dmaengine: at_xdmac: Don't start transactions at tx_submit level

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>

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index e18abbd..9a62029 100644 (file)
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -385,9 +385,6 @@ static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
 
        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;
 
@@ -479,9 +476,6 @@ static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx)
        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;
 }