[PATCH v4 10/10] drm/vs: add simple dsi encoder

[Dmitry Baryshkov]

On Sun, Jun 23, 2024 at 07:17:09AM GMT, Keith Zhao wrote:
> Hi Dmitry:
> 
> > On Tue, May 21, 2024 at 06:58:17PM +0800, keith wrote:

> > > +								  "starfive,syscon",
> > > +								  2, args);
> > > +
> > > +	if (IS_ERR(simple->dss_regmap)) {
> > > +		return dev_err_probe(dev, PTR_ERR(simple->dss_regmap),
> > > +				     "getting the regmap failed\n");
> > > +	}
> > > +
> > > +	simple->offset = args[0];
> > > +	simple->mask = args[1];
> > 
> > Is the value that you've read platform dependent or use case dependent?
> > What is the actual value being written? Why are you using syscon for it?
> 
> The syscon is used to select crtcs binded with encoder,
> If this encoder binds to crtc0 , set the syscon reg bit0 = 1
> If this encoder binds to crtc1 , set the syscon reg bit1 = 1 (0x2)
> Maybe I can do this by the possible_crtc instead of using args from dts

If this is a constant between your platforms, it should not be a part of
DT.

> 
> 
> > 
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static void vs_encoder_atomic_enable(struct drm_encoder *encoder,
> > > +struct drm_atomic_state *state) {
> > > +	struct vs_simple_encoder *simple = to_simple_encoder(encoder);
> > > +
> > > +	regmap_update_bits(simple->dss_regmap, simple->offset, simple->mask,
> > > +simple->mask);
> > 
> > 
> > A purist in me would ask to have separate mask and value to write.
> Understand , will avoid this action 
> > 
> > > +}
> > 
> > Is it necessary to clear those bits when stopping the stream?
> No need to do this , if clear those bits , the encoder will point to a unknown crtc

what are the consequences? Is it desirable or not?

-- 
With best wishes
Dmitry