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From: Val Kulkov <val.kulkov@gmail.com>
To: Imre Deak <imre.deak@intel.com>
Cc: intel-gfx@lists.freedesktop.org, wangqr <wqr.prg@gmail.com>
Subject: Re: [PATCH v2] drm/i915: Avoid HPD poll detect triggering a new detect cycle
Date: Mon, 28 Oct 2019 16:00:11 -0400	[thread overview]
Message-ID: <CABFXWOArh2fNzTJaVV33gBcALEX6NAvhdmbwT3nGJGKEnAzrzA@mail.gmail.com> (raw)
In-Reply-To: <20191028181517.22602-1-imre.deak@intel.com>

On Mon, 28 Oct 2019 at 14:16, Imre Deak <imre.deak@intel.com> wrote:
>
> For the HPD interrupt functionality the HW depends on power wells in the
> display core domain to be on. Accordingly when enabling these power
> wells the HPD polling logic will force an HPD detection cycle to account
> for hotplug events that may have happened when such a power well was
> off.
>
> Thus a detect cycle started by polling could start a new detect cycle if
> a power well in the display core domain gets enabled during detect and
> stays enabled after detect completes. That in turn can lead to a
> detection cycle runaway.
>
> To prevent re-triggering a poll-detect cycle make sure we drop all power
> references we acquired during detect synchronously by the end of detect.
> This will let the poll-detect logic continue with polling (matching the
> off state of the corresponding power wells) instead of scheduling a new
> detection cycle.
>
> Fixes: 6cfe7ec02e85 ("drm/i915: Remove the unneeded AUX power ref from intel_dp_detect()")
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112125
> Reported-and-tested-by: Val Kulkov <val.kulkov@gmail.com>
> Reported-and-tested-by: wangqr <wqr.prg@gmail.com>
> Cc: Val Kulkov <val.kulkov@gmail.com>
> Cc: wangqr <wqr.prg@gmail.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Confirming that this latest revision of the patch fixes the issue.
Tested on linux-drm-tip-git
5.4.865162.dd5bccfa3b5d-1 on Eglobal NUC Fanless Mini PC Intel N3150.
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

WARNING: multiple messages have this Message-ID (diff)
From: Val Kulkov <val.kulkov@gmail.com>
To: Imre Deak <imre.deak@intel.com>
Cc: intel-gfx@lists.freedesktop.org, wangqr <wqr.prg@gmail.com>
Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: Avoid HPD poll detect triggering a new detect cycle
Date: Mon, 28 Oct 2019 16:00:11 -0400	[thread overview]
Message-ID: <CABFXWOArh2fNzTJaVV33gBcALEX6NAvhdmbwT3nGJGKEnAzrzA@mail.gmail.com> (raw)
Message-ID: <20191028200011.lkwK8wRZ8UM4Iof8tfyUPNKrhXbBerejbswqdoaT_6c@z> (raw)
In-Reply-To: <20191028181517.22602-1-imre.deak@intel.com>

On Mon, 28 Oct 2019 at 14:16, Imre Deak <imre.deak@intel.com> wrote:
>
> For the HPD interrupt functionality the HW depends on power wells in the
> display core domain to be on. Accordingly when enabling these power
> wells the HPD polling logic will force an HPD detection cycle to account
> for hotplug events that may have happened when such a power well was
> off.
>
> Thus a detect cycle started by polling could start a new detect cycle if
> a power well in the display core domain gets enabled during detect and
> stays enabled after detect completes. That in turn can lead to a
> detection cycle runaway.
>
> To prevent re-triggering a poll-detect cycle make sure we drop all power
> references we acquired during detect synchronously by the end of detect.
> This will let the poll-detect logic continue with polling (matching the
> off state of the corresponding power wells) instead of scheduling a new
> detection cycle.
>
> Fixes: 6cfe7ec02e85 ("drm/i915: Remove the unneeded AUX power ref from intel_dp_detect()")
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112125
> Reported-and-tested-by: Val Kulkov <val.kulkov@gmail.com>
> Reported-and-tested-by: wangqr <wqr.prg@gmail.com>
> Cc: Val Kulkov <val.kulkov@gmail.com>
> Cc: wangqr <wqr.prg@gmail.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>

Confirming that this latest revision of the patch fixes the issue.
Tested on linux-drm-tip-git
5.4.865162.dd5bccfa3b5d-1 on Eglobal NUC Fanless Mini PC Intel N3150.
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  reply	other threads:[~2019-10-28 20:00 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-28 11:00 [PATCH] drm/i915: Avoid HPD poll detect triggering a new detect cycle Imre Deak
2019-10-28 11:00 ` [Intel-gfx] " Imre Deak
2019-10-28 13:56 ` ✗ Fi.CI.CHECKPATCH: warning for " Patchwork
2019-10-28 13:56   ` [Intel-gfx] " Patchwork
2019-10-28 14:17 ` ✓ Fi.CI.BAT: success " Patchwork
2019-10-28 14:17   ` [Intel-gfx] " Patchwork
2019-10-28 17:27 ` [PATCH] " Val Kulkov
2019-10-28 17:27   ` [Intel-gfx] " Val Kulkov
2019-10-28 17:45 ` Ville Syrjälä
2019-10-28 17:45   ` [Intel-gfx] " Ville Syrjälä
2019-10-28 18:06   ` Imre Deak
2019-10-28 18:06     ` [Intel-gfx] " Imre Deak
2019-10-28 18:15 ` [PATCH v2] " Imre Deak
2019-10-28 18:15   ` [Intel-gfx] " Imre Deak
2019-10-28 20:00   ` Val Kulkov [this message]
2019-10-28 20:00     ` Val Kulkov
2019-10-30 14:03   ` Ville Syrjälä
2019-10-30 14:03     ` [Intel-gfx] " Ville Syrjälä
2019-10-28 22:01 ` ✗ Fi.CI.BAT: failure for drm/i915: Avoid HPD poll detect triggering a new detect cycle (rev2) Patchwork
2019-10-28 22:01   ` [Intel-gfx] " Patchwork
2019-10-28 22:42   ` Imre Deak
2019-10-28 22:42     ` [Intel-gfx] " Imre Deak
2019-10-29  9:13 ` ✓ Fi.CI.IGT: success for drm/i915: Avoid HPD poll detect triggering a new detect cycle Patchwork
2019-10-29  9:13   ` [Intel-gfx] " Patchwork
2019-10-29 10:26 ` ✗ Fi.CI.BAT: failure for drm/i915: Avoid HPD poll detect triggering a new detect cycle (rev2) Patchwork
2019-10-29 10:26   ` [Intel-gfx] " Patchwork
2019-10-29 13:01 ` ✓ Fi.CI.BAT: success " Patchwork
2019-10-29 13:01   ` [Intel-gfx] " Patchwork
2019-10-30  0:06 ` ✓ Fi.CI.IGT: " Patchwork
2019-10-30  0:06   ` [Intel-gfx] " Patchwork
2019-10-30 14:39   ` Imre Deak
2019-10-30 14:39     ` [Intel-gfx] " Imre Deak

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