Re: [PATCH v2] drm/i915/dp: Clean up intel_dp_check_mst_status

Ausmus, James
2017-09-22T17:54:00Z

On Thu, Sep 21, 2017 at 11:54 AM, Dhinakaran Pandiyan
<dhinakaran.pandiyan@intel.com> wrote:
> Rewriting this code without the goto, I believe, makes it more readable.
> One functional change that has been included is the handling of failed ESI
> register reads. Instead of disabling MST only for the first failed read, we
> now disable MST on subsequent failed reads too. A failed ESI read is
> problematic irrespective of whether it is the first or not.
>
> v2: Don't ignore return from _mst_hpd_irq() (James)
>
> Cc: James Ausmus <james.ausmus@intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>

Reviewed-by: James Ausmus <james.ausmus@intel.com>

> ---
> drivers/gpu/drm/i915/intel_dp.c | 78 ++++++++++++++++++-----------------------
> 1 file changed, 34 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 98e7b96ca826..aa97bd825369 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -4191,57 +4191,47 @@ static void intel_dp_handle_test_request(struct intel_dp *intel_dp)
> static int
> intel_dp_check_mst_status(struct intel_dp *intel_dp)
> {
> - bool bret;
> + u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> + struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
>
> - if (intel_dp->is_mst) {
> - u8 esi[DP_DPRX_ESI_LEN] = { 0 };
> - int ret = 0;
> - int retry;
> + if (!intel_dp->is_mst)
> + return -EINVAL;
> +
> + while (intel_dp_get_sink_irq_esi(intel_dp, esi)) {
> + int ret, retry;
> bool handled;
> - bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> -go_again:
> - if (bret == true) {
> -
> - /* check link status - esi[10] = 0x200c */
> - if (intel_dp->active_mst_links &&
> - !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);
> - intel_dp_stop_link_train(intel_dp);
> - }
>
> - DRM_DEBUG_KMS("got esi %3ph\n", esi);
> - ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
> -
> - if (handled) {
> - for (retry = 0; retry < 3; retry++) {
> - int wret;
> - wret = drm_dp_dpcd_write(&intel_dp->aux,
> - DP_SINK_COUNT_ESI+1,
> - &esi[1], 3);
> - if (wret == 3) {
> - break;
> - }
> - }
> + DRM_DEBUG_KMS("ESI %3ph\n", esi);
>
> - bret = intel_dp_get_sink_irq_esi(intel_dp, esi);
> - if (bret == true) {
> - DRM_DEBUG_KMS("got esi2 %3ph\n", esi);
> - goto go_again;
> - }
> - } else
> - ret = 0;
> + /* check link status - esi[10] = 0x200c */
> + if (intel_dp->active_mst_links &&
> + !drm_dp_channel_eq_ok(&esi[10], intel_dp->lane_count)) {
> + intel_dp_start_link_train(intel_dp);
> + intel_dp_stop_link_train(intel_dp);
> + }
>
> - return ret;
> - } else {
> - struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> - DRM_DEBUG_KMS("failed to get ESI - device may have failed\n");
> - intel_dp->is_mst = false;
> - drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> - /* send a hotplug event */
> - drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
> + ret = drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
> + if (!handled)
> + return 0;
> +
> + if (ret)
> + DRM_DEBUG_KMS("error handling MST IRQ_HPD %d\n", ret);
> +
> + for (retry = 0; retry < 3; retry++) {
> + int wret;
> +
> + wret = drm_dp_dpcd_write(&intel_dp->aux,
> + DP_SINK_COUNT_ESI + 1, &esi[1],
> + 3);
> + if (wret == 3)
> + break;
> }
> }
> +
> + DRM_DEBUG_KMS("failed to get ESI - device may have failed\n");
> + intel_dp->is_mst = false;
> + drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr, intel_dp->is_mst);
> + drm_kms_helper_hotplug_event(intel_dig_port->base.base.dev);
> return -EINVAL;
> }
>
> --
> 2.11.0
>

--

James Ausmus