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From: Christoph Muellner <christoph.muellner@theobroma-systems.com>
To: robh+dt@kernel.org, mark.rutland@arm.com, heiko@sntech.de,
	shawn.lin@rock-chips.com
Cc: Christoph Muellner <christoph.muellner@theobroma-systems.com>,
	Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Douglas Anderson <dianders@chromium.org>,
	Brian Norris <briannorris@chromium.org>,
	Klaus Goger <klaus.goger@theobroma-systems.com>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Matthias Brugger <mbrugger@suse.com>,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	Randy Li <ayaka@soulik.info>, Tony Xie <tony.xie@rock-chips.com>,
	Vicente Bergas <vicencb@gmail.com>,
	Ezequiel Garcia <ezequiel@collabora.com>,
	Lin Huang <hl@rock-chips.com>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org
Subject: [PATCH v2 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma
Date: Thu,  7 Mar 2019 09:41:56 +0100	[thread overview]
Message-ID: <20190307084159.25236-4-christoph.muellner@theobroma-systems.com> (raw)
In-Reply-To: <20190307084159.25236-1-christoph.muellner@theobroma-systems.com>

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 --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 {
-- 
2.11.0


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Muellner <christoph.muellner@theobroma-systems.com>
To: robh+dt@kernel.org, mark.rutland@arm.com, heiko@sntech.de,
	shawn.lin@rock-chips.com
Cc: Christoph Muellner <christoph.muellner@theobroma-systems.com>,
	Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	Douglas Anderson <dianders@chromium.org>,
	Brian Norris <briannorris@chromium.org>,
	Klaus Goger <klaus.goger@theobroma-systems.com>,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Matthias Brugger <mbrugger@suse.com>,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	Randy Li <ayaka@soulik.info>, Tony Xie <tony.xie@rock-chips.com>,
	Vicente Bergas <vicencb@gmail.com>,
	Ezequiel Garcia <ezequiel@collabora.com>,
	Lin Huang <hl@rock-chips.com>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.o
Subject: [PATCH v2 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma
Date: Thu,  7 Mar 2019 09:41:56 +0100	[thread overview]
Message-ID: <20190307084159.25236-4-christoph.muellner@theobroma-systems.com> (raw)
In-Reply-To: <20190307084159.25236-1-christoph.muellner@theobroma-systems.com>

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 --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 {
-- 
2.11.0

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Muellner <christoph.muellner@theobroma-systems.com>
To: robh+dt@kernel.org, mark.rutland@arm.com, heiko@sntech.de,
	shawn.lin@rock-chips.com
Cc: devicetree@vger.kernel.org, Matthias Brugger <mbrugger@suse.com>,
	Lin Huang <hl@rock-chips.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Brian Norris <briannorris@chromium.org>,
	Douglas Anderson <dianders@chromium.org>,
	Vicente Bergas <vicencb@gmail.com>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	linux-rockchip@lists.infradead.org,
	Jeffy Chen <jeffy.chen@rock-chips.com>,
	Tony Xie <tony.xie@rock-chips.com>,
	Klaus Goger <klaus.goger@theobroma-systems.com>,
	linux-arm-kernel@lists.infradead.org,
	Enric Balletbo i Serra <enric.balletbo@collabora.com>,
	Randy Li <ayaka@soulik.info>,
	Philipp Tomsich <philipp.tomsich@theobroma-systems.com>,
	Ezequiel Garcia <ezequiel@collabora.com>,
	linux-kernel@vger.kernel.org,
	Christoph Muellner <christoph.muellner@theobroma-systems.com>
Subject: [PATCH v2 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma
Date: Thu,  7 Mar 2019 09:41:56 +0100	[thread overview]
Message-ID: <20190307084159.25236-4-christoph.muellner@theobroma-systems.com> (raw)
In-Reply-To: <20190307084159.25236-1-christoph.muellner@theobroma-systems.com>

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 --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 {
-- 
2.11.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-03-07  8:43 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-07  8:41 [PATCH v2 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS Christoph Muellner
2019-03-07  8:41 ` Christoph Muellner
2019-03-07  8:41 ` Christoph Muellner
2019-03-07  8:41 ` [PATCH v2 2/4] dt-bindings: phy: Add a new property drive-impedance-ohm for RK's emmc PHY Christoph Muellner
2019-03-07  8:41   ` Christoph Muellner
2019-03-12 12:52   ` Heiko Stuebner
2019-03-12 12:52     ` Heiko Stuebner
2019-03-12 13:01     ` Christoph Müllner
2019-03-12 13:01       ` Christoph Müllner
2019-03-07  8:41 ` [PATCH v2 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy Christoph Muellner
2019-03-07  8:41   ` Christoph Muellner
2019-03-07  8:41   ` Christoph Muellner
2019-03-07  8:41 ` Christoph Muellner [this message]
2019-03-07  8:41   ` [PATCH v2 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma Christoph Muellner
2019-03-07  8:41   ` Christoph Muellner
2019-03-12 13:07 ` [PATCH v2 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS Heiko Stuebner
2019-03-12 13:07   ` Heiko Stuebner
2019-03-12 13:07   ` Heiko Stuebner

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