linux-kernel - [PATCH 2/4] dmaengine: stm32-dmamux: set dmamux channel id in dma features bitfield

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Date:   Mon, 11 Jul 2022 10:47:01 +0200
From:   Amelie Delaunay <amelie.delaunay@...s.st.com>
To:     Jonathan Corbet <corbet@....net>, Vinod Koul <vkoul@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>
CC:     <linux-doc@...r.kernel.org>, <dmaengine@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Marek Vasut <marex@...x.de>,
        Amelie Delaunay <amelie.delaunay@...s.st.com>
Subject: [PATCH 2/4] dmaengine: stm32-dmamux: set dmamux channel id in dma features bitfield

STM32 DMAMUX is used with STM32 DMA1 and DMA2:
- DMAMUX channels 0 to 7 are connected to DMA1 channels 0 to 7
- DMAMUX channels 8 to 15 are connected to DMA2 channels 0 to 7

STM32 MDMA can be triggered by DMA1 and DMA2 channels transfer complete,
and the "request line number" is the DMAMUX channel id (e.g. DMA2 channel 0
triggers MDMA with request line 8).

To well configure MDMA, set DMAMUX channel id in DMA features bitfield,
so that DMA can update struct dma_slave_config peripheral_config properly.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
---
 drivers/dma/stm32-dmamux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/dma/stm32-dmamux.c b/drivers/dma/stm32-dmamux.c
index eee0c5aa5fb5..b431f9da9206 100644
--- a/drivers/dma/stm32-dmamux.c
+++ b/drivers/dma/stm32-dmamux.c
@@ -147,7 +147,7 @@ static void *stm32_dmamux_route_allocate(struct of_phandle_args *dma_spec,
 	mux->request = dma_spec->args[0];
 
 	/*  craft DMA spec */
-	dma_spec->args[3] = dma_spec->args[2];
+	dma_spec->args[3] = dma_spec->args[2] | mux->chan_id << 16;
 	dma_spec->args[2] = dma_spec->args[1];
 	dma_spec->args[1] = 0;
 	dma_spec->args[0] = mux->chan_id - min;
-- 
2.25.1