This is a note to let you know that I've just added the patch titled
arm64: dts: rockchip: fix rk3399-puma eMMC HS400 signal integrity
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm64-dts-rockchip-fix-rk3399-puma-emmc-hs400-signal.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 222f6af9cc36df8a44080885e337b0f4799e548f
Author: Jakob Unterwurzacher <jakob.unterwurzacher@xxxxxxxxxxxxxxxxxxxxx>
Date: Wed Jan 19 14:49:48 2022 +0100
arm64: dts: rockchip: fix rk3399-puma eMMC HS400 signal integrity
[ 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@xxxxxxxxx>
Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220119134948.1444965-1-quentin.schulz@xxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 45b86933c6ea..390b86ec6538 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -467,6 +467,12 @@
};
&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;
