dmaengine: fsl-edma: fix channel parameter config for fixed channel requests

Configure only the requested channel when a fixed channel is specified
to avoid modifying other channels unintentionally.

Fix parameter configuration when a fixed DMA channel is requested on
i.MX9 AON domain and i.MX8QM/QXP/DXL platforms. When a client requests
a fixed channel (e.g., channel 6), the driver traverses channels 0-5
and may unintentionally modify their configuration if they are unused.

This leads to issues such as setting the `is_multi_fifo` flag unexpectedly,
causing memcpy tests to fail when using the dmatest tool.

Only affect edma memcpy test when the channel is fixed.

Fixes: 72f5801 ("dmaengine: fsl-edma: integrate v3 support")
Signed-off-by: Joy Zou <joy.zou@nxp.com>
Cc: stable@vger.kernel.org
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250917-b4-edma-chanconf-v1-1-886486e02e91@nxp.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: 1991Joyzou

drivers/dma/fsl-edma-main.c

@@ -317,28 +317,24 @@ static struct dma_chan *fsl_edma3_xlate(struct of_phandle_args *dma_spec,
 			return NULL;
 		i = fsl_chan - fsl_edma->chans;
 
-		fsl_chan->priority = dma_spec->args[1];
-		fsl_chan->is_rxchan = dma_spec->args[2] & FSL_EDMA_RX;
-		fsl_chan->is_remote = dma_spec->args[2] & FSL_EDMA_REMOTE;
-		fsl_chan->is_multi_fifo = dma_spec->args[2] & FSL_EDMA_MULTI_FIFO;
+		if (!b_chmux && i != dma_spec->args[0])
+			continue;
 
 		if ((dma_spec->args[2] & FSL_EDMA_EVEN_CH) && (i & 0x1))
 			continue;
 
 		if ((dma_spec->args[2] & FSL_EDMA_ODD_CH) && !(i & 0x1))
 			continue;
 
-		if (!b_chmux && i == dma_spec->args[0]) {
-			chan = dma_get_slave_channel(chan);
-			chan->device->privatecnt++;
-			return chan;
-		} else if (b_chmux && !fsl_chan->srcid) {
-			/* if controller support channel mux, choose a free channel */
-			chan = dma_get_slave_channel(chan);
-			chan->device->privatecnt++;
-			fsl_chan->srcid = dma_spec->args[0];
-			return chan;
-		}
+		fsl_chan->srcid = dma_spec->args[0];
+		fsl_chan->priority = dma_spec->args[1];
+		fsl_chan->is_rxchan = dma_spec->args[2] & FSL_EDMA_RX;
+		fsl_chan->is_remote = dma_spec->args[2] & FSL_EDMA_REMOTE;
+		fsl_chan->is_multi_fifo = dma_spec->args[2] & FSL_EDMA_MULTI_FIFO;
+
+		chan = dma_get_slave_channel(chan);
+		chan->device->privatecnt++;
+		return chan;
 	}
 	return NULL;
 }