| From 027946989b7ef6267df49221091869d7e0cf8feb Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Wed, 19 Jan 2022 14:49:48 +0100 |
| Subject: arm64: dts: rockchip: fix rk3399-puma eMMC HS400 signal integrity |
| |
| 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-systems.com |
| 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 b155f657292b..ce1320e4c106 100644 |
| --- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi |
| +++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi |
| @@ -468,6 +468,12 @@ |
| }; |
| |
| &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; |
| -- |
| 2.34.1 |
| |
