Re: [PATCH 4/4] drm: bridge: simple-bridge: add tdp158 support

[Marc Gonzalez <mgonzalez@freebox.fr>]

On 18/06/2024 00:33, Dmitry Baryshkov wrote:

> On Mon, Jun 17, 2024 at 06:03:02PM GMT, Marc Gonzalez wrote:
> 
>> +	if (sbridge->vcc) {
>> +		ret = regulator_enable(sbridge->vcc);
>> +		msleep(100);
> 
> At least this should be documented or explained in the commit message.
> Is it absolutely necessary? Can you use regulator-enable-ramp-delay or
> any other DT property instead?

The value comes from datasheet "8.3.2 Operation Timing"
Table 1. Power Up and Operation Timing Requirements
VDD supply ramp up requirements, max = 100 ms
VCC supply ramp up requirements, max = 100 ms

Did I read the spec wrong? (Very possible)

Are you saying this could/should be a property of the regulator?
What if the regulator gates several different blocks?


>>  	sbridge = devm_kzalloc(dev, sizeof(*sbridge), GFP_KERNEL);
>>  	if (!sbridge)
>>  		return -ENOMEM;
>> -	platform_set_drvdata(pdev, sbridge);
> 
> I think this call can get dropped together with the remove() being
> gone...

Oooh, it didn't occur to me that the only reason to store drvdata was
to have it available in the remove callback...


> Does this work if the driver is built as a module?

Not sure there's any point in testing since Maxime NACKed the approach.

Regards