linux-kernel - [PATCH 2/4] dmaengine: mediatek: do not issue a new desc if one is still current

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Message-ID: <CABnWg9vHxXSxDeBxjMCOHtCDogL+jUXMq9-SCC8x3zmaV8wL0g@mail.gmail.com>
Date:   Mon, 3 May 2021 08:26:29 -0700
From:   Guillaume Ranquet <granquet@...libre.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Sean Wang <sean.wang@...iatek.com>, Vinod Koul <vkoul@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/4] dmaengine: mediatek: do not issue a new desc if one is
 still current

Avoid issuing a new desc if one is still being processed as this can
lead to some desc never being marked as completed.

Signed-off-by: Guillaume Ranquet <granquet@...libre.com>

diff --git a/drivers/dma/mediatek/mtk-uart-apdma.c
b/drivers/dma/mediatek/mtk-uart-apdma.c
index 4610dbdde75e..249cabddb7ee 100644
--- a/drivers/dma/mediatek/mtk-uart-apdma.c
+++ b/drivers/dma/mediatek/mtk-uart-apdma.c
@@ -204,14 +204,9 @@ static void mtk_uart_apdma_start_rx(struct mtk_chan *c)

 static void mtk_uart_apdma_tx_handler(struct mtk_chan *c)
 {
-	struct mtk_uart_apdma_desc *d = c->desc;
-
 	mtk_uart_apdma_write(c, VFF_INT_FLAG, VFF_TX_INT_CLR_B);
 	mtk_uart_apdma_write(c, VFF_INT_EN, VFF_INT_EN_CLR_B);
 	mtk_uart_apdma_write(c, VFF_EN, VFF_EN_CLR_B);
-
-	list_del(&d->vd.node);
-	vchan_cookie_complete(&d->vd);
 }

 static void mtk_uart_apdma_rx_handler(struct mtk_chan *c)
@@ -242,9 +237,17 @@ static void mtk_uart_apdma_rx_handler(struct mtk_chan *c)

 	c->rx_status = d->avail_len - cnt;
 	mtk_uart_apdma_write(c, VFF_RPT, wg);
+}

-	list_del(&d->vd.node);
-	vchan_cookie_complete(&d->vd);
+static void mtk_uart_apdma_chan_complete_handler(struct mtk_chan *c)
+{
+	struct mtk_uart_apdma_desc *d = c->desc;
+
+	if (d) {
+		list_del(&d->vd.node);
+		vchan_cookie_complete(&d->vd);
+		c->desc = NULL;
+	}
 }

 static irqreturn_t mtk_uart_apdma_irq_handler(int irq, void *dev_id)
@@ -258,6 +261,7 @@ static irqreturn_t mtk_uart_apdma_irq_handler(int
irq, void *dev_id)
 		mtk_uart_apdma_rx_handler(c);
 	else if (c->dir == DMA_MEM_TO_DEV)
 		mtk_uart_apdma_tx_handler(c);
+	mtk_uart_apdma_chan_complete_handler(c);
 	spin_unlock_irqrestore(&c->vc.lock, flags);

 	return IRQ_HANDLED;
@@ -363,7 +367,7 @@ static void mtk_uart_apdma_issue_pending(struct
dma_chan *chan)
 	unsigned long flags;

 	spin_lock_irqsave(&c->vc.lock, flags);
-	if (vchan_issue_pending(&c->vc)) {
+	if (vchan_issue_pending(&c->vc) && !c->desc) {
 		vd = vchan_next_desc(&c->vc);
 		c->desc = to_mtk_uart_apdma_desc(&vd->tx);

-- 
2.26.3