[PATCHv2 02/22] drm/bridge: tc358767: reset voltage-swing & pre-emphasis

[Tomi Valkeinen]

On 20/04/2019 23:30, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Tue, Mar 26, 2019 at 12:31:26PM +0200, Tomi Valkeinen wrote:
>> We need to reset DPCD voltage-swing & pre-emphasis before starting the
>> link training, as otherwise tc358767 will use the previous values as
>> minimums.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen at ti.com>
>> ---
>>  drivers/gpu/drm/bridge/tc358767.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
>> index 7031c4f52c57..11a50f7bb4be 100644
>> --- a/drivers/gpu/drm/bridge/tc358767.c
>> +++ b/drivers/gpu/drm/bridge/tc358767.c
>> @@ -956,6 +956,12 @@ static int tc_main_link_setup(struct tc_data *tc)
>>  	if (ret < 0)
>>  		goto err_dpcd_write;
>>  
>> +	// Reset voltage-swing & pre-emphasis
> 
> The driver uses C-style comments, I think it would be best to stick to
> them to avoid a style mismatch.

Oops. Yep. I often use c++ comments when hacking/developing as they're
often easier to use. Sometimes I miss converting them to c comments...

> 
>> +	tmp[0] = tmp[1] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_0;
> 
> You may want to wrap the line.

Well, I personally don't think wrapping at 80 is a good idea. Something
like 120 is more sensible and makes the code more readable.

I can wrap it if you insist =)

>> +	ret = drm_dp_dpcd_write(aux, DP_TRAINING_LANE0_SET, tmp, 2);
> 
> What branch does this series apply to ? DP_TRAINING_LANE0_SET isn't
> defined in Linus' or Dave's master branches.

It's there. At least v5.0 has it.

>> +	if (ret < 0)
>> +		goto err_dpcd_write;
>> +
> 
> I can't comment on this as I don't have access to the device
> documentation :-(

Hmm, comment on what?

>>  	ret = tc_link_training(tc, DP_TRAINING_PATTERN_1);
>>  	if (ret)
>>  		goto err;
> 

 Tomi

-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki