Attachment 100718 Details for Bug 76520 – [PATCH] drm/i915: Avoid div-by-zero when pixel_multiplier is zero

[patch] [PATCH] drm/i915: Avoid div-by-zero when pixel_multiplier is zero

0001-drm-i915-Avoid-div-by-zero-when-pixel_multiplier-is-.patch (text/plain), 2.19 KB, created by Ville Syrjala on 2014-06-09 10:25:35 UTC

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Creator: Ville Syrjala

Created: 2014-06-09 10:25:35 UTC

Size: 2.19 KB

patch

obsolete

>From 55428c1bbd3ef3966e462e8d9b36c32ebb236682 Mon Sep 17 00:00:00 2001
>From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
>Date: Mon, 9 Jun 2014 13:17:19 +0300
>Subject: [PATCH] drm/i915: Avoid div-by-zero when pixel_multiplier is zero
>MIME-Version: 1.0
>Content-Type: text/plain; charset=UTF-8
>Content-Transfer-Encoding: 8bit
>
>On certain platforms pixel_multiplier is read out in
>.get_pipe_config(), but it also gets used to calculate the
>pixel clock in intel_sdvo_get_config(). If the pipe is disable
>but some SDVO outputs are active, we may end up dividing by zero
>in intel_sdvo_get_config().
>
>To avoid the problem simply check for zero pixel_multiplier and skip
>the division. Another attempt at fixing this involved populating
>pixel_multiplier to 1 even for disabled pipes, but that triggered a
>WARN because SDVO_CMD_GET_CLOCK_RATE_MULT command failed and thus
>encoder_pixel_multiplier was left at zero and didn't match
>pipe_config->pixel_multiplier.
>
>The "divide by pixel_multiplier" operation got introduced here:
> commit 18442d08786472c63a0a80c27f92b033dffc26de
> Author: Ville SyrjÃÂ¤lÃÂ¤ <ville.syrjala@linux.intel.com>
> Date:   Fri Sep 13 16:00:08 2013 +0300
>
>    drm/i915: Fix port_clock and adjusted_mode.clock readout all over
>
>and it has caused a regression on certain machines since they would
>hit the div-by-zero during resume.
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76520
>Cc: <stable@vger.kernel.org> # 3.13+
>Signed-off-by: Ville SyrjÃ¤lÃ¤ <ville.syrjala@linux.intel.com>
>---
> drivers/gpu/drm/i915/intel_sdvo.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
>index 6a4d5bc..20375cc 100644
>--- a/drivers/gpu/drm/i915/intel_sdvo.c
>+++ b/drivers/gpu/drm/i915/intel_sdvo.c
>@@ -1385,7 +1385,9 @@ static void intel_sdvo_get_config(struct intel_encoder *encoder,
> 			 >> SDVO_PORT_MULTIPLY_SHIFT) + 1;
> 	}
> 
>-	dotclock = pipe_config->port_clock / pipe_config->pixel_multiplier;
>+	dotclock = pipe_config->port_clock;
>+	if (pipe_config->pixel_multiplier)
>+		dotclock /= pipe_config->pixel_multiplier;
> 
> 	if (HAS_PCH_SPLIT(dev))
> 		ironlake_check_encoder_dotclock(pipe_config, dotclock);
>-- 
>1.8.5.5
>

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Attachments on bug 76520: 96282 | 97635 | 97636 | 97637 | 98841 | 100625 | 100674 | 100699 | 100714 | 100715 | 100718 | 100733

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