From: Jakob Unterwurzacher jakob.unterwurzacher@theobroma-systems.com
[ Upstream commit 62966cbdda8a92f82d966a45aa671e788b2006f7 ]
There are signal integrity issues running the eMMC at 200MHz on Puma RK3399-Q7.
Similar to the work-around found for RK3399 Gru boards, lowering the frequency to 100MHz made the eMMC much more stable, so let's lower the frequency to 100MHz.
It might be possible to run at 150MHz as on RK3399 Gru boards but only 100MHz was extensively tested.
Cc: Quentin Schulz foss+kernel@0leil.net Signed-off-by: Jakob Unterwurzacher jakob.unterwurzacher@theobroma-systems.com Signed-off-by: Quentin Schulz quentin.schulz@theobroma-systems.com Link: https://lore.kernel.org/r/20220119134948.1444965-1-quentin.schulz@theobroma-... Signed-off-by: Heiko Stuebner heiko@sntech.de Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi index 002ece51c3ba..08fa00364b42 100644 --- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi @@ -439,6 +439,12 @@ usb3_id: usb3-id { };
&sdhci { + /* + * Signal integrity isn't great at 200MHz but 100MHz has proven stable + * enough. + */ + max-frequency = <100000000>; + bus-width = <8>; mmc-hs400-1_8v; mmc-hs400-enhanced-strobe;