linux-kernel - [PATCH 2/2] ARM: dts: dra7x: Support QSPI MODE-0 operation at 64MHz

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Message-ID: <1460629101-24309-3-git-send-email-vigneshr@ti.com>
Date:	Thu, 14 Apr 2016 15:48:21 +0530
From:	Vignesh R <vigneshr@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Rob Herring <robh+dt@...nel.org>, Vignesh R <vigneshr@...com>,
	<nsekhar@...com>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH 2/2] ARM: dts: dra7x: Support QSPI MODE-0 operation at 64MHz

According to Data Manual(SPRS915P) of AM57x, TI QSPI controller on
DRA74(rev 1.1+)/DRA72 EVM can support up to 64MHz in MODE-0, whereas
MODE-3 is limited to 48MHz. Hence, switch to MODE-0 for better
throughput.

Signed-off-by: Vignesh R <vigneshr@...com>
---
 Documentation/devicetree/bindings/spi/ti_qspi.txt | 7 +++++++
 arch/arm/boot/dts/dra7-evm.dts                    | 6 ++----
 arch/arm/boot/dts/dra72-evm.dts                   | 6 ++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/ti_qspi.txt b/Documentation/devicetree/bindings/spi/ti_qspi.txt
index cc8304aa64ac..50b14f6b53a3 100644
--- a/Documentation/devicetree/bindings/spi/ti_qspi.txt
+++ b/Documentation/devicetree/bindings/spi/ti_qspi.txt
@@ -19,6 +19,13 @@ Optional properties:
 - syscon-chipselects: Handle to system control region contains QSPI
 		      chipselect register and offset of that register.
 
+NOTE: TI QSPI controller requires different pinmux and IODelay
+paramaters for Mode-0 and Mode-3 operations, which needs to be set up by
+the bootloader (U-Boot). Default configuration only supports Mode-0
+operation. Hence, "spi-cpol" and "spi-cpha" DT properties cannot be
+specified in the slave nodes of TI QSPI controller without appropriate
+modification to bootloader.
+
 Example:
 
 For am4372:
diff --git a/arch/arm/boot/dts/dra7-evm.dts b/arch/arm/boot/dts/dra7-evm.dts
index 47d0745a08ad..507a8ec0a268 100644
--- a/arch/arm/boot/dts/dra7-evm.dts
+++ b/arch/arm/boot/dts/dra7-evm.dts
@@ -664,15 +664,13 @@
 &qspi {
 	status = "okay";
 
-	spi-max-frequency = <48000000>;
+	spi-max-frequency = <64000000>;
 	m25p80@0 {
 		compatible = "s25fl256s1";
-		spi-max-frequency = <48000000>;
+		spi-max-frequency = <64000000>;
 		reg = <0>;
 		spi-tx-bus-width = <1>;
 		spi-rx-bus-width = <4>;
-		spi-cpol;
-		spi-cpha;
 		#address-cells = <1>;
 		#size-cells = <1>;
 
diff --git a/arch/arm/boot/dts/dra72-evm.dts b/arch/arm/boot/dts/dra72-evm.dts
index 479b74e1641e..46e1b72866f5 100644
--- a/arch/arm/boot/dts/dra72-evm.dts
+++ b/arch/arm/boot/dts/dra72-evm.dts
@@ -704,15 +704,13 @@
 &qspi {
 	status = "okay";
 
-	spi-max-frequency = <48000000>;
+	spi-max-frequency = <64000000>;
 	m25p80@0 {
 		compatible = "s25fl256s1";
-		spi-max-frequency = <48000000>;
+		spi-max-frequency = <64000000>;
 		reg = <0>;
 		spi-tx-bus-width = <1>;
 		spi-rx-bus-width = <4>;
-		spi-cpol;
-		spi-cpha;
 		#address-cells = <1>;
 		#size-cells = <1>;
 
-- 
2.8.1