From 2b85886a5457f5c5dbcd32edbd4e6bba0f4e8678 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Mon, 9 Jun 2014 16:20:46 +0300 Subject: [PATCH] drm/i915: Avoid div-by-zero when pixel_multiplier is zero MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 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 Syrjälä 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: # 3.13+ Tested-by: Tim Richardson Reviewed-by: Daniel Vetter Signed-off-by: Ville Syrjälä Signed-off-by: Jani Nikula --- Reading git-format-patch failed