[PATCH 5.4 305/320] dmaengine: at_xdmac: Dont start transactions at tx_submit level

Greg Kroah-Hartman
2022-01-24T20:24:36Z

From: Tudor Ambarus <tudor.ambarus@microchip.com>

commit bccfb96b59179d4f96cbbd1ddff8fac6d335eae4 upstream.

tx_submit is supposed to push the current transaction descriptor to a
pending queue, waiting for issue_pending() to be called. issue_pending()
must start the transfer, not tx_submit(), thus remove
at_xdmac_start_xfer() from at_xdmac_tx_submit(). Clients of at_xdmac that
assume that tx_submit() starts the transfer must be updated and call
dma_async_issue_pending() if they miss to call it (one example is
atmel_serial).

As the at_xdmac_start_xfer() is now called only from
at_xdmac_advance_work() when !at_xdmac_chan_is_enabled(), the
at_xdmac_chan_is_enabled() check is no longer needed in
at_xdmac_start_xfer(), thus remove it.

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20211215110115.191749-2-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/dma/at_xdmac.c | 6 ------
1 file changed, 6 deletions(-)

--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -338,9 +338,6 @@ static void at_xdmac_start_xfer(struct a

dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, first);

- if (at_xdmac_chan_is_enabled(atchan))
- return;
-
/* Set transfer as active to not try to start it again. */
first->active_xfer = true;

@@ -430,9 +427,6 @@ static dma_cookie_t at_xdmac_tx_submit(s
dev_vdbg(chan2dev(tx->chan), "%s: atchan 0x%p, add desc 0x%p to xfers_list\n",
__func__, atchan, desc);
list_add_tail(&desc->xfer_node, &atchan->xfers_list);
- if (list_is_singular(&atchan->xfers_list))
- at_xdmac_start_xfer(atchan, desc);
-
spin_unlock_irqrestore(&atchan->lock, irqflags);
return cookie;
}