Re: [PATCH 04/11] drm/i915: Don't WARN on HDCP toggle if get_hw_state returns false

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>,
	Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	ramalingm.c@intel.com, Sean Paul <seanpaul@chromium.org>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH 04/11] drm/i915: Don't WARN on HDCP toggle if get_hw_state returns false
Date: Mon, 9 Dec 2019 19:22:25 +0200	[thread overview]
Message-ID: <20191209172225.GW1208@intel.com> (raw)
In-Reply-To: <CAMavQKLROAneH7P+jXUUtdcSSvGjYyz_SE-zeFzYzoZokZFBrQ@mail.gmail.com>

On Mon, Dec 09, 2019 at 11:16:27AM -0500, Sean Paul wrote:
> On Mon, Dec 9, 2019 at 10:21 AM Ville Syrjälä
> <ville.syrjala@linux.intel.com> wrote:
> >
> > On Fri, Dec 06, 2019 at 08:52:33AM -0500, Sean Paul wrote:
> > > On Thu, Dec 05, 2019 at 09:39:35PM +0200, Ville Syrjälä wrote:
> > > > On Tue, Dec 03, 2019 at 12:36:27PM -0500, Sean Paul wrote:
> > > > > From: Sean Paul <seanpaul@chromium.org>
> > > > >
> > > > > Now that we can rely on transcoder disable to toggle signalling off,
> > > > > it's less of a catastrophe if get_hw_state() returns false.
> > > > >
> > > > > Once we enable MST, this will be a valid exit path and we want to make
> > > > > sure we're not spamming the logs needlessly.
> > > > >
> > > > > Signed-off-by: Sean Paul <seanpaul@chromium.org>
> > > > > ---
> > > > >  drivers/gpu/drm/i915/display/intel_ddi.c | 2 +-
> > > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > > index e8ac98a8ee7f..ca28913a4c9f 100644
> > > > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > > @@ -1983,7 +1983,7 @@ int intel_ddi_toggle_hdcp_signalling(struct intel_encoder *intel_encoder,
> > > > >   if (WARN_ON(!wakeref))
> > > > >           return -ENXIO;
> > > > >
> > > > > - if (WARN_ON(!intel_encoder->get_hw_state(intel_encoder, &pipe))) {
> > > > > + if (!intel_encoder->get_hw_state(intel_encoder, &pipe)) {
> > > >
> > > > How can this get called when the encoder is not enabled?
> > > > Feels like this whole thing is trying to paper over some
> > > > bigger bug in the hdcp code.
> > >
> > > In the MST patch, I've added a call to intel_hdcp_disable() in the connector
> > > destroy path. Usually toggling will be disabled as part of the check_link call
> > > that is initiated on unplug, so in the destroy path it's non-essential to do
> > > this again.
> >
> > Can't we just leave things be until userspace disables the thing?
> 
> The connector disappears, so userspace won't be able to disable it.

That would make everything broken. The connector should hang around
as a zombie until the last user disappears.

> 
> > If not, then we should know whether hdcp is still enabled. And if
> > hdcp is enabled so is the encoder, thus we don't need such silly
> > checks.
> 
> Alright, I'll look at taking this angle.
> 
> Sean
> 
> >
> > --
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel
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