drm/i915/dsi: Do not clear DPOUNIT_CLOCK_GATE_DISABLE from vlv_init_display_clock_gating
commit bb98e72a upstream. On my Cherrytrail CUBE iwork8 Air tablet PIPE-A would get stuck on loading i915 at boot 1 out of every 3 boots, resulting in a non functional LCD. Once the i915 driver has successfully loaded, the panel can be disabled / enabled without hitting this issue. The getting stuck is caused by vlv_init_display_clock_gating() clearing the DPOUNIT_CLOCK_GATE_DISABLE bit in DSPCLK_GATE_D when called from chv_pipe_power_well_ops.enable() on driver load, while a pipe is enabled driving the DSI LCD by the BIOS. Clearing this bit while DSI is in use is a known issue and intel_dsi_pre_enable() / intel_dsi_post_disable() already set / clear it as appropriate. This commit modifies vlv_init_display_clock_gating() to leave the DPOUNIT_CLOCK_GATE_DISABLE bit alone fixing the pipe getting stuck. Changes in v2: -Replace PIPE-A with "a pipe" or "the pipe" in the commit msg and comment Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97330Signed-off-by: Hans de Goede <hdegoede@redhat.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161202142904.25613-1-hdegoede@redhat.comSigned-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (cherry picked from commit 721d4845) Signed-off-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: River Zhou <riverzhou2000@163.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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