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Message-ID: <20151210075907.GR20822@phenom.ffwll.local>
Date: Thu, 10 Dec 2015 08:59:07 +0100
From: Daniel Vetter <daniel@...ll.ch>
To: Stefan Lippers-Hollmann <s.l-h@....de>
Cc: Dave Airlie <airlied@...ux.ie>,
DRI mailing list <dri-devel@...ts.freedesktop.org>,
linux-kernel@...r.kernel.org,
Sonika Jindal <sonika.jindal@...el.com>,
Shashank Sharma <shashank.sharma@...el.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Daniel Vetter <daniel.vetter@...ll.ch>
Subject: Re: [git pull] drm for 4.4-rc1
On Thu, Dec 10, 2015 at 04:04:20AM +0100, Stefan Lippers-Hollmann wrote:
> Hi
>
> On 2015-11-09, Dave Airlie wrote:
> [...]
> The following changes since commit 06d1ee32a4d25356a710b49d5e95dbdd68bdf505:
>
> Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux (2015-10-13 09:45:21 -0700)
>
> are available in the git repository at:
>
> git://people.freedesktop.org/~airlied/linux drm-next
>
> for you to fetch changes up to 816d2206f0f9953ca854e4ff1a2749a5cbd62715:
>
> Merge tag 'drm-intel-next-fixes-2015-11-06' of git://anongit.freedesktop.org/drm-intel into drm-next (2015-11-07 17:16:59 +1000)
> [...]
> > drm/i915: Check live status before reading edid
> [...]
>
> This patch seems to introduce a regression for i915 in Linus'
> v4.4-rc4-60-g9a0f76f, relative to v4.3 (and 4.3.1), on a sandy-bridge
> (Intel DH67CL) system with a single HDMI connected monitor (Medion MD20094)
> attached. Immediately after the modeswitch, the monitor switches off and
> stays off. Nothing catches my eyes in dmesg or Xorg.0.log, but bisecting
> the issue points me at:
>
> 237ed86c693d8a8e4db476976aeb30df4deac74b is the first bad commit
> commit 237ed86c693d8a8e4db476976aeb30df4deac74b
> Author: Sonika Jindal <sonika.jindal@...el.com>
> Date: Tue Sep 15 09:44:20 2015 +0530
>
> drm/i915: Check live status before reading edid
>
> The Bspec is very clear that Live status must be checked about before
> trying to read EDID over DDC channel. This patch makes sure that HDMI
> EDID is read only when live status is up.
>
> The live status doesn't seem to perform very consistent across various
> platforms when tested with different monitors. The reason behind that is
> some monitors are late to provide right voltage to set live_status up.
> So, after getting the interrupt, for a small duration, live status reg
> fluctuates, and then settles down showing the correct staus.
>
> This is explained here in, in a rough way:
> HPD line ________________
> |\ T1 = Monitor Hotplug causing IRQ
> | \______________________________________
> | |
> | |
> | | T2 = Live status is stable
> | | _____________________________________
> | | /|
> Live status _____________|_|/ |
> | | |
> | | |
> | | |
> T0 T1 T2
>
> (Between T1 and T2 Live status fluctuates or can be even low, depending on
> the monitor)
>
> After several experiments, we have concluded that a max delay
> of 30ms is enough to allow the live status to settle down with
> most of the monitors. This total delay of 30ms has been split into
> a resolution of 3 retries of 10ms each, for the better cases.
>
> This delay is kept at 30ms, keeping in consideration that, HDCP compliance
> expect the HPD handler to respond a plug out in 100ms, by disabling port.
>
> v2: Adding checks for VLV/CHV as well. Reusing old ibx and g4x functions
> to check digital port status. Adding a separate function to get bxt live
> status (Daniel)
> v3: Using intel_encoder->hpd_pin to check the live status (Siva)
> Moving the live status read to intel_hdmi_probe and passing parameter
> to read/not to read the edid. (me)
> v4:
> * Added live status check for all platforms using
> intel_digital_port_connected.
> * Rebased on top of Jani's DP cleanup series
> * Some monitors take time in setting the live status. So retry for few
> times if this is a connect HPD
> v5: Removed extra "drm/i915" from commit message. Adding Shashank's sob
> which was missed.
> v6: Drop the (!detect_edid && !live_status check) check because for DDI
> ports which are enumerated as hdmi as well as DP, we don't have a
> mechanism to differentiate between DP and hdmi inside the encoder's
> hot_plug. This leads to call to the hdmi's hot_plug hook for DP as well
> as hdmi which leads to issues during unplug because of the above check.
> v7: Make intel_digital_port_connected global in this patch, some
> reformatting of while loop, adding a print when live status is not
> up. (Rodrigo)
> v8: Rebase it on nightly which involved skipping the hot_plug hook for now
> and letting the live_status check happen in detect until the hpd handling
> part is finalized (Daniel)
>
> Signed-off-by: Shashank Sharma <shashank.sharma@...el.com>
> Signed-off-by: Sonika Jindal <sonika.jindal@...el.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
>
> :040000 040000 85f19ff45ffe39cee99a7a9b0e9dadf9fe71553f 0094b6c634580a496c5cdbf77f13fe5fa769c3e3 M drivers
>
> $ git bisect log
> # bad: [9a0f76fde9ad2c00c0cf13aaf3dfb9d886dc578c] Merge tag 'for-linus-4.4-1' of git://git.code.sf.net/p/openipmi/linux-ipmi
> # good: [6a13feb9c82803e2b815eca72fa7a9f5561d7861] Linux 4.3
> git bisect start 'HEAD' 'v4.3'
> # good: [8e483ed1342a4ea45b70f0f33ac54eff7a33d918] Merge tag 'char-misc-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
> git bisect good 8e483ed1342a4ea45b70f0f33ac54eff7a33d918
> # bad: [3e82806b97398d542a5e03bd94861f79ce10ecee] Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
> git bisect bad 3e82806b97398d542a5e03bd94861f79ce10ecee
> # good: [0280d1a099da1d211e76ec47cc0944c993a36316] Merge tag 'sound-4.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
> git bisect good 0280d1a099da1d211e76ec47cc0944c993a36316
> # good: [123a28d8b522b03dd97c1f791245924088616ac0] Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
> git bisect good 123a28d8b522b03dd97c1f791245924088616ac0
> # bad: [b10f1b20171945b49988b2b1fe68cb312cc36d32] drm/i915/skl: Prevent unclaimed register writes on skylake.
> git bisect bad b10f1b20171945b49988b2b1fe68cb312cc36d32
> # bad: [89e3e1427629027dc33e576fc002880a02a7e50c] drm/i915: Support NV12 in rotated GGTT mapping
> git bisect bad 89e3e1427629027dc33e576fc002880a02a7e50c
> # good: [0b2eb33e5e2b4aaeaa786d551a1b5f08904a9bfc] drm/i915: LPT:LP needs port A HPD enabled in both north and south
> git bisect good 0b2eb33e5e2b4aaeaa786d551a1b5f08904a9bfc
> # good: [eb120ef6a3e18780e7464e7de70221d06dfe5845] drm/i915: add more debug info for when atomic updates fail v3
> git bisect good eb120ef6a3e18780e7464e7de70221d06dfe5845
> # bad: [7aefe2b50a0be5c85e7702bff110e5e187fbe4b5] drm/i915: Fix fastboot scalers for skylake.
> git bisect bad 7aefe2b50a0be5c85e7702bff110e5e187fbe4b5
> # good: [83e3337204b2385d20e149c8fe91bb2719978df2] drm/i915: Increase maximum polling time to 50ms for forcewake request/clear ack
> git bisect good 83e3337204b2385d20e149c8fe91bb2719978df2
> # bad: [9eca6832f7254d49d25494da7d47c0f8a24f7862] drm/i915: Move scanline_offset and timestamping constant setup to intel_modeset_readout_hw_state()
> git bisect bad 9eca6832f7254d49d25494da7d47c0f8a24f7862
> # good: [d2e08c0f34438af791482de8abf2c8e4e573b1d3] drm/i915/bxt: DSI prepare changes for BXT
> git bisect good d2e08c0f34438af791482de8abf2c8e4e573b1d3
> # bad: [7f4c62840cc416986f983a8c68f7010c97e06daf] drm/i915: Assign hwmode after encoder state readout
> git bisect bad 7f4c62840cc416986f983a8c68f7010c97e06daf
> # bad: [237ed86c693d8a8e4db476976aeb30df4deac74b] drm/i915: Check live status before reading edid
> git bisect bad 237ed86c693d8a8e4db476976aeb30df4deac74b
> # first bad commit: [237ed86c693d8a8e4db476976aeb30df4deac74b] drm/i915: Check live status before reading edid
>
> Unfortunately reverting only this patch on top of v4.4-rc4-60-g9a0f76f
> doesn't appear to be quite straight forward. What is the best approach
> to debug this further?
>
> The very same kernel works fine on two ivy-bridge systems (different
> monitors, one connected via HDMI, one via DVI) and an Atom N270 based
> system (Intel D945GSEJT, monitor connected via DVI).
A few things to test:
- How does that screen fare on a working machine? Would tell us if the
issue is with the sink or the source.
- Please boot up with drm.debug=0xe on a working and broken kernel, grab
dmesg for both.
- Extending the timeout magic might be worth a shot like in the below
patch. Crank up retry if it doesn't help.
Thanks, Daniel
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index c3978bad5ca0..86ebaac548b3 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1387,7 +1387,7 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
struct drm_i915_private *dev_priv = to_i915(connector->dev);
bool live_status = false;
- unsigned int retry = 3;
+ unsigned int retry = 10;
DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
connector->base.id, connector->name);
@@ -1397,7 +1397,7 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
while (!live_status && --retry) {
live_status = intel_digital_port_connected(dev_priv,
hdmi_to_dig_port(intel_hdmi));
- mdelay(10);
+ msleep(10);
}
if (!live_status)
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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