linux-kernel - [PATCH 02/10] dma: imx-sdma: don't update BD in isr routine

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Date:	Mon, 16 May 2016 17:37:50 +0900
From:	Jiada Wang <jiada_wang@...tor.com>
To:	<vinod.koul@...el.com>, <dan.j.williams@...el.com>
CC:	<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<george_davis@...tor.com>, <jiada_wang@...tor.com>
Subject: [PATCH 02/10] dma: imx-sdma: don't update BD in isr routine

commit d1a792f3b407 ("Update imx-sdma cyclic handling to report residue")
moves updating of BD to isr routine, to avoid stop
of cyclic dma, but there is chance 'new' isr comes before the 'old'
tasklet can be fired, thus cause data loss due to missing of one
tasklet. So move updating of BD back to tasklet.

Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
---
 drivers/dma/imx-sdma.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 1f1b64b..887e4e5 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -656,12 +656,6 @@ static void sdma_event_disable(struct sdma_channel *sdmac, unsigned int event)
 
 static void sdma_handle_channel_loop(struct sdma_channel *sdmac)
 {
-	if (sdmac->desc.callback)
-		sdmac->desc.callback(sdmac->desc.callback_param);
-}
-
-static void sdma_update_channel_loop(struct sdma_channel *sdmac)
-{
 	struct sdma_buffer_descriptor *bd;
 
 	/*
@@ -685,6 +679,9 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac)
 			sdmac->chn_real_count = bd->mode.count;
 			bd->mode.count = sdmac->chn_count;
 		}
+
+		if (sdmac->desc.callback)
+			sdmac->desc.callback(sdmac->desc.callback_param);
 	}
 }
 
@@ -740,9 +737,6 @@ static irqreturn_t sdma_int_handler(int irq, void *dev_id)
 		int channel = fls(stat) - 1;
 		struct sdma_channel *sdmac = &sdma->channel[channel];
 
-		if (sdmac->flags & IMX_DMA_SG_LOOP)
-			sdma_update_channel_loop(sdmac);
-
 		tasklet_schedule(&sdmac->tasklet);
 
 		__clear_bit(channel, &stat);
-- 
2.4.5