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) Link: https://bugzilla.kernel.org/show_bug.cgi?id=203485 Signed-off-by: Tuowen Zhao <[email protected]> --- 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
