APPLIED[AWS-B]: [PATCHv2][AWS-B] UBUNTU: SAUCE: arm64: Enable PCI write-combine resources under sysfs

[Ian May]

Applied to aws-bionic.  

Thanks!
Ian

On 2020-10-07 13:11:19 , Kamal Mostafa wrote:
> From: Clint Sbisa <csbisa at 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 at amazon.com>
> Reference: https://lore.kernel.org/linux-pci/20200831151827.pumm2p54fyj7fz5s@amazon.com/
> Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> Acked-by: Stefan Bader <stefan.bader at canonical.com>                             
> Acked-by: Andrea Righi <andrea.righi at canonical.com>                             
> ---
>  arch/arm64/include/asm/pci.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> 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;
> -- 
> 2.17.1
> 
> -- 
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