linux-kernel - [PATCH 1/4] dmaengine: fsl-edma: fix eDMAv4 channel allocation issue

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Message-Id: <20231114154824.3617255-2-Frank.Li@nxp.com>
Date:   Tue, 14 Nov 2023 10:48:21 -0500
From:   Frank Li <Frank.Li@....com>
To:     krzysztof.kozlowski@...aro.org, shawnguo@...nel.org,
        festevam@...x.de
Cc:     Frank.li@....com, devicetree@...r.kernel.org,
        dmaengine@...r.kernel.org, imx@...ts.linux.dev, joy.zou@....com,
        krzysztof.kozlowski+dt@...aro.org, linux-kernel@...r.kernel.org,
        peng.fan@....com, robh+dt@...nel.org, shenwei.wang@....com,
        vkoul@...nel.org
Subject: [PATCH 1/4] dmaengine: fsl-edma: fix eDMAv4 channel allocation issue

The eDMAv4 channel mux has a limitation where certain requests must use
even channels, while others must use odd numbers.

Add two flags (ARGS_EVEN_CH and ARGS_ODD_CH) to reflect this limitation.
The device tree source (dts) files need to be updated accordingly.

This issue was identified by the following commit:
commit a725990557e7 ("arm64: dts: imx93: Fix the dmas entries order")

Reverting channel orders triggered this problem.

Fixes: 72f5801a4e2b ("dmaengine: fsl-edma: integrate v3 support")
Signed-off-by: Frank Li <Frank.Li@....com>
---
 drivers/dma/fsl-edma-main.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/dma/fsl-edma-main.c b/drivers/dma/fsl-edma-main.c
index 4635e16d7705e..3ee08f390f810 100644
--- a/drivers/dma/fsl-edma-main.c
+++ b/drivers/dma/fsl-edma-main.c
@@ -24,6 +24,8 @@
 #define ARGS_RX                         BIT(0)
 #define ARGS_REMOTE                     BIT(1)
 #define ARGS_MULTI_FIFO                 BIT(2)
+#define ARGS_EVEN_CH                    BIT(3)
+#define ARGS_ODD_CH                     BIT(4)
 
 static void fsl_edma_synchronize(struct dma_chan *chan)
 {
@@ -157,6 +159,12 @@ static struct dma_chan *fsl_edma3_xlate(struct of_phandle_args *dma_spec,
 		fsl_chan->is_remote = dma_spec->args[2] & ARGS_REMOTE;
 		fsl_chan->is_multi_fifo = dma_spec->args[2] & ARGS_MULTI_FIFO;
 
+		if ((dma_spec->args[2] & ARGS_EVEN_CH) && (i & 0x1))
+			continue;
+
+		if ((dma_spec->args[2] & ARGS_ODD_CH) && !(i & 0x1))
+			continue;
+
 		if (!b_chmux && i == dma_spec->args[0]) {
 			chan = dma_get_slave_channel(chan);
 			chan->device->privatecnt++;
-- 
2.34.1