Re: [PATCH 05/12] drm/i915: Track active streams also for DP SST

Jim Bride
2016-07-29T18:37:26Z

On Fri, Jul 29, 2016 at 02:36:23PM +0300, Ville Syrjälä wrote:
> On Fri, Jul 29, 2016 at 11:22:32AM +0200, Daniel Vetter wrote:
> > On Thu, Jul 28, 2016 at 05:50:41PM +0300, ville.syrjala@linux.intel.com wrote:
> > > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > >
> > > s/active_mst_links/active_streams/ and use it also for SST. We can then
> > > use this information in the hpd handling to see if the link is active
> > > or not, and thus whether we may need to retrain.
> > >
> > > Cc: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
> > > Cc: Jim Bride <jim.bride@linux.intel.com>
> > > Cc: Manasi D Navare <manasi.d.navare@intel.com>
> > > Cc: Durgadoss R <durgadoss.r@intel.com>
> > > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > Hm, more state not in the state structures, and not cross-checked :( Ben
> > Skeggs just pinged me on this, and one of the ideas he's now looking into
> > is a separate state array for mst ports to fully keep track of this. Kinda
> > like we keep track of the shared dplls.
>
> Yeah it's a bit a mess. The other option I've outlined before might be a
> fake crtc to drive the primary, and then use atomic enable/disable it at
> the right time depending the state the of the actual MST streams.
>
> Speaking of atomic/mst, I'm not sure our link retraining is really good
> enough for MST. IIRC I saw a note in the spec that the payloads and
> whatnot might get deallocated by the sink/hub if the link drops. I think
> I have to re-read the spec a few times to make sure, but if that's the
> case then we'd have to pimp up the link retraining to be MST aware. But,
> I had an alternative idea recently; What if we just force a modeset on
> all the pipes on that port? IIRC the spec even says that for link
> retraining we should really be doing more or less the full modeset
> sequence. It should also get rid of the FIFO underruns we now get every
> time we retrain the link. Any thoughts?

If we ensure that we train the link at the widest and fastest configuration
possible in the first place (which is how I interpret what the DP spec says
to do for link training) then we shouldn't be in a situation where we need
to retrain the main link unless the link is lost, in which case all of the
pipes & payloads associated with the link will need to be re-configured
anyhow (since there's no guarantee that the link bandwidth will be the same
once the re-training was done.) This seems like a simpler solution, IMHO.

Jim

> >
> > Again just ideas, code looks correct.
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >
> > > ---
> > > drivers/gpu/drm/i915/intel_ddi.c | 10 ++++++++++
> > > drivers/gpu/drm/i915/intel_dp.c | 8 +++++++-
> > > drivers/gpu/drm/i915/intel_dp_mst.c | 16 ++++++++--------
> > > drivers/gpu/drm/i915/intel_drv.h | 2 +-
> > > 4 files changed, 26 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > > index 3b3a0a808477..bc188ee6e37f 100644
> > > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > > @@ -1616,6 +1616,9 @@ static void intel_ddi_pre_enable(struct intel_encoder *intel_encoder)
> > >
> > > intel_ddi_init_dp_buf_reg(intel_encoder);
> > >
> > > + WARN_ON(intel_dp->active_streams != 0);
> > > + intel_dp->active_streams++;
> > > +
> > > intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > > intel_dp_start_link_train(intel_dp);
> > > if (port != PORT_A || INTEL_INFO(dev_priv)->gen >= 9)
> > > @@ -1733,6 +1736,13 @@ static void intel_disable_ddi(struct intel_encoder *intel_encoder)
> > > intel_psr_disable(intel_dp);
> > > intel_edp_backlight_off(intel_dp);
> > > }
> > > +
> > > + if (type == INTEL_OUTPUT_DP || type == INTEL_OUTPUT_EDP) {
> > > + struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > +
> > > + intel_dp->active_streams--;
> > > + WARN_ON(intel_dp->active_streams != 0);
> > > + }
> > > }
> > >
> > > bool bxt_ddi_phy_is_enabled(struct drm_i915_private *dev_priv,
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > > index 0096c651c21f..3a9c5d3b5c66 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -2685,6 +2685,9 @@ static void intel_enable_dp(struct intel_encoder *encoder)
> > > lane_mask);
> > > }
> > >
> > > + WARN_ON(intel_dp->active_streams != 0);
> > > + intel_dp->active_streams++;
> > > +
> > > intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_ON);
> > > intel_dp_start_link_train(intel_dp);
> > > intel_dp_stop_link_train(intel_dp);
> > > @@ -3344,6 +3347,9 @@ intel_dp_link_down(struct intel_dp *intel_dp)
> > >
> > > DRM_DEBUG_KMS("\n");
> > >
> > > + intel_dp->active_streams--;
> > > + WARN_ON(intel_dp->active_streams != 0);
> > > +
> > > if ((IS_GEN7(dev) && port == PORT_A) ||
> > > (HAS_PCH_CPT(dev) && port != PORT_A)) {
> > > DP &= ~DP_LINK_TRAIN_MASK_CPT;
> > > @@ -3826,7 +3832,7 @@ go_again:
> > > if (bret == true) {
> > >
> > > /* check link status - esi[10] = 0x200c */
> > > - if (intel_dp->active_mst_links &&
> > > + if (intel_dp->active_streams &&
> > > !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
> > > DRM_DEBUG_KMS("channel EQ not ok, retraining\n");
> > > intel_dp_start_link_train(intel_dp);
> > > diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > index 68a005d729e9..857cfa6928b3 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp_mst.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp_mst.c
> > > @@ -99,7 +99,7 @@ static void intel_mst_disable_dp(struct intel_encoder *encoder)
> > > struct intel_dp *intel_dp = &intel_dig_port->dp;
> > > int ret;
> > >
> > > - DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > > + DRM_DEBUG_KMS("%d\n", intel_dp->active_streams);
> > >
> > > drm_dp_mst_reset_vcpi_slots(&intel_dp->mst_mgr, intel_mst->connector->port);
> > >
> > > @@ -115,7 +115,7 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder)
> > > struct intel_digital_port *intel_dig_port = intel_mst->primary;
> > > struct intel_dp *intel_dp = &intel_dig_port->dp;
> > >
> > > - DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > > + DRM_DEBUG_KMS("%d\n", intel_dp->active_streams);
> > >
> > > /* this can fail */
> > > drm_dp_check_act_status(&intel_dp->mst_mgr);
> > > @@ -124,10 +124,10 @@ static void intel_mst_post_disable_dp(struct intel_encoder *encoder)
> > >
> > > drm_dp_mst_deallocate_vcpi(&intel_dp->mst_mgr, intel_mst->connector->port);
> > >
> > > - intel_dp->active_mst_links--;
> > > + intel_dp->active_streams--;
> > >
> > > intel_mst->connector = NULL;
> > > - if (intel_dp->active_mst_links == 0) {
> > > + if (intel_dp->active_streams == 0) {
> > > intel_dig_port->base.post_disable(&intel_dig_port->base);
> > > intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
> > > }
> > > @@ -165,11 +165,11 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder)
> > > */
> > > found->encoder = encoder;
> > >
> > > - DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > > + DRM_DEBUG_KMS("%d\n", intel_dp->active_streams);
> > >
> > > intel_mst->connector = found;
> > >
> > > - if (intel_dp->active_mst_links == 0) {
> > > + if (intel_dp->active_streams == 0) {
> > > intel_prepare_ddi_buffer(&intel_dig_port->base);
> > >
> > > intel_ddi_clk_select(&intel_dig_port->base, intel_crtc->config);
> > > @@ -193,7 +193,7 @@ static void intel_mst_pre_enable_dp(struct intel_encoder *encoder)
> > > }
> > >
> > >
> > > - intel_dp->active_mst_links++;
> > > + intel_dp->active_streams++;
> > > temp = I915_READ(DP_TP_STATUS(port));
> > > I915_WRITE(DP_TP_STATUS(port), temp);
> > >
> > > @@ -210,7 +210,7 @@ static void intel_mst_enable_dp(struct intel_encoder *encoder)
> > > enum port port = intel_dig_port->port;
> > > int ret;
> > >
> > > - DRM_DEBUG_KMS("%d\n", intel_dp->active_mst_links);
> > > + DRM_DEBUG_KMS("%d\n", intel_dp->active_streams);
> > >
> > > if (intel_wait_for_register(dev_priv,
> > > DP_TP_STATUS(port),
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index 70d7f33d6747..7fef18288aa2 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -894,7 +894,7 @@ struct intel_dp {
> > >
> > > bool can_mst; /* this port supports mst */
> > > bool is_mst;
> > > - int active_mst_links;
> > > + int active_streams; /* number of active streams (for SST and MST both) */
> > > /* connector directly attached - won't be use for modeset in mst world */
> > > struct intel_connector *attached_connector;
> > >
> > > --
> > > 2.7.4
> > >
> > > _______________________________________________
> > > Intel-gfx mailing list
> > > Intel-gfx@lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
>
> --
> Ville Syrjälä
> Intel OTC
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