linux-kernel - [PATCH 04/33] Revert "arm64: dts: ti: k3-j721e-beagleboneai64: Fix reversed C6x carveout locations"

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Message-ID: <20250814223839.3256046-5-b-padhi@ti.com>
Date: Fri, 15 Aug 2025 04:08:10 +0530
From: Beleswar Padhi <b-padhi@...com>
To: <nm@...com>, <vigneshr@...com>, <kristo@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>
CC: <afd@...com>, <u-kumar1@...com>, <hnagalla@...com>, <jm@...com>,
        <b-padhi@...com>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH 04/33] Revert "arm64: dts: ti: k3-j721e-beagleboneai64: Fix reversed C6x carveout locations"

This reverts commit 1a314099b7559690fe23cdf3300dfff6e830ecb1.

The C6x carveouts are reversed intentionally. This is due to the
requirement to keep the DMA memory region as non-cached, however the
minimum granular cache region for C6x is 16MB. So, C66x_0 marks the
entire C66x_1 16MB memory carveouts as non-cached, and uses the DMA
memory region of C66x_1 as its own, and vice-versa.

This was also called out in the original commit which introduced these
reversed carveouts:
	"The minimum granularity on the Cache settings on C66x DSP
	cores is 16MB, so the DMA memory regions are chosen such that
	they are in separate 16MB regions for each DSP, while reserving
	a total of 16 MB for each DSP and not changing the overall DSP
        remoteproc carveouts."

Fixes: 1a314099b755 ("arm64: dts: ti: k3-j721e-beagleboneai64: Fix reversed C6x carveout locations")
Signed-off-by: Beleswar Padhi <b-padhi@...com>
---
 arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts b/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
index fb899c99753e..6e7f321f3e8a 100644
--- a/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
+++ b/arch/arm64/boot/dts/ti/k3-j721e-beagleboneai64.dts
@@ -123,7 +123,8 @@ main_r5fss1_core1_memory_region: r5f-memory@...00000 {
 			no-map;
 		};
 
-		c66_0_dma_memory_region: c66-dma-memory@...00000 {
+		/* Carveout locations are flipped due to caching */
+		c66_1_dma_memory_region: c66-dma-memory@...00000 {
 			compatible = "shared-dma-pool";
 			reg = <0x00 0xa6000000 0x00 0x100000>;
 			no-map;
@@ -135,7 +136,8 @@ c66_0_memory_region: c66-memory@...00000 {
 			no-map;
 		};
 
-		c66_1_dma_memory_region: c66-dma-memory@...00000 {
+		/* Carveout locations are flipped due to caching */
+		c66_0_dma_memory_region: c66-dma-memory@...00000 {
 			compatible = "shared-dma-pool";
 			reg = <0x00 0xa7000000 0x00 0x100000>;
 			no-map;
-- 
2.34.1