[Intel-gfx] [PATCH] drm/i915/vlv: DP_SINK_COUNT is not reliable for valleyview platform.

[Wang, Quanxian]

> -----Original Message-----
> From: Daniel Vetter [mailto:daniel.vetter at ffwll.ch] On Behalf Of Daniel
> Vetter
> Sent: Friday, June 13, 2014 3:16 PM
> To: Wang, Quanxian
> Cc: intel-gfx at lists.freedesktop.org
> Subject: Re: [Intel-gfx] [PATCH] drm/i915/vlv: DP_SINK_COUNT is not
> reliable for valleyview platform.
> 
> On Fri, Jun 13, 2014 at 02:52:04PM +0800, Quanxian Wang wrote:
> > DP connector will be disconnected after chvt to another console for 10
> > minutes or more on valleyview platform VTC1010.
> 
> This needs _much_ more detail, really.
[Wang, Quanxian] Sorry, I am not sure what detail should be provided.
The background is  in tizen-ivi, when Weston is running on vt1, and chvt to vt2, after 10 or more minutes, Weston will exit.
After the investigation, I found in intel_dp_detect_dpcd function, it will use DP_SINK_COUNT to check if connector is connected or not.  KMS think it is not connected and return connector_status_disconnected, this will disable the DP connector. Weston will not get any disconnector, it will exit. That is the root cause. So I think use DP_SINK_COUNT is not reliable to check connector is connected or not.
> 
> Also it smells like we work around a sink issue, which means the correct quirk
> is to use some sink id (like OUI), _not_ the platform. Since this way you break
> all DP1.1+ stuff on vlv and if someone puts this panel onto a different
> platform it still doesn't work.
[Wang, Quanxian] Yes, it is a special issue happens on valleyview platform VTC1010. I just have only one type of valleyview platform vtc1010 and not sure if others vlv platform has the same issue which has dp1.1.
> 
> Or I completely don't understand this at all.
> 
> Also, such a patch needs a full spec quote or a w/a citation or something solid
> if it's a more generic issue.
[Wang, Quanxian] I am checking the related registers. Thanks.
> -Daniel
> >
> > Signed-off-by: Quanxian Wang <quanxian.wang at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c index 2688f6d..0d127a5 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -2942,6 +2942,7 @@ intel_dp_check_link_status(struct intel_dp
> > *intel_dp)  static enum drm_connector_status
> > intel_dp_detect_dpcd(struct intel_dp *intel_dp)  {
> > +	struct drm_device *dev = intel_dp_to_dev(intel_dp);
> >  	uint8_t *dpcd = intel_dp->dpcd;
> >  	uint8_t type;
> >
> > @@ -2953,7 +2954,8 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
> >  		return connector_status_connected;
> >
> >  	/* If we're HPD-aware, SINK_COUNT changes dynamically */
> > -	if (intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> > +	if (!IS_VALLEYVIEW(dev) &&
> > +	    intel_dp->dpcd[DP_DPCD_REV] >= 0x11 &&
> >  	    intel_dp->downstream_ports[0] & DP_DS_PORT_HPD) {
> >  		uint8_t reg;
> >  		if (!intel_dp_aux_native_read_retry(intel_dp,
> DP_SINK_COUNT,
> > --
> > 1.8.1.2
> >
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> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch