Re: [Intel-gfx] [v3 6/8] drm/i915/display: Implement infoframes readback for LSPCON

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Jun 22, 2020 at 11:44:58AM +0000, Shankar, Uma wrote:
> 
> > > > > -----Original Message-----
> > > > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > Sent: Thursday, June 11, 2020 9:31 PM
> > > > > To: Shankar, Uma <uma.shankar@intel.com>
> > > > > Cc: intel-gfx@lists.freedesktop.org; jani.nikula@linux.intel.com;
> > > > > Mun, Gwan- gyeong <gwan-gyeong.mun@intel.com>
> > > > > Subject: Re: [v3 6/8] drm/i915/display: Implement infoframes
> > > > > readback for LSPCON
> > > > >
> > > > > On Thu, Jun 11, 2020 at 06:46:50PM +0300, Ville Syrjälä wrote:
> > > > > > On Thu, Jun 11, 2020 at 12:42:30AM +0530, Uma Shankar wrote:
> > > > > > > Implemented Infoframes enabled readback for LSPCON devices.
> > > > > > > This will help align the implementation with state readback
> > > > > > > infrastructure.
> > > > > > >
> > > > > > > Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/i915/display/intel_lspcon.c | 63
> > > > > > > ++++++++++++++++++++-
> > > > > > >  1 file changed, 61 insertions(+), 2 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/i915/display/intel_lspcon.c
> > > > > > > b/drivers/gpu/drm/i915/display/intel_lspcon.c
> > > > > > > index 9034ce6f20b9..0ebe9a700291 100644
> > > > > > > --- a/drivers/gpu/drm/i915/display/intel_lspcon.c
> > > > > > > +++ b/drivers/gpu/drm/i915/display/intel_lspcon.c
> > > > > > > @@ -576,11 +576,70 @@ void lspcon_set_infoframes(struct
> > > > > > > intel_encoder
> > > > > *encoder,
> > > > > > >  				  buf, ret);
> > > > > > >  }
> > > > > > >
> > > > > > > +static bool _lspcon_read_avi_infoframe_enabled_mca(struct
> > > > > > > +drm_dp_aux *aux) {
> > > > > > > +	int ret;
> > > > > > > +	u32 val = 0;
> > > > > > > +	u16 reg = LSPCON_MCA_AVI_IF_CTRL;
> > > > > > > +
> > > > > > > +	ret = drm_dp_dpcd_read(aux, reg, &val, 1);
> > > > > > > +	if (ret < 0) {
> > > > > > > +		DRM_ERROR("DPCD read failed, address 0x%x\n", reg);
> > > > > > > +		return false;
> > > > > > > +	}
> > > > > > > +
> > > > > > > +	if (val & LSPCON_MCA_AVI_IF_KICKOFF)
> > > > > > > +		return true;
> > > > > > > +
> > > > > > > +	return false;
> > > > > >
> > > > > > return val & ...;
> > > > > >
> > > > > > > +}
> > > > > > > +
> > > > > > > +static bool _lspcon_read_avi_infoframe_enabled_parade(struct
> > > > > > > +drm_dp_aux *aux) {
> > > > > > > +	int ret;
> > > > > > > +	u32 val = 0;
> > > > > > > +	u16 reg = LSPCON_PARADE_AVI_IF_CTRL;
> > > > > > > +
> > > > > > > +	ret = drm_dp_dpcd_read(aux, reg, &val, 1);
> > > > > > > +	if (ret < 0) {
> > > > > > > +		DRM_ERROR("DPCD read failed, address 0x%x\n", reg);
> > > > > > > +		return false;
> > > > > > > +	}
> > > > > > > +
> > > > > > > +	if (val & LSPCON_PARADE_AVI_IF_KICKOFF)
> > > > > > > +		return true;
> > > > > > > +
> > > > > > > +	return false;
> > > > > > > +}
> > > > > > > +
> > > > > > >  u32 lspcon_infoframes_enabled(struct intel_encoder *encoder,
> > > > > > >  			      const struct intel_crtc_state *pipe_config)  {
> > > > > > > -	/* FIXME actually read this from the hw */
> > > > > > > -	return 0;
> > > > > > > +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > > > > > +	struct intel_lspcon *lspcon = enc_to_intel_lspcon(encoder);
> > > > > > > +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > > > > > > +	bool infoframes_enabled;
> > > > > > > +	u32 mask = 0;
> > > > > > > +	u32 val;
> > > > > > > +
> > > > > > > +	if (lspcon->vendor == LSPCON_VENDOR_MCA)
> > > > > > > +		infoframes_enabled =
> > > > > _lspcon_read_avi_infoframe_enabled_mca(&intel_dp->aux);
> > > > > > > +	else
> > > > > > > +		infoframes_enabled =
> > > > > > > +_lspcon_read_avi_infoframe_enabled_parade(&intel_dp->aux);
> > > > > > > +
> > > > > > > +	if (infoframes_enabled)
> > > > > > > +		return true;
> > > > > >
> > > > > > This is supposed to return a bitmask of all enabled infoframes.
> > > >
> > > > > Actually since we're dealing with both the LSPCON specific stuff
> > > > > and DIP stuff for the DRM infoframe I think we should stop using
> > > > > using intel_hdmi_infoframes_enabled(), and instead provide a
> > > > > LSPCON specific replacement for it. That way we can directly
> > > > > return the abstract bitmask instead of pretending to return a bitmask of
> > the DIP bits.
> 
> We have DP (VSC etc) packets also managed as HDMI infoframes only. We can keep the
> same with bitmask as VIDEO_DIP_ENABLE_AVI_HSW for AVI and similarly VIDEO_DIP_ENABLE_GMP_HSW
> for DRM (HDR metadata). This will help all the helper align appropriately even in the intel_dump_pipe_config.

intel_dump_infoframe() does not use any platform specific bitmasks.
So I don't understand what you're talking about here.

> 
> Will fix this accordingly and send the next version. Hope this is ok.
> 
> > > > Sure,  will fix this and resend the next version.
> > > >
> > > > > >
> > > > > > Also my question "how do we turn off infoframes once enabled?"
> > > > > > from
> > > > > > https://patchwork.freedesktop.org/patch/351719/?series=72928&rev
> > > > > > =1
> > > > > > still remains unanswered...
> > > >
> > > > For the AVI infoframe we generally compute and change the respective
> > > > values. If no change is requested and computed we can let the
> > > > existing infoframes be transmitted. AFAIK there is no mechanism
> > > > called out, to explicitly disable this on Lspcon. Have not seen any
> > > > issues due to this, so
> > > hoping that it may be safe even if they are enabled.
> > >
> > > It's not valid to transmit infoframes to DVI sinks.
> > 
> > With your fix, we won't be enabling or setting the infoframe on DVI sinks.
> > If I understand correctly, we may have issue if we connect HDMI (where we
> > would have sent the infoframe) and later unplug and plug a DVI sink. With
> > unplug if Lspcon is not resetting this internally then this will be a problem. I will
> > try to get this information on Lspcon behavior.
> 
> Hi Ville,
> Searched various docs on LSPCON and couldn't find any mention of disabling infoframe.
> Reached out to few folks who were interfacing with Lspcon vendors and got this finally
> clarified.  The expectation is that LSPCON will reset stuff on unplug and will not send infoframes to DVI sink,
> so from source side we don't need to explicitly disable them. Lspcon will take care of this, this was
> tested for compliance as well by them.

Unplug is irrelevant. We also have the property by which the user can
force the inforframes off.

> 
> I will share the updated series adding your patch stopping infoframes to be sent to DVI sinks.
> Please review the same.
> 
> Thank & Regards,
> Uma Shankar
>  
> > > >
> > > > I am planning to take your patch from the series and float along
> > > > with this series, adding check for DRM Infoframes also. Hope that is ok ?
> > > >
> > > > Thanks Ville for your feedback.
> > > >
> > > > Regards,
> > > > Uma Shankar
> > > >
> > > > > > > +
> > > > > > > +	if (lspcon->hdr_supported) {
> > > > > > > +		val = intel_de_read(dev_priv,
> > > > > > > +				    HSW_TVIDEO_DIP_CTL(pipe_config-
> > > > > >cpu_transcoder));
> > > > > > > +		mask |= VIDEO_DIP_ENABLE_GMP_HSW;
> > > > > > > +
> > > > > > > +		if (val & mask)
> > > > > > > +			return val & mask;
> > > > > > > +	}
> > > > > > > +
> > > > > > > +	return false;
> > > > > > >  }
> > > > > > >
> > > > > > >  void lspcon_resume(struct intel_lspcon *lspcon)
> > > > > > > --
> > > > > > > 2.22.0
> > > > > >
> > > > > > --
> > > > > > Ville Syrjälä
> > > > > > Intel
> > > > >
> > > > > --
> > > > > Ville Syrjälä
> > > > > Intel
> > >
> > > --
> > > Ville Syrjälä
> > > Intel

-- 
Ville Syrjälä
Intel
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