Re: [PATCH v2] dts64: mt7622: fix slow sd card access

[SkyLake Huang]

On Wed, 2021-01-13 at 19:09 +0100, Frank Wunderlich wrote:
> From: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
> 
> Fix extreme slow speed (200MB takes ~20 min) on writing sdcard on
> bananapi-r64 by adding reset-control for mmc1 like it's done for mmc0/emmc.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 2c002a3049f7 ("arm64: dts: mt7622: add mmc related device nodes")
> Signed-off-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
> ---
> changes since v1:
>  - drop change to uhs-mode because mt7622 does not support it
> ---
>  arch/arm64/boot/dts/mediatek/mt7622.dtsi | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt7622.dtsi b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> index 5b9ec032ce8d..7c6d871538a6 100644
> --- a/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt7622.dtsi
> @@ -698,6 +698,8 @@ mmc1: mmc@11240000 {
>  		clocks = <&pericfg CLK_PERI_MSDC30_1_PD>,
>  			 <&topckgen CLK_TOP_AXI_SEL>;
>  		clock-names = "source", "hclk";
> +		resets = <&pericfg MT7622_PERI_MSDC1_SW_RST>;
> +		reset-names = "hrst";
This looks ok to me. I think it's also necessary to trigger software
reset for SD(mmc1) because loader(uboot) might mess up MSDC's registers.
"Software reset" here will reset registers of AHB/AXI bus domain, such
as MSDC_CFG[8:15]. msdc_reset_hw() in mtk-sd.c will only reset registers
of MSDC CK domain.