On Fri, 1 Feb 2019 at 06:55, Wu, Hao A <hao.a...@intel.com> wrote: > > > -----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. >
Acked-by: Ard Biesheuvel <ard.biesheu...@linaro.org> I think we should always prefer accessing MMIO registers using their native size, unless there are pressing reasons not to. > 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 > > > > _______________________________________________ > > edk2-devel mailing list > > edk2-devel@lists.01.org > > https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel