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

[Dmitry Baryshkov]

On Tue, Mar 11, 2025 at 09:07:10AM +0100, Maxime Ripard wrote:
> 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 at 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 at 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?

I'd really prefer to follow the drm_connector.infoframes.audio. It makes
sense to group all ALSA-related functionality together. Maybe I should
refactor it to:

struct drm_connector {
    struct {
	struct mutex lock;
	struct drm_connector_hdmi_infoframe audio_infoframe;
	unsigned long long tmds_char_rate;
    } audio;
};

WDYT? If that doesn't sound appealing, I'll go the connetion_mutex and
drm_connector_state way.

-- 
With best wishes
Dmitry