Re: [PATCH v3] drm/i915: intel_hpd_init(): Fix suspend/resume reprobing

Daniel Vetter
2016-01-07T16:11:01Z

On Thu, Jan 07, 2016 at 10:43:28AM -0500, Lyude wrote:
> This fixes reprobing of display connectors on resume. After some
> talking with danvet on IRC, I learned that calling
> drm_helper_hpd_irq_event() does actually trigger a full reprobe of each
> connector's status. It turns out this is the actual reason reprobing on
> resume hasn't been working (this was observed on a T440s):
>
> - We call hpd_init()
> - We check each connector for a couple of things before marking
> connector->polled with DRM_CONNECTOR_POLL_HPD, one of which is an
> active encoder. Of course, a disconnected port won't have an
> active encoder, so we don't add the flag to any of the
> connectors.
> - We call drm_helper_hpd_irq_event()
> - drm_helper_irq_event() checks each connector for the
> DRM_CONNECTOR_POLL_HPD flag. The only one that has it is eDP-1,
> so we skip reprobing each connector except that one.
>
> In addition, we also now avoid setting connector->polled to
> DRM_CONNECTOR_POLL_HPD for MST connectors, since their reprobing is
> handled by the mst helpers. This is probably what was originally
> intended to happen here.
>
> Changes since V1:
> * Use the explanation of the issue as the commit message instead
> * Change the title of the commit, since this does more then just stop a
> check for an encoder now
> * Add "Fixes" line for the patch that introduced this regression
> * Don't enable DRM_CONNECTOR_POLL_HPD for mst connectors
>
> Changes since V2:
> * Put patch changelog above Signed-off-by
> * Follow Daniel Vetter's suggestion for making the code here a bit more
> legible
>
> Fixes: 0e32b39ceed6 ("drm/i915: add DP 1.2 MST support (v0.7)")
> Cc: stable@vger.kernel.org
> Signed-off-by: Lyude <cpaul@redhat.com>

Awesome, and merged to drm-intel.

Thanks, Daniel

> ---
> drivers/gpu/drm/i915/intel_hotplug.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_hotplug.c b/drivers/gpu/drm/i915/intel_hotplug.c
> index b177857..d7a6437 100644
> --- a/drivers/gpu/drm/i915/intel_hotplug.c
> +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> @@ -468,9 +468,14 @@ void intel_hpd_init(struct drm_i915_private *dev_priv)
> list_for_each_entry(connector, &mode_config->connector_list, head) {
> struct intel_connector *intel_connector = to_intel_connector(connector);
> connector->polled = intel_connector->polled;
> - if (connector->encoder && !connector->polled && I915_HAS_HOTPLUG(dev) && intel_connector->encoder->hpd_pin > HPD_NONE)
> - connector->polled = DRM_CONNECTOR_POLL_HPD;
> +
> + /* MST has a dynamic intel_connector->encoder and it's reprobing
> + * is all handled by the MST helpers. */
> if (intel_connector->mst_port)
> + continue;
> +
> + if (!connector->polled && I915_HAS_HOTPLUG(dev) &&
> + intel_connector->encoder->hpd_pin > HPD_NONE)
> connector->polled = DRM_CONNECTOR_POLL_HPD;
> }
>
> --
> 2.5.0
>
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