diff mbox series

[v3,4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma

Message ID 20190322113456.16324-4-christoph.muellner@theobroma-systems.com (mailing list archive)
State New, archived
Headers show
Series [v3,1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS. | expand

Commit Message

Christoph Muellner March 22, 2019, 11:34 a.m. UTC 
The RK3399-Q7 (Puma) requires 33 Ohm drive strength to ensure signal
integrity at HS-400 (200MHz clock, DDR signalling).

A repeated EMC testing run validates that this increase does not
negatively impact EMC compliance (emissions have ample distance to
the regulatory limits).

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 0130b9f98c9d..4f75bb6b2f14 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -146,6 +146,7 @@ 
 
 &emmc_phy {
 	status = "okay";
+	drive-impedance-ohm = <33>;
 };
 
 &gmac {