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arm64: dts: rockchip: fix rk3399-puma eMMC HS400 signal integrity 

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>
This commit is contained in:
Jakob Unterwurzacher 2022-01-19 14:49:48 +01:00 committed by Heiko Stuebner
parent ad02776cf8
commit 62966cbdda
1 changed files with 6 additions and 0 deletions
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6
arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
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@ -439,6 +439,12 @@
};
&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;