Re: [PATCH edk2-platforms] Silicon/SynQuacer/PlatformDxe: disable eMMC DDR50 support

[Leif Lindholm <leif.lindholm@linaro.org>]

On Thu, Feb 08, 2018 at 10:18:12AM +0000, Ard Biesheuvel wrote:
> We already disable SDR104 support on the SynQuacer eMMC controller to
> work around the need for a special tuning quirk that is difficult to
> implement without modifying the generic driver, even in the presence
> of a SD/MMC override protocol designed to carry such quirks.
> 
> Unfortunately, as it turns out, DDR50 does not work either with the
> particular 8 GB Kingston part that has been fitted on the rev0.2/0.3
> 96board samples. Since the mode UEFI drives the eMMC in is independent
> from what the OS chooses, and the fact that you would not use eMMC in
> the first place if performance was a major concern, let's just disable
> DDR50 as well, and fall back to SDR50 mode.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
>  Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Emmc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Emmc.c b/Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Emmc.c
> index c40b30929d5d..6875dfe6b319 100644
> --- a/Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Emmc.c
> +++ b/Silicon/Socionext/SynQuacer/Drivers/PlatformDxe/Emmc.c
> @@ -52,6 +52,7 @@
>  #define SYNQUACER_CLOCK_CTRL_VAL  0xBC01
>  
>  #define SD_HC_CAP_SDR104          BIT33
> +#define SD_HC_CAP_DDR50           BIT34
>  
>  #define ESD_CONTROL_RESET_DELAY   (20 * 1000)
>  #define IO_CONTROL2_SETTLE_US     3000
> @@ -95,7 +96,7 @@ SynQuacerSdMmcCapability (
>    // quirk that is difficult to support using the generic driver.
>    //
>    Capability = ReadUnaligned64 (SdMmcHcSlotCapability);
> -  Capability &= ~(UINT64)SD_HC_CAP_SDR104;
> +  Capability &= ~(UINT64)(SD_HC_CAP_SDR104 | SD_HC_CAP_DDR50);
>    WriteUnaligned64 (SdMmcHcSlotCapability, Capability);
>  
>    return EFI_SUCCESS;
> -- 
> 2.11.0
>