Re: [PATCH RFC 03/10] drm/panel: Add LGD panel driver for Sony Xperia XZ3

[Dmitry Baryshkov]

On 30/05/2023 00:11, Marijn Suijten wrote:
> On 2023-05-22 04:16:20, Dmitry Baryshkov wrote:
> <snip>
> > > +	if (ctx->dsi->dsc) {
> >
> > dsi->dsc is always set, thus this condition can be dropped.
>
> I want to leave room for possibly running the panel without DSC (at a
> lower resolution/refresh rate, or at higher power consumption if there
> is enough BW) by not assigning the pointer, if we get access to panel
> documentation: probably one of the magic commands sent in this driver
> controls it but we don't know which.

This sounds like 'a possible room for expansion' which might never be 
actually used. I think, if we ever get such information or when the 
panel's DSC config gets variadic following the mode, we can reintroduce 
this check.

> > > +		drm_dsc_pps_payload_pack(&pps, ctx->dsi->dsc);
> > > +
> > > +		ret = mipi_dsi_picture_parameter_set(ctx->dsi, &pps);
> > > +		if (ret < 0) {
> > > +			dev_err(panel->dev, "failed to transmit PPS: %d\n", ret);
> > > +			goto fail;
> > > +		}
> > > +		ret = mipi_dsi_compression_mode(ctx->dsi, true);
> > > +		if (ret < 0) {
> > > +			dev_err(dev, "failed to enable compression mode: %d\n", ret);
> > > +			goto fail;
> > > +		}
> > > +
> > > +		msleep(28);
> > > +	}
> > > +
> > > +	ctx->prepared = true;
> > > +	return 0;
> > > +
> > > +fail:
> > > +	gpiod_set_value_cansleep(ctx->reset_gpio, 0);
> > > +	regulator_disable(ctx->vddio);
> > > +	return ret;
> > > +}
> <snip>
> > > +	/* This panel only supports DSC; unconditionally enable it */

--
With best wishes
Dmitry