On Thu, Oct 17, 2019 at 7:48 PM Tuowen Zhao <[email protected]> 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 > Cc: <[email protected]> > Tested-by: AceLan Kao <[email protected]> > Signed-off-by: Tuowen Zhao <[email protected]> > Acked-by: Mika Westerberg <[email protected]> > Acked-by: Andy Shevchenko <[email protected]> > Acked-for-MFD-by: Lee Jones <[email protected]> > --- > drivers/mfd/intel-lpss.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/mfd/intel-lpss.c b/drivers/mfd/intel-lpss.c > index bfe4ff337581..b0f0781a6b9c 100644 > --- a/drivers/mfd/intel-lpss.c > +++ b/drivers/mfd/intel-lpss.c > @@ -384,7 +384,7 @@ int intel_lpss_probe(struct device *dev, > if (!lpss) > return -ENOMEM; > > - lpss->priv = devm_ioremap(dev, info->mem->start + LPSS_PRIV_OFFSET, > + lpss->priv = devm_ioremap_uc(dev, info->mem->start + LPSS_PRIV_OFFSET, > LPSS_PRIV_SIZE); > if (!lpss->priv) > return -ENOMEM; > -- > 2.23.0 >
Tested this v5 series on an XPS 13 7390 2-in-1 with Manjaro/KDE install and works fine there. Fixes hang during boot. Currently being backported to 5.3 on that distro: https://gitlab.manjaro.org/packages/core/linux53/commit/c00ddfb5 Tested-by: Roman Gilg <[email protected]>
