hermes.Wu@ite.com.tw>]

>On Thu, Sep 26, 2024 at 03:47:52PM GMT, Hermes Wu wrote:
>> From: Hermes Wu <Hermes.wu@ite.com.tw>
>> 
>> The EDID read operation can reach the maximum size of the AUX FIFO buffer.
>
>And? Commit message should describe why the change is necessary and what is being done. Just providing a statement is not enough.
>

The original AUX operation treat all reads by using data registers will be limited at 4 bytes.
AUX operation command CMD_AUX_I2C_EDID_READ using AUX FIFO is capable of reads data by 16 bytes each time.
It can improve speed of read EDID.


>> 
>> Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
>> Signed-off-by: Hermes Wu <Hermes.wu@ite.com.tw>
>> ---
>>  drivers/gpu/drm/bridge/ite-it6505.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c 
>> b/drivers/gpu/drm/bridge/ite-it6505.c
>> index 28a8043229d3..b451d3c2ac1d 100644
>> --- a/drivers/gpu/drm/bridge/ite-it6505.c
>> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
>> @@ -1078,8 +1078,11 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
>>  	int i, ret_size, ret = 0, request_size;
>>  
>>  	mutex_lock(&it6505->aux_lock);
>> -	for (i = 0; i < size; i += 4) {
>> -		request_size = min((int)size - i, 4);
>> +	for (i = 0; i < size; ) {
>> +		if (cmd == CMD_AUX_I2C_EDID_READ)
>> +			request_size = min_t(int, (int)size - i, AUX_FIFO_MAX_SIZE);
>> +		else
>> +			request_size = min_t(int, (int)size - i, 4);
>>  		ret_size = it6505_aux_operation(it6505, cmd, address + i,
>>  						buffer + i, request_size,
>>  						reply);
>> @@ -1088,6 +1091,7 @@ static ssize_t it6505_aux_do_transfer(struct it6505 *it6505,
>>  			goto aux_op_err;
>>  		}
>>  
>> +		i += request_size;
>>  		ret += ret_size;
>>  	}
>>  
>> --
>> 2.34.1
>> 
>
>-- 
>With best wishes
>Dmitry
>

BR,
Hermes