On Wed, Feb 13, 2019 at 04:47:34PM +0200, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
Certain SNB machines (eg. ASUS K53SV) seem to have a broken BIOS which misprograms the hardware badly when encountering a suitably high resolution display. The programmed pipe timings are somewhat bonkers and the DPLL is totally misprogrammed (P divider == 0). That will result in atomic commit timeouts as apparently the pipe is sufficiently stuck to not signal vblank interrupts.
IIRC something like this was also observed on some other SNB machine years ago (might have been a Dell XPS 8300) but a BIOS update cured it. Sadly looks like this was never fixed for the ASUS K53SV as the latest BIOS (K53SV.320 11/11/2011) is still broken.
The quickest way to deal with this seems to be to shut down the pipe+ports+DPLL. Unfortunately doing this during the normal sanitization phase isn't quite soon enough as we already spew several WARNs about the bogus hardware state. But it's better than hanging the boot for a few dozen seconds. Since this is limited to a few old machines it doesn't seem entirely worthwile to try and rework the readout+sanitization code to handle it more gracefully.
v2: Fix potential NULL deref (kbuild test robot) Constify has_bogus_dpll_config()
Cc: stable@vger.kernel.org # v4.20+ Cc: Daniel Kamil Kozar dkk089@gmail.com Reported-by: Daniel Kamil Kozar dkk089@gmail.com Tested-by: Daniel Kamil Kozar dkk089@gmail.com Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109245 Fixes: 516a49cc1946 ("drm/i915: Fix assert_plane() warning on bootup with external display") Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190111174950.10681-1-ville.s... Reviewed-by: Mika Kahola mika.kahola@intel.com (cherry picked from commit 7bed8adcd9f86231bb69bbc02f88ad89330f99e3) Signed-off-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190205141846.6053-1-ville.sy... (cherry picked from commit d028a646e84b9b131e4ff2cb5bbdd3825d141028)
Now queued up, thanks.
greg k-h