On Tue, Jun 25, 2024 at 08:33:48AM GMT, Keith Zhao wrote:
>
>
> > -----Original Message-----
> > From: Dmitry Baryshkov <dmitry.barysh...@linaro.org>
> > Sent: 2024年6月24日 5:11
> > To: Keith Zhao <keith.z...@starfivetech.com>
> > Cc: andrzej.ha...@intel.com; neil.armstr...@linaro.org; rf...@kernel.org;
> > laurent.pinch...@ideasonboard.com; jo...@kwiboo.se;
> > jernej.skra...@gmail.com; maarten.lankho...@linux.intel.com;
> > mrip...@kernel.org; tzimmerm...@suse.de; airl...@gmail.com;
> > dan...@ffwll.ch; r...@kernel.org; krzk...@kernel.org; conor...@kernel.org;
> > h...@rock-chips.com; he...@sntech.de; andy....@rock-chips.com; Xingyu Wu
> > <xingyu...@starfivetech.com>; p.za...@pengutronix.de; Jack Zhu
> > <jack....@starfivetech.com>; Shengyang Chen
> > <shengyang.c...@starfivetech.com>; dri-devel@lists.freedesktop.org;
> > devicet...@vger.kernel.org; linux-ker...@vger.kernel.org;
> > linux-arm-ker...@lists.infradead.org
> > Subject: Re: [PATCH v4 10/10] drm/vs: add simple dsi encoder
> >
> > 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?
> There are two crtcs.
> Each display terminal encoder can combine any crtc, depending on the value of
> possible crtc.
> When the bit is 0, it means that the encoder matches crtc0.
> When the bit is 1, it means that the encoder matches crtc1.
> The possible crtc of this encoder is 2 , the reg bit is 1.
> When the video stream is stopped, if the bit is cleared, the result is that
> the encoder hardware points to crtc0,
> and the encoder points to crtc1 based on the drm framework(because the
> possible crtc no change).
I'm not sure if I understood you correctly. If it doesn't disable or
disconnect the encoder, I'd skip that in the .disable path.
--
With best wishes
Dmitry
