[PATCH v3 7/7] drm/vc4: kms: Don't disable the muxing of an active CRTC

[Maxime Ripard]

On Thu, Nov 19, 2020 at 10:12:43AM +0100, Thomas Zimmermann wrote:
> Hi
> 
> Am 05.11.20 um 14:56 schrieb Maxime Ripard:
> > The current HVS muxing code will consider the CRTCs in a given state to
> > setup their muxing in the HVS, and disable the other CRTCs muxes.
> > 
> > However, it's valid to only update a single CRTC with a state, and in this
> > situation we would mux out a CRTC that was enabled but left untouched by
> > the new state.
> > 
> > Fix this by setting a flag on the CRTC state when the muxing has been
> > changed, and only change the muxing configuration when that flag is there.
> > 
> > Fixes: 87ebcd42fb7b ("drm/vc4: crtc: Assign output to channel automatically")
> > Reviewed-by: Hoegeun Kwon <hoegeun.kwon at samsung.com>
> > Tested-by: Hoegeun Kwon <hoegeun.kwon at samsung.com>
> > Signed-off-by: Maxime Ripard <maxime at cerno.tech>
> > ---
> >   drivers/gpu/drm/vc4/vc4_drv.h |  1 +
> >   drivers/gpu/drm/vc4/vc4_kms.c | 82 ++++++++++++++++++++---------------
> >   2 files changed, 48 insertions(+), 35 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
> > index 014113823647..325b53ff11b3 100644
> > --- a/drivers/gpu/drm/vc4/vc4_drv.h
> > +++ b/drivers/gpu/drm/vc4/vc4_drv.h
> > @@ -524,6 +524,7 @@ struct vc4_crtc_state {
> >   	struct drm_mm_node mm;
> >   	bool feed_txp;
> >   	bool txp_armed;
> > +	bool needs_muxing;
> 
> Maybe rather 'update_muxing'.
> 
> More generally, I'd separate fields that contain actual CRTC state, such
> assigned_channel, from those that only contain transitional state during
> update-commit, such as needs_muxing.

How would you separate them?

I'll use your other suggestions, thanks!
Maxime
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