Re: [Bug #14380] Video tearing/glitching with T400 laptops

Arkadiusz Miskiewicz
2009-11-17T12:52:19Z

On Monday 16 of November 2009, Rafael J. Wysocki wrote:
> This message has been generated automatically as a part of a report
> of recent regressions.
>
> The following bug entry is on the current list of known regressions
> from 2.6.31. Please verify if it still should be listed and let me know
> (either way).

It's mostly gone. It still happens for like 1/4s once per 6hours but jbarnes
asked me to fill separate bug for that and gave such patch for testing (see below).

So far haven't seen 1/4s problem with this patch applied.

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3ba6546..b2cbf7f 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2491,6 +2491,8 @@ static void g4x_update_wm(struct drm_device *dev, int planea_clock,
/* Use ns/us then divide to preserve precision */
sr_entries = (((sr_latency_ns / line_time_us) + 1) *
pixel_size * sr_hdisplay) / 1000;
+ if (sr_entries > G4X_FIFO_SIZE)
+ sr_entries = G4X_FIFO_SIZE;
sr_entries = roundup(sr_entries / cacheline_size, 1);
DRM_DEBUG("self-refresh entries: %d\n", sr_entries);
I915_WRITE(FW_BLC_SELF, FW_BLC_SELF_EN);

>
>
> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=14380
> Subject : Video tearing/glitching with T400 laptops
> Submitter : Theodore Ts'o <tytso@mit.edu>
> Date : 2009-10-02 22:40 (46 days old)
> References : http://marc.info/?l=linux-kernel&m=125452324520623&w=4
> Handled-By : Jesse Barnes <jbarnes@virtuousgeek.org>
> Patch : http://marc.info/?l=linux-kernel&m=125591495325000&w=4
>

--
Arkadiusz Miśkiewicz PLD/Linux Team
arekm / maven.pl http://ftp.pld-linux.org/