diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2014-06-09 16:20:46 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-09 11:21:26 -0700 |
| commit | 6b295013155ab6cd4cf29dcf741f198aa36e931e (patch) | |
| tree | 10233cd28065c14d8dc904ad66fbf25bcba22612 | |
| parent | f4db98240ac2c6d9d2118c6f82d483ff5293f1ed (diff) | |
drm/i915: Avoid div-by-zero when pixel_multiplier is zero
commit 2b85886a5457f5c5dbcd32edbd4e6bba0f4e8678 upstream.
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 Syrjälä <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
Tested-by: Tim Richardson <tim@tim-richardson.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/gpu/drm/i915/intel_sdvo.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c index 46be00d66df..6317953d577 100644 --- a/drivers/gpu/drm/i915/intel_sdvo.c +++ b/drivers/gpu/drm/i915/intel_sdvo.c @@ -1383,7 +1383,9 @@ 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); |