[RFC PATCH 1/3] arm: mvebu: add new dts file for old variant of Openblocks AX3-4

Hi Jason,

I have just send a new series which I hope will supersede this one.
However I will answer on some points:

On 01/01/2014 22:41, Jason Cooper wrote:

Gregory,

Sorry, but we seem to have a fundamental mis-understanding here.  First,
whatever we end up deciding for the compatible strings needs to be
documented.  Which seems to have not made it into this series.

Second, I'm having trouble explaining this (in my head), so I'm adding
the DT ml so hopefully someone there can chime in.

AFAICT, the marvell,mv78230-i2c compatible string, added in v3.12, refers
to the IP block on the A0 revision of the SoC.  Since we have set that,

Actually in v3.12 the marvell,mv78230-i2c refer to the B0 revision as I
only worked on it on board using this revision. That's why I proposed
to introduced the marvell,mv78230-a0-i2c compatible string. My concerns was
to not break the existing behavior.

Currently with the marvell,mv78230-i2c compatible string the kernel use
offload on B0 version and hang on A0 version.

If we introduce the marvell,mv78230-a0-i2c compatible string, then the new
kernel with the same dtb will have the same behavior. People using the A0
version are aware that there is a problem (the kernel hang) so they will
be willing to switch to marvell,mv78230-a0-i2c and to change their dtb.

If we introduce the marvell,mv78230-b0-i2c compatible string, then the new
kernel with the same dtb will have different behavior. People using the A0
will have a booting kernel, but I fear that people using B0 revision won't
be aware of the regression.

Gregory

we've discovered that the A0 revision has an errata where offloading
doesn't work.  The B0 revision of the SoC has fixed offloading for i2c.

In my mind, this means that we should create a fix for the driver to
disable offloading unless it can determine it's running B0 or newer.
This is easy once we nail down the compatible strings.

The second thing we need to do is update the binding documentation so
that the devicetree can describe the hardware accurately.  I think we
should keep 'marvell,mv78230-i2c' as it is (the driver fix mentioned
above will disable offloading), and add a new compatible
string, 'marvell,mv78230-b0-i2c'.  The driver can then be updated to
enable offloading when it sees this compatible string, or it can
determine the SoC revision itself (via mach code).

Third, we need to be able to differentiate between the two shipped
AX3-4 boards by openblocks.  I think this should follow the same pattern
we decide for the i2c compatible string.  So, if we go with my proposal,
we would have plathome,openblocks-ax3-4 and
plathome,openblocks-ax3-4-b0.

Basically, I'm really uneasy about dropping marvell,mv78230-i2c and
essentially re-defining it to marvell,mv78230-a0-i2c.  It feels like
it's breaking backwards compatibility.  But I'm having trouble clearly
describing how Gregory's proposed change exactly does break backwards
compatibility.  Can a DT maintainer explain it more clearly than I?

thx,

Jason.

PS- Well, this ended up being a toppost.  Oops.  Sorry.

On Tue, Dec 31, 2013 at 05:44:51PM +0100, Gregory CLEMENT wrote:

quoted

The first variants of Openblocks AX3-4 used the revision A0 of the
Armada XP SoCs. These early variants have issues related to the i2c
controller which prevent to use the offload mechanism and lead to a
kernel hang during boot.

The new dts file uses the compatible string marvell,mv78230-a0-i2c for
the i2c controller, thanks to this the driver disable the offload
mechanism and the kernel no more hangs on these boards.

Signed-off-by: Gregory CLEMENT <redacted>
---
 .../arm/boot/dts/armada-xp-a0-openblocks-ax3-4.dts |  40 +++++
 .../dts/armada-xp-common-openblocks-ax3-4.dtsi     | 177 +++++++++++++++++++++
 arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts   | 164 +------------------
 3 files changed, 218 insertions(+), 163 deletions(-)
 create mode 100644 arch/arm/boot/dts/armada-xp-a0-openblocks-ax3-4.dts
 create mode 100644 arch/arm/boot/dts/armada-xp-common-openblocks-ax3-4.dtsi

diff --git a/arch/arm/boot/dts/armada-xp-a0-openblocks-ax3-4.dts b/arch/arm/boot/dts/armada-xp-a0-openblocks-ax3-4.dts
new file mode 100644
index 000000000000..b3ea65255c19
--- /dev/null
+++ b/arch/arm/boot/dts/armada-xp-a0-openblocks-ax3-4.dts

@@ -0,0 +1,40 @@
+/*
+ * Device Tree file for OpenBlocks AX3-4 board with A0 SoC
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+/dts-v1/;
+#include "armada-xp-common-openblocks-ax3-4.dtsi"
+
+/ {
+	model = "PlatHome OpenBlocks AX3-4 board (A0 SoC)";
+	compatible = "plathome,openblocks-ax3-4", "marvell,armadaxp-mv78260", "marvell,armadaxp", "marvell,armada-370-xp";
+
+	chosen {
+		bootargs = "console=ttyS0,115200 earlyprintk";
+	};
+
+	memory {
+		device_type = "memory";
+		reg = <0 0x00000000 0 0xC0000000>; /* 3 GB */
+	};
+
+	soc {
+
+		internal-regs {
+			i2c at 11000 {
+				compatible = "marvell,mv78230-a0-i2c", "marvell,mv64xxx-i2c";
+			};
+			i2c at 11100 {
+				compatible = "marvell,mv78230-a0-i2c", "marvell,mv64xxx-i2c";
+			};
+		};
+	};
+};

diff --git a/arch/arm/boot/dts/armada-xp-common-openblocks-ax3-4.dtsi b/arch/arm/boot/dts/armada-xp-common-openblocks-ax3-4.dtsi
new file mode 100644
index 000000000000..0d452b07baf5
--- /dev/null
+++ b/arch/arm/boot/dts/armada-xp-common-openblocks-ax3-4.dtsi

@@ -0,0 +1,177 @@
+/*
+ * Device Tree file for OpenBlocks AX3-4 board
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include "armada-xp-mv78260.dtsi"
+
+/ {
+	soc {
+		ranges = <MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000
+			  MBUS_ID(0x01, 0x1d) 0 0 0xfff00000 0x100000
+			  MBUS_ID(0x01, 0x2f) 0 0 0xf0000000 0x8000000>;
+
+		devbus-bootcs {
+			status = "okay";
+
+			/* Device Bus parameters are required */
+
+			/* Read parameters */
+			devbus,bus-width    = <8>;
+			devbus,turn-off-ps  = <60000>;
+			devbus,badr-skew-ps = <0>;
+			devbus,acc-first-ps = <124000>;
+			devbus,acc-next-ps  = <248000>;
+			devbus,rd-setup-ps  = <0>;
+			devbus,rd-hold-ps   = <0>;
+
+			/* Write parameters */
+			devbus,sync-enable = <0>;
+			devbus,wr-high-ps  = <60000>;
+			devbus,wr-low-ps   = <60000>;
+			devbus,ale-wr-ps   = <60000>;
+
+			/* NOR 128 MiB */
+			nor at 0 {
+				compatible = "cfi-flash";
+				reg = <0 0x8000000>;
+				bank-width = <2>;
+			};
+		};
+
+		pcie-controller {
+			status = "okay";
+			/* Internal mini-PCIe connector */
+			pcie at 1,0 {
+				/* Port 0, Lane 0 */
+				status = "okay";
+			};
+		};
+
+		internal-regs {
+			serial at 12000 {
+				clock-frequency = <250000000>;
+				status = "okay";
+			};
+			serial at 12100 {
+				clock-frequency = <250000000>;
+				status = "okay";
+			};
+			pinctrl {
+				led_pins: led-pins-0 {
+					marvell,pins = "mpp49", "mpp51", "mpp53";
+					marvell,function = "gpio";
+				};
+			};
+			leds {
+				compatible = "gpio-leds";
+				pinctrl-names = "default";
+				pinctrl-0 = <&led_pins>;
+
+				red_led {
+					label = "red_led";
+					gpios = <&gpio1 17 1>;
+					default-state = "off";
+				};
+
+				yellow_led {
+					label = "yellow_led";
+					gpios = <&gpio1 19 1>;
+					default-state = "off";
+				};
+
+				green_led {
+					label = "green_led";
+					gpios = <&gpio1 21 1>;
+					default-state = "off";
+					linux,default-trigger = "heartbeat";
+				};
+			};
+
+			gpio_keys {
+				compatible = "gpio-keys";
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				button at 1 {
+					label = "Init Button";
+					linux,code = <116>;
+					gpios = <&gpio1 28 0>;
+				};
+			};
+
+			mdio {
+				phy0: ethernet-phy at 0 {
+					reg = <0>;
+				};
+
+				phy1: ethernet-phy at 1 {
+					reg = <1>;
+				};
+
+				phy2: ethernet-phy at 2 {
+					reg = <2>;
+				};
+
+				phy3: ethernet-phy at 3 {
+					reg = <3>;
+				};
+			};
+
+			ethernet at 70000 {
+				status = "okay";
+				phy = <&phy0>;
+				phy-mode = "sgmii";
+			};
+			ethernet at 74000 {
+				status = "okay";
+				phy = <&phy1>;
+				phy-mode = "sgmii";
+			};
+			ethernet at 30000 {
+				status = "okay";
+				phy = <&phy2>;
+				phy-mode = "sgmii";
+			};
+			ethernet at 34000 {
+				status = "okay";
+				phy = <&phy3>;
+				phy-mode = "sgmii";
+			};
+			i2c at 11000 {
+				status = "okay";
+				clock-frequency = <400000>;
+			};
+			i2c at 11100 {
+				status = "okay";
+				clock-frequency = <400000>;
+
+				s35390a: s35390a at 30 {
+					compatible = "s35390a";
+					reg = <0x30>;
+				};
+			};
+			sata at a0000 {
+				nr-ports = <2>;
+				status = "okay";
+			};
+
+			/* Front side USB 0 */
+			usb at 50000 {
+				status = "okay";
+			};
+
+			/* Front side USB 1 */
+			usb at 51000 {
+				status = "okay";
+			};
+		};
+	};
+};

diff --git a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
index 5695afcc04bf..1983de77c3ff 100644
--- a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
+++ b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts

@@ -11,7 +11,7 @@
  */
 
 /dts-v1/;
-#include "armada-xp-mv78260.dtsi"
+#include "armada-xp-common-openblocks-ax3-4.dtsi"
 
 / {
 	model = "PlatHome OpenBlocks AX3-4 board";

@@ -25,166 +25,4 @@
 		device_type = "memory";
 		reg = <0 0x00000000 0 0xC0000000>; /* 3 GB */
 	};
-
-	soc {
-		ranges = <MBUS_ID(0xf0, 0x01) 0 0 0xd0000000 0x100000
-			  MBUS_ID(0x01, 0x1d) 0 0 0xfff00000 0x100000
-			  MBUS_ID(0x01, 0x2f) 0 0 0xf0000000 0x8000000>;
-
-		devbus-bootcs {
-			status = "okay";
-
-			/* Device Bus parameters are required */
-
-			/* Read parameters */
-			devbus,bus-width    = <8>;
-			devbus,turn-off-ps  = <60000>;
-			devbus,badr-skew-ps = <0>;
-			devbus,acc-first-ps = <124000>;
-			devbus,acc-next-ps  = <248000>;
-			devbus,rd-setup-ps  = <0>;
-			devbus,rd-hold-ps   = <0>;
-
-			/* Write parameters */
-			devbus,sync-enable = <0>;
-			devbus,wr-high-ps  = <60000>;
-			devbus,wr-low-ps   = <60000>;
-			devbus,ale-wr-ps   = <60000>;
-
-			/* NOR 128 MiB */
-			nor at 0 {
-				compatible = "cfi-flash";
-				reg = <0 0x8000000>;
-				bank-width = <2>;
-			};
-		};
-
-		pcie-controller {
-			status = "okay";
-			/* Internal mini-PCIe connector */
-			pcie at 1,0 {
-				/* Port 0, Lane 0 */
-				status = "okay";
-			};
-		};
-
-		internal-regs {
-			serial at 12000 {
-				clock-frequency = <250000000>;
-				status = "okay";
-			};
-			serial at 12100 {
-				clock-frequency = <250000000>;
-				status = "okay";
-			};
-			pinctrl {
-				led_pins: led-pins-0 {
-					marvell,pins = "mpp49", "mpp51", "mpp53";
-					marvell,function = "gpio";
-				};
-			};
-			leds {
-				compatible = "gpio-leds";
-				pinctrl-names = "default";
-				pinctrl-0 = <&led_pins>;
-
-				red_led {
-					label = "red_led";
-					gpios = <&gpio1 17 1>;
-					default-state = "off";
-				};
-
-				yellow_led {
-					label = "yellow_led";
-					gpios = <&gpio1 19 1>;
-					default-state = "off";
-				};
-
-				green_led {
-					label = "green_led";
-					gpios = <&gpio1 21 1>;
-					default-state = "off";
-					linux,default-trigger = "heartbeat";
-				};
-			};
-
-			gpio_keys {
-				compatible = "gpio-keys";
-				#address-cells = <1>;
-				#size-cells = <0>;
-
-				button at 1 {
-					label = "Init Button";
-					linux,code = <116>;
-					gpios = <&gpio1 28 0>;
-				};
-			};
-
-			mdio {
-				phy0: ethernet-phy at 0 {
-					reg = <0>;
-				};
-
-				phy1: ethernet-phy at 1 {
-					reg = <1>;
-				};
-
-				phy2: ethernet-phy at 2 {
-					reg = <2>;
-				};
-
-				phy3: ethernet-phy at 3 {
-					reg = <3>;
-				};
-			};
-
-			ethernet at 70000 {
-				status = "okay";
-				phy = <&phy0>;
-				phy-mode = "sgmii";
-			};
-			ethernet at 74000 {
-				status = "okay";
-				phy = <&phy1>;
-				phy-mode = "sgmii";
-			};
-			ethernet at 30000 {
-				status = "okay";
-				phy = <&phy2>;
-				phy-mode = "sgmii";
-			};
-			ethernet at 34000 {
-				status = "okay";
-				phy = <&phy3>;
-				phy-mode = "sgmii";
-			};
-			i2c at 11000 {
-				status = "okay";
-				clock-frequency = <400000>;
-			};
-			i2c at 11100 {
-				status = "okay";
-				clock-frequency = <400000>;
-
-				s35390a: s35390a at 30 {
-					compatible = "s35390a";
-					reg = <0x30>;
-				};
-			};
-			sata at a0000 {
-				nr-ports = <2>;
-				status = "okay";
-			};
-
-			/* Front side USB 0 */
-			usb at 50000 {
-				status = "okay";
-			};
-
-			/* Front side USB 1 */
-			usb at 51000 {
-				status = "okay";
-			};
-		};
-	};
 };

-- 
1.8.1.2

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com