DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DCC02619E3
IronPort-SDR: Bvkk+zeNVoYpl6/X08jQky86RTfzInacLNpyWnaOcY94bK/5FheoRBpt9r3hk2M471Vo8/9yCj
 QX0BMUJuDPl5jfYUa7eNemFUuf+Ix+xx1Vyxqulw+bQ7uoIzk6NVyvCoF5FNyOdQerTrKIEYr/
 SAaLuRxQyReLCqwXvk6l7LR5GHFvaDWmJSgzJEJtIm4Ny8N+vMyfZa3RCVZivuI61IYisy+OSa
 jJQa+2XfcHH+7+2M+EJY34r6RXXczJxZgeAbNH+lTUw6MbrAomYCEpgUY6sAybKgOPMF6550Py
 riSPud519zcvY+GRDWVEpzRf
From:   Tudor Ambarus <tudor.ambarus@microchip.com>
To:     <ludovic.desroches@microchip.com>, <vkoul@kernel.org>,
        <richard.genoud@gmail.com>, <gregkh@linuxfoundation.org>,
        <jirislaby@kernel.org>
CC:     <nicolas.ferre@microchip.com>, <alexandre.belloni@bootlin.com>,
        <mripard@kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-serial@vger.kernel.org>,
        Tudor Ambarus <tudor.ambarus@microchip.com>
Subject: [PATCH 01/13] dmaengine: at_xdmac: Don't start transactions at tx_submit level
Date:   Tue, 16 Nov 2021 13:20:24 +0200
Message-ID: <20211116112036.96349-2-tudor.ambarus@microchip.com>
In-Reply-To: <20211116112036.96349-1-tudor.ambarus@microchip.com>
References: <20211116112036.96349-1-tudor.ambarus@microchip.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
Precedence: bulk

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().
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.

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).

Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---
 drivers/dma/at_xdmac.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 275a76f188ae..ccf796a3b9f3 100644
--- 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;
 }
-- 
2.25.1