Hi,
we observed a regression on our atmel platforms on branch 5.4.Y from version 5.4.174. uarts are no longer functional if DMA is enabled.
the following patch Commit e6af9b05bec63cd4d1de2a33968cd0be2a91282a dmaengine: at_xdmac: Start transfer for cyclic channels in issue_pending Link: https://lore.kernel.org/r/20211215110115.191749-3-tudor.ambarus@microchip.co... has not been backported but is needed if the patch Commit 4f4b9b5895614eb2e2b5f4cab7858f44bd113e1b tty: serial: atmel: Call dma_async_issue_pending() Link: https://lore.kernel.org/r/20211125090028.786832-4-tudor.ambarus@microchip.co... is applied.
enclosed commit fix this issue and work for me.
Best regards, Mickael GARDET
From 9877f93c066be8c2f4e33a6edd4dfa3d6d6974d9 Mon Sep 17 00:00:00 2001 From: Tudor Ambarus tudor.ambarus@microchip.com Date: Wed, 15 Dec 2021 13:01:05 +0200 Subject: [PATCH] dmaengine: at_xdmac: Start transfer for cyclic channels in issue_pending
commit e6af9b05bec63cd4d1de2a33968cd0be2a91282a upstream.
Cyclic channels must too call issue_pending in order to start a transfer. Start the transfer in issue_pending regardless of the type of channel. This wrongly worked before, because in the past the transfer was started at tx_submit level when only a desc in the transfer list.
Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver") Change-Id: If1bf3e13329cebb9904ae40620f6cf2b7f06fe9f Signed-off-by: Tudor Ambarus tudor.ambarus@microchip.com Link: https://lore.kernel.org/r/20211215110115.191749-3-tudor.ambarus@microchip.co... Signed-off-by: Vinod Koul vkoul@kernel.org --- drivers/dma/at_xdmac.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c index f63d141481a3..9aae6b3da356 100644 --- a/drivers/dma/at_xdmac.c +++ b/drivers/dma/at_xdmac.c @@ -1726,11 +1726,13 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id) static void at_xdmac_issue_pending(struct dma_chan *chan) { struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan); + unsigned long flags;
dev_dbg(chan2dev(&atchan->chan), "%s\n", __func__);
- if (!at_xdmac_chan_is_cyclic(atchan)) - at_xdmac_advance_work(atchan); + spin_lock_irqsave(&atchan->lock, flags); + at_xdmac_advance_work(atchan); + spin_unlock_irqrestore(&atchan->lock, flags);
return; }
base-commit: 7b3eb66d0daf61e91cccdb2fe5d271ae5adc5a76