From 3f4b82167a3b1f4ddb33d890f758a042ef4ceef1 Mon Sep 17 00:00:00 2001
From: Frank Li <Frank.Li@nxp.com>
Date: Wed, 23 Aug 2023 14:26:35 -0400
Subject: [PATCH] dmaengine: fsl-edma: fix edma4 channel enable failure on
second attempt
When attempting to start DMA for the second time using
fsl_edma3_enable_request(), channel never start.
CHn_MUX must have a unique value when selecting a peripheral slot in the
channel mux configuration. The only value that may overlap is source 0.
If there is an attempt to write a mux configuration value that is already
consumed by another channel, a mux configuration of 0 (SRC = 0) will be
written.
Check CHn_MUX before writing in fsl_edma3_enable_request().
Fixes: 72f5801a4e2b ("dmaengine: fsl-edma: integrate v3 support")
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20230823182635.2618118-1-Frank.Li@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
drivers/dma/fsl-edma-common.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/fsl-edma-common.c b/drivers/dma/fsl-edma-common.c
index 50203b82f9f55..6a3abe5b17908 100644
--- a/drivers/dma/fsl-edma-common.c
+++ b/drivers/dma/fsl-edma-common.c
@@ -92,8 +92,14 @@ static void fsl_edma3_enable_request(struct fsl_edma_chan *fsl_chan)
edma_writel_chreg(fsl_chan, val, ch_sbr);
- if (flags & FSL_EDMA_DRV_HAS_CHMUX)
- edma_writel_chreg(fsl_chan, fsl_chan->srcid, ch_mux);
+ if (flags & FSL_EDMA_DRV_HAS_CHMUX) {
+ /*
+ * ch_mux: With the exception of 0, attempts to write a value
+ * already in use will be forced to 0.
+ */
+ if (!edma_readl_chreg(fsl_chan, ch_mux))
+ edma_writel_chreg(fsl_chan, fsl_chan->srcid, ch_mux);
+ }
val = edma_readl_chreg(fsl_chan, ch_csr);
val |= EDMA_V3_CH_CSR_ERQ;