On Mon, Oct 07, 2019 at 12:42:31PM -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 adds devm_ioremap_uc as a new managed wrapper to ioremap_uc > and with it overwrite the MTRR settings to force 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) >
Acked-by: Andy Shevchenko <andriy.shevche...@linux.intel.com> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485 > Signed-off-by: Tuowen Zhao <ztuo...@gmail.com> > --- > Changes from previous version: > > * changed commit message > > drivers/mfd/intel-lpss.c | 2 +- > include/linux/io.h | 2 ++ > lib/devres.c | 19 +++++++++++++++++++ > 3 files changed, 22 insertions(+), 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; > diff --git a/include/linux/io.h b/include/linux/io.h > index accac822336a..a59834bc0a11 100644 > --- a/include/linux/io.h > +++ b/include/linux/io.h > @@ -64,6 +64,8 @@ static inline void devm_ioport_unmap(struct device *dev, > void __iomem *addr) > > void __iomem *devm_ioremap(struct device *dev, resource_size_t offset, > resource_size_t size); > +void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset, > + resource_size_t size); > void __iomem *devm_ioremap_nocache(struct device *dev, resource_size_t > offset, > resource_size_t size); > void __iomem *devm_ioremap_wc(struct device *dev, resource_size_t offset, > diff --git a/lib/devres.c b/lib/devres.c > index 6a0e9bd6524a..beb0a064b891 100644 > --- a/lib/devres.c > +++ b/lib/devres.c > @@ -9,6 +9,7 @@ > enum devm_ioremap_type { > DEVM_IOREMAP = 0, > DEVM_IOREMAP_NC, > + DEVM_IOREMAP_UC, > DEVM_IOREMAP_WC, > }; > > @@ -39,6 +40,9 @@ static void __iomem *__devm_ioremap(struct device *dev, > resource_size_t offset, > case DEVM_IOREMAP_NC: > addr = ioremap_nocache(offset, size); > break; > + case DEVM_IOREMAP_UC: > + addr = ioremap_uc(offset, size); > + break; > case DEVM_IOREMAP_WC: > addr = ioremap_wc(offset, size); > break; > @@ -68,6 +72,21 @@ void __iomem *devm_ioremap(struct device *dev, > resource_size_t offset, > } > EXPORT_SYMBOL(devm_ioremap); > > +/** > + * devm_ioremap_uc - Managed ioremap_uc() > + * @dev: Generic device to remap IO address for > + * @offset: Resource address to map > + * @size: Size of map > + * > + * Managed ioremap_uc(). Map is automatically unmapped on driver detach. > + */ > +void __iomem *devm_ioremap_uc(struct device *dev, resource_size_t offset, > + resource_size_t size) > +{ > + return __devm_ioremap(dev, offset, size, DEVM_IOREMAP_UC); > +} > +EXPORT_SYMBOL(devm_ioremap_uc); > + > /** > * devm_ioremap_nocache - Managed ioremap_nocache() > * @dev: Generic device to remap IO address for > -- > 2.23.0 > -- With Best Regards, Andy Shevchenko
