[PATCH] ARM: dts: rockchip: set dw_mmc max-freq 150Mhz

[PATCH] ARM: dts: rockchip: set dw_mmc max-freq 150Mhz

[Addy Ke]

All of mmc controllers include SDMMC, SDIO0, SDIO1, and EMMC on RK3288
are limited to 150Mhz. It was mainly caused by two reasons:
- RK3288's IO pad(except DDR IO pad) is generic, which can only support
  the max of 150Mhz.
- Mmc controller was designed at 150Mhz, and the pressure test by IC team
  was based on this freequency point.

Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
---
 arch/arm/boot/dts/rk3288.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/rk3288.dtsi b/arch/arm/boot/dts/rk3288.dtsi
index acb6a2f..9c35a1d 100644
--- a/arch/arm/boot/dts/rk3288.dtsi
+++ b/arch/arm/boot/dts/rk3288.dtsi
@@ -149,6 +149,7 @@
 
 	sdmmc: dwmmc at ff0c0000 {
 		compatible = "rockchip,rk3288-dw-mshc";
+		clock-freq-min-max = <400000 150000000>;
 		clocks = <&cru HCLK_SDMMC>, <&cru SCLK_SDMMC>;
 		clock-names = "biu", "ciu";
 		fifo-depth = <0x100>;
@@ -159,6 +160,7 @@
 
 	sdio0: dwmmc at ff0d0000 {
 		compatible = "rockchip,rk3288-dw-mshc";
+		clock-freq-min-max = <400000 150000000>;
 		clocks = <&cru HCLK_SDIO0>, <&cru SCLK_SDIO0>;
 		clock-names = "biu", "ciu";
 		fifo-depth = <0x100>;
@@ -169,6 +171,7 @@
 
 	sdio1: dwmmc at ff0e0000 {
 		compatible = "rockchip,rk3288-dw-mshc";
+		clock-freq-min-max = <400000 150000000>;
 		clocks = <&cru HCLK_SDIO1>, <&cru SCLK_SDIO1>;
 		clock-names = "biu", "ciu";
 		fifo-depth = <0x100>;
@@ -179,6 +182,7 @@
 
 	emmc: dwmmc at ff0f0000 {
 		compatible = "rockchip,rk3288-dw-mshc";
+		clock-freq-min-max = <400000 150000000>;
 		clocks = <&cru HCLK_EMMC>, <&cru SCLK_EMMC>;
 		clock-names = "biu", "ciu";
 		fifo-depth = <0x100>;
-- 
1.8.3.2

[PATCH] ARM: dts: rockchip: set dw_mmc max-freq 150Mhz

[Doug Anderson]

Addy,

On Wed, Dec 3, 2014 at 6:49 PM, Addy Ke <addy.ke@rock-chips.com> wrote:
> All of mmc controllers include SDMMC, SDIO0, SDIO1, and EMMC on RK3288
> are limited to 150Mhz. It was mainly caused by two reasons:
> - RK3288's IO pad(except DDR IO pad) is generic, which can only support
>   the max of 150Mhz.
> - Mmc controller was designed at 150Mhz, and the pressure test by IC team
>   was based on this freequency point.
>
> Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
> ---
>  arch/arm/boot/dts/rk3288.dtsi | 4 ++++
>  1 file changed, 4 insertions(+)

Your explanation is reasonable.  The 150MHz rate is also listed in the
latest datasheet.  It's unfortunate that we won't get full speed of
SDR104 or hs200 on this SoC, but correctness certainly outweighs
performance.

Reviewed-by: Doug Anderson <dianders@chromium.org>

I have tested that this prevents the speed from going above 150MHz on
rk3288-pinky on SD Cards, so:

Tested-by: Doug Anderson <dianders@chromium.org>

-Doug

[PATCH] ARM: dts: rockchip: set dw_mmc max-freq 150Mhz

[Heiko Stübner]

Am Donnerstag, 4. Dezember 2014, 10:49:35 schrieb Addy Ke:
> All of mmc controllers include SDMMC, SDIO0, SDIO1, and EMMC on RK3288
> are limited to 150Mhz. It was mainly caused by two reasons:
> - RK3288's IO pad(except DDR IO pad) is generic, which can only support
>   the max of 150Mhz.
> - Mmc controller was designed at 150Mhz, and the pressure test by IC team
>   was based on this freequency point.
> 
> Signed-off-by: Addy Ke <addy.ke@rock-chips.com>

applied to my wip dts branch for 3.20 (on github)


Thanks
Heiko