[PATCH AUTOSEL 6.6 01/10] dmaengine: apple-admac: Keep upper bits of REG_BUS_WIDTH

[Sasha Levin]

From: Hector Martin <marcan at marcan.st>

[ Upstream commit 306f5df81fcc89b462fbeb9dbe26d9a8ad7c7582 ]

For RX channels, REG_BUS_WIDTH seems to default to a value of 0xf00, and
macOS preserves the upper bits when setting the configuration in the
lower ones. If we reset the upper bits to 0, this causes framing errors
on suspend/resume (the data stream "tears" and channels get swapped
around). Keeping the upper bits untouched, like the macOS driver does,
fixes this issue.

Signed-off-by: Hector Martin <marcan at marcan.st>
Reviewed-by: Martin Povišer <povik+lin at cutebit.org>
Signed-off-by: Martin Povišer <povik+lin at cutebit.org>
Link: https://lore.kernel.org/r/20231029170704.82238-1-povik+lin@cutebit.org
Signed-off-by: Vinod Koul <vkoul at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/dma/apple-admac.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/apple-admac.c b/drivers/dma/apple-admac.c
index 3af795635c5c..356298e4dd22 100644
--- a/drivers/dma/apple-admac.c
+++ b/drivers/dma/apple-admac.c
@@ -57,6 +57,8 @@
 
 #define REG_BUS_WIDTH(ch)	(0x8040 + (ch) * 0x200)
 
+#define BUS_WIDTH_WORD_SIZE	GENMASK(3, 0)
+#define BUS_WIDTH_FRAME_SIZE	GENMASK(7, 4)
 #define BUS_WIDTH_8BIT		0x00
 #define BUS_WIDTH_16BIT		0x01
 #define BUS_WIDTH_32BIT		0x02
@@ -740,7 +742,8 @@ static int admac_device_config(struct dma_chan *chan,
 	struct admac_data *ad = adchan->host;
 	bool is_tx = admac_chan_direction(adchan->no) == DMA_MEM_TO_DEV;
 	int wordsize = 0;
-	u32 bus_width = 0;
+	u32 bus_width = readl_relaxed(ad->base + REG_BUS_WIDTH(adchan->no)) &
+		~(BUS_WIDTH_WORD_SIZE | BUS_WIDTH_FRAME_SIZE);
 
 	switch (is_tx ? config->dst_addr_width : config->src_addr_width) {
 	case DMA_SLAVE_BUSWIDTH_1_BYTE:
-- 
2.43.0