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[AWS-B] UBUNTU: SAUCE: arm64: Enable PCI write-combine resources under sysfs

Message ID 20200902145018.13479-2-kamal@canonical.com
State New
Headers show
Series [AWS-B] UBUNTU: SAUCE: arm64: Enable PCI write-combine resources under sysfs | expand

Commit Message

Kamal Mostafa Sept. 2, 2020, 2:50 p.m. UTC 
From: Clint Sbisa <csbisa@amazon.com>

BugLink: https://bugs.launchpad.net/bugs/1893817

Using write-combine is crucial for performance of PCI devices where
significant amounts of transactions go over PCI BARs.

arm64 supports write-combine PCI mappings, so the appropriate define
has been added which will expose write-combine mappings under sysfs
for prefetchable PCI resources.

Signed-off-by: Clint Sbisa <csbisa@amazon.com>
Reference: https://lore.kernel.org/linux-pci/20200831151827.pumm2p54fyj7fz5s@amazon.com/
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/arm64/include/asm/pci.h | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h
index 8747f7c5e0e7..b4121784b4e8 100644
--- a/arch/arm64/include/asm/pci.h
+++ b/arch/arm64/include/asm/pci.h
@@ -23,6 +23,7 @@ 
  */
 #define PCI_DMA_BUS_IS_PHYS	(0)
 
+#define arch_can_pci_mmap_wc() 1
 #define ARCH_GENERIC_PCI_MMAP_RESOURCE	1
 
 extern int isa_dma_bridge_buggy;