> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-boun...@lists.01.org] On Behalf Of Jeff
> Brasen
> Sent: Thursday, January 31, 2019 7:59 AM
> To: edk2-devel@lists.01.org
> Cc: Edgar Handal; Jeff Brasen
> Subject: [edk2] [PATCH] MdeModulePkg/SdMmcPciHcDxe: Use 16/32-bit IO
> widths
>
> From: Edgar Handal <ehan...@nvidia.com>
>
> Use 16-bit and 32-bit IO widths for SDMMC MMIO to prevent all register
> accesses from being split up into 8-bit accesses.
>
> The SDHCI specification states that the registers shall be accessable in
> byte, word, and double word accesses.
Hi,
Thanks for the contribution. The change seems good to me.
Just curious, if the accesses are always slit into byte(8-bit), is there any
issue or performance impact is encountered during your usage?
It will be helpful to get more information on the purpose of the patch.
Thanks.
Best Regards,
Hao Wu
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Jeff Brasen <jbra...@nvidia.com>
> ---
> MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHci.c | 25
> ++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHci.c
> b/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHci.c
> index 5aec8c6..82f4493 100644
> --- a/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHci.c
> +++ b/MdeModulePkg/Bus/Pci/SdMmcPciHcDxe/SdMmcPciHci.c
> @@ -152,19 +152,36 @@ SdMmcHcRwMmio (
> )
> {
> EFI_STATUS Status;
> + EFI_PCI_IO_PROTOCOL_WIDTH Width;
>
> if ((PciIo == NULL) || (Data == NULL)) {
> return EFI_INVALID_PARAMETER;
> }
>
> - if ((Count != 1) && (Count != 2) && (Count != 4) && (Count != 8)) {
> - return EFI_INVALID_PARAMETER;
> + switch (Count) {
> + case 1:
> + Width = EfiPciIoWidthUint8;
> + break;
> + case 2:
> + Width = EfiPciIoWidthUint16;
> + Count = 1;
> + break;
> + case 4:
> + Width = EfiPciIoWidthUint32;
> + Count = 1;
> + break;
> + case 8:
> + Width = EfiPciIoWidthUint32;
> + Count = 2;
> + break;
> + default:
> + return EFI_INVALID_PARAMETER;
> }
>
> if (Read) {
> Status = PciIo->Mem.Read (
> PciIo,
> - EfiPciIoWidthUint8,
> + Width,
> BarIndex,
> (UINT64) Offset,
> Count,
> @@ -173,7 +190,7 @@ SdMmcHcRwMmio (
> } else {
> Status = PciIo->Mem.Write (
> PciIo,
> - EfiPciIoWidthUint8,
> + Width,
> BarIndex,
> (UINT64) Offset,
> Count,
> --
> 2.7.4
>
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