On Wed, Oct 09, 2019 at 09:03:35PM -0600, Tuowen Zhao wrote: > Some BIOS erroneously specifies write-combining BAR for intel-lpss-pci > in MTRR. This will cause the system to hang during boot. If possible, > this bug could be corrected with a firmware update. > > This patch use devm_ioremap_uc to overwrite/ignore the MTRR settings > by forcing the use of strongly uncachable pages for intel-lpss. > > The BIOS bug is present on Dell XPS 13 7390 2-in-1: > > [ 0.001734] 5 base 4000000000 mask 6000000000 write-combining > > 4000000000-7fffffffff : PCI Bus 0000:00 > 4000000000-400fffffff : 0000:00:02.0 (i915) > 4010000000-4010000fff : 0000:00:15.0 (intel-lpss-pci) > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485 > Tested-by: AceLan Kao <acelan....@canonical.com> > Signed-off-by: Tuowen Zhao <ztuo...@gmail.com> > Acked-by: Mika Westerberg <mika.westerb...@linux.intel.com> > Acked-by: Andy Shevchenko <andriy.shevche...@linux.intel.com>
I think you'll want to Cc stable for this, as well as the last patch. LTS kernels with the ioremap_uc will be able to leverage the fix. Luis
