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From:   Nishanth Menon <nm@ti.com>
To:     Roger Quadros <rogerq@ti.com>, Keerthy <j-keerthy@ti.com>,
        Jyri Sarha <jsarha@ti.com>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        Lokesh Vutla <lokeshvutla@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        Tony Lindgren <tony@atomide.com>, Tero Kristo <t-kristo@ti.com>
CC:     <linux-arm-kernel@lists.infradead.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Nishanth Menon <nm@ti.com>
Subject: [PATCH V2 2/5] arm64: dts: ti: k3-j721e*: Cleanup disabled nodes at SoC dtsi level
Date:   Wed, 11 Nov 2020 19:49:26 -0600
Message-ID: <20201112014929.25227-3-nm@ti.com>
In-Reply-To: <20201112014929.25227-1-nm@ti.com>
References: <20201112014929.25227-1-nm@ti.com>
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The device tree standard states that when the status property is
not present under a node, the okay value is assumed. There are many
reasons for doing the same, the number of strings in the device
tree, default power management functionality, etc. are a few of the
reasons.

In general, after a few rounds of discussions [1] there are few
options one could take when dealing with SoC dtsi and board dts

a. SoC dtsi provide nodes as a super-set default (aka enabled) state and
   to prevent messy board files, when more boards are added per SoC, we
   optimize and disable commonly un-used nodes in board-common.dtsi
b. SoC dtsi disables all hardware dependent nodes by default and board
   dts files enable nodes based on a need basis.
c. Subjectively pick and choose which nodes we will disable by default
   in SoC dtsi and over the years we can optimize things and change
   default state depending on the need.

While there are pros and cons on each of these approaches, the right
thing to do will be to stick with device tree default standards and
work within those established rules. So, we choose to go with option
(a).

Lets cleanup defaults of j721e SoC dtsi before this gets more harder
to cleanup later on and new SoCs are added.

The only functional difference between the dtb generated is
status='okay' is no longer necessary for mcasp10 and depends on the
default state.

NOTE: There is a known risk of omission that new board dts developers
might miss reviewing both the board schematics in addition to all the
DT nodes of the SoC when setting appropriate nodes status to disable
or reserved in the board dts. This can expose issues in drivers that
may not anticipate an incomplete node (example: missing appropriate
board properties) being in an "okay" state. These cases are considered
bugs and need to be fixed in the drivers as and when identified.

[1] https://lore.kernel.org/linux-arm-kernel/20201027130701.GE5639@atomide.com/

Fixes: 1c4d35265fb2 ("arm64: dts: ti: k3-j721e-main: Add McASP nodes")
Fixes: 76921f15acc0 ("arm64: dts: ti: k3-j721e-main: Add DSS node")
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
---
Changes since v1:
- commit message update

V1: https://lore.kernel.org/linux-arm-kernel/20201104224356.18040-3-nm@ti.com/
 .../dts/ti/k3-j721e-common-proc-board.dts     | 48 ++++++++++++++++++-
 arch/arm64/boot/dts/ti/k3-j721e-main.dtsi     | 26 ----------
 2 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/arch/arm64/boot/dts/ti/k3-j721e-common-proc-board.dts b/arch/arm64/boot/dts/ti/k3-j721e-common-proc-board.dts
index 52e121155563..9416528caa8a 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-common-proc-board.dts
+++ b/arch/arm64/boot/dts/ti/k3-j721e-common-proc-board.dts
@@ -540,6 +540,46 @@ &dss {
 				 <&k3_clks 152 18>;	/* PLL23_HSDIV0 */
 };
 
+&mcasp0 {
+	status = "disabled";
+};
+
+&mcasp1 {
+	status = "disabled";
+};
+
+&mcasp2 {
+	status = "disabled";
+};
+
+&mcasp3 {
+	status = "disabled";
+};
+
+&mcasp4 {
+	status = "disabled";
+};
+
+&mcasp5 {
+	status = "disabled";
+};
+
+&mcasp6 {
+	status = "disabled";
+};
+
+&mcasp7 {
+	status = "disabled";
+};
+
+&mcasp8 {
+	status = "disabled";
+};
+
+&mcasp9 {
+	status = "disabled";
+};
+
 &mcasp10 {
 	#sound-dai-cells = <0>;
 
@@ -556,8 +596,10 @@ &mcasp10 {
 	>;
 	tx-num-evt = <0>;
 	rx-num-evt = <0>;
+};
 
-	status = "okay";
+&mcasp11 {
+	status = "disabled";
 };
 
 &serdes0 {
@@ -639,3 +681,7 @@ &pcie3_rc {
 &pcie3_ep {
 	status = "disabled";
 };
+
+&dss {
+	status = "disabled";
+};
diff --git a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
index e2a96b2c423c..b54332d6fdc5 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-j721e-main.dtsi
@@ -1327,8 +1327,6 @@ dss: dss@04a00000 {
 				  "common_s1",
 				  "common_s2";
 
-		status = "disabled";
-
 		dss_ports: ports {
 			#address-cells = <1>;
 			#size-cells = <0>;
@@ -1350,8 +1348,6 @@ mcasp0: mcasp@2b00000 {
 		clocks = <&k3_clks 174 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 174 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp1: mcasp@2b10000 {
@@ -1369,8 +1365,6 @@ mcasp1: mcasp@2b10000 {
 		clocks = <&k3_clks 175 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 175 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp2: mcasp@2b20000 {
@@ -1388,8 +1382,6 @@ mcasp2: mcasp@2b20000 {
 		clocks = <&k3_clks 176 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 176 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp3: mcasp@2b30000 {
@@ -1407,8 +1399,6 @@ mcasp3: mcasp@2b30000 {
 		clocks = <&k3_clks 177 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 177 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp4: mcasp@2b40000 {
@@ -1426,8 +1416,6 @@ mcasp4: mcasp@2b40000 {
 		clocks = <&k3_clks 178 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 178 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp5: mcasp@2b50000 {
@@ -1445,8 +1433,6 @@ mcasp5: mcasp@2b50000 {
 		clocks = <&k3_clks 179 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 179 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp6: mcasp@2b60000 {
@@ -1464,8 +1450,6 @@ mcasp6: mcasp@2b60000 {
 		clocks = <&k3_clks 180 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 180 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp7: mcasp@2b70000 {
@@ -1483,8 +1467,6 @@ mcasp7: mcasp@2b70000 {
 		clocks = <&k3_clks 181 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 181 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp8: mcasp@2b80000 {
@@ -1502,8 +1484,6 @@ mcasp8: mcasp@2b80000 {
 		clocks = <&k3_clks 182 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 182 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp9: mcasp@2b90000 {
@@ -1521,8 +1501,6 @@ mcasp9: mcasp@2b90000 {
 		clocks = <&k3_clks 183 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 183 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp10: mcasp@2ba0000 {
@@ -1540,8 +1518,6 @@ mcasp10: mcasp@2ba0000 {
 		clocks = <&k3_clks 184 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 184 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	mcasp11: mcasp@2bb0000 {
@@ -1559,8 +1535,6 @@ mcasp11: mcasp@2bb0000 {
 		clocks = <&k3_clks 185 1>;
 		clock-names = "fck";
 		power-domains = <&k3_pds 185 TI_SCI_PD_EXCLUSIVE>;
-
-		status = "disabled";
 	};
 
 	watchdog0: watchdog@2200000 {
-- 
2.29.2