[Intel-gfx] [PATCH 06/11] drm/i915: Update intel_dp_hpd_pulse() to check link status for non-MST operation

[Paulo Zanoni]

2015-04-01 15:00 GMT-03:00 Todd Previte <tprevite at gmail.com>:
> Update the hot plug function to handle the SST case. Instead of placing
> the SST case within the long/short pulse block, it is now handled after
> determining that MST mode is not in use. This way, the topology management
> layer can handle any MST-related operations while SST operations are still
> correctly handled afterwards.
>
> This patch also corrects the problem of SST mode only being handled in the
> case of a short (0.5ms - 1.0ms) HPD pulse.

It's not clear to me what exactly is the problem with the current
code. Can you please clarify?


> For compliance testing purposes
> both short and long pulses are used by the different tests, thus both cases
> need to be addressed for SST.
>
> This patch replaces [PATCH 10/10] drm/i915: Fix intel_dp_hot_plug() in the
> previous compliance testing patch sequence. Review feedback on that patch
> indicated that updating intel_dp_hot_plug() was not the correct place for
> the test handler.
>
> For the SST case, the main stream is disabled for long HPD pulses as this
> generally indicates either a connect/disconnect event or link failure. For
> a number of case in compliance testing, the source is required to disable
> the main link upon detection of a long HPD.
>
> V2:
> - N/A
> V3:
> - Place the SST mode link status check into the mst_fail case
> - Remove obsolete comment regarding SST mode operation
> - Removed an erroneous line of code that snuck in during rebasing
> V4:
> - Added a disable of the main stream (DP transport) for the long pulse case
>   for SST to support compliance testing
> V5:
> - Reworked SST handling to support tests 4.2.2.7 and 4.2.2.8
>
> Signed-off-by: Todd Previte <tprevite at gmail.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 28 +++++++++++-----------------
>  1 file changed, 11 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 16d35903..0a77f5a 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4622,16 +4622,6 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>                         if (intel_dp_check_mst_status(intel_dp) == -EINVAL)
>                                 goto mst_fail;
>                 }
> -
> -               if (!intel_dp->is_mst) {
> -                       /*
> -                        * we'll check the link status via the normal hot plug path later -
> -                        * but for short hpds we should check it now
> -                        */
> -                       drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
> -                       intel_dp_check_link_status(intel_dp);
> -                       drm_modeset_unlock(&dev->mode_config.connection_mutex);
> -               }
>         }
>
>         ret = IRQ_HANDLED;
> @@ -4639,18 +4629,22 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>         goto put_power;
>  mst_fail:
>         /* if we were in MST mode, and device is not there get out of MST mode */
> -       if (intel_dp->is_mst) {
> -               DRM_DEBUG_KMS("MST device may have disappeared %d vs %d\n", intel_dp->is_mst, intel_dp->mst_mgr.mst_state);
> -               intel_dp->is_mst = false;
> -               drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> -       } else {
> -               /* SST mode - handle short/long pulses here */
> +       DRM_DEBUG_KMS("MST device may have disappeared %d vs %d\n", intel_dp->is_mst, intel_dp->mst_mgr.mst_state);

So now aren't we going to get MST log messages on non-MST cases, such
as a disconnect with long_hpd? I mean, even non-MST jumps to the
mst_fail label.


> +       intel_dp->is_mst = false;
> +       drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> +
> +put_power:
> +       /* SST mode - handle short/long pulses here */
> +       if (!intel_dp->is_mst) {
> +               /* TO DO: Handle short/long pulses individually
> +                       Can save on training times and overhead by not doing
> +                       full link status updating/processing for short pulses
> +                */
>                 drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>                 intel_dp_check_link_status(intel_dp);
>                 drm_modeset_unlock(&dev->mode_config.connection_mutex);
>                 ret = IRQ_HANDLED;
>         }
> -put_power:
>         intel_display_power_put(dev_priv, power_domain);
>
>         return ret;
> --
> 1.9.1
>
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-- 
Paulo Zanoni