From 4b74251368e136095a2096ea1bdf95d40ddbd7fb Mon Sep 17 00:00:00 2001 From: Tuowen Zhao Date: Wed, 16 Oct 2019 15:06:29 -0600 Subject: [PATCH 03/16] mfd: intel-lpss: Use devm_ioremap_uc for MMIO 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: # v4.19+ Tested-by: AceLan Kao Signed-off-by: Tuowen Zhao Acked-by: Mika Westerberg Acked-by: Andy Shevchenko Tested-by: Roman Gilg Signed-off-by: Lee Jones --- 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; -- 2.24.1