Re: [PATCH 3/4] drm/vc4: use new helper to get ACR values

[Maxime Ripard <mripard@kernel.org>]

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On Mon, Mar 10, 2025 at 10:18:04PM +0200, Dmitry Baryshkov wrote:
> On Mon, Mar 10, 2025 at 03:51:53PM +0100, Maxime Ripard wrote:
> > On Sun, Mar 09, 2025 at 10:13:58AM +0200, Dmitry Baryshkov wrote:
> > > From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > > 
> > > Use drm_hdmi_acr_get_n_cts() helper instead of calculating N and CTS
> > > values in the VC4 driver.
> > > 
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > > ---
> > >  drivers/gpu/drm/vc4/vc4_hdmi.c | 10 +++-------
> > >  drivers/gpu/drm/vc4/vc4_hdmi.h |  7 +++++++
> > >  2 files changed, 10 insertions(+), 7 deletions(-)
> > > 
> 
> > > diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.h b/drivers/gpu/drm/vc4/vc4_hdmi.h
> > > index e3d989ca302b72533c374dfa3fd0d5bd7fe64a82..0a775dbfe99d45521f3d0a2016555aefa81d7934 100644
> > > --- a/drivers/gpu/drm/vc4/vc4_hdmi.h
> > > +++ b/drivers/gpu/drm/vc4/vc4_hdmi.h
> > > @@ -211,6 +211,13 @@ struct vc4_hdmi {
> > >  	 * KMS hooks. Protected by @mutex.
> > >  	 */
> > >  	enum hdmi_colorspace output_format;
> > > +
> > > +	/**
> > > +	 * @tmds_char_rate: Copy of
> > > +	 * @drm_connector_state.hdmi.tmds_char_rate for use outside of
> > > +	 * KMS hooks. Protected by @mutex.
> > > +	 */
> > > +	unsigned long long tmds_char_rate;
> > >  };
> > 
> > This should be in drm_connector_hdmi if it's useful
> 
> That would mean bringing the state to a non-state structure on the
> framework level. Is it fine from your POV?

Sorry, I'm changing my mind a little bit, but it's pretty much the same
case than for accessing the infoframes from debugfs: we want to get some
information stored in the state from outside of KMS.

What we did for the infoframes is that we're actually just taking the
connection_mutex from the DRM device and access the drm_connector->state
pointer.

I guess it would also work for ALSA?

Maxime

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