linux-kernel - [PATCH 3/3] dmaengine: stm32-mdma: set in_flight

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Message-ID: <20231004163531.2864160-3-amelie.delaunay@foss.st.com>
Date:   Wed, 4 Oct 2023 18:35:30 +0200
From:   Amelie Delaunay <amelie.delaunay@...s.st.com>
To:     Vinod Koul <vkoul@...nel.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Amelie Delaunay <amelie.delaunay@...s.st.com>
CC:     <stable@...r.kernel.org>, <dmaengine@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/3] dmaengine: stm32-mdma: set in_flight_bytes in case CRQA flag is set

CRQA flag is set by hardware when the channel request become active and
the channel is enabled. It is cleared by hardware, when the channel request
is completed.
So when it is set, it means MDMA is transferring bytes.
This information is useful in case of STM32 DMA and MDMA chaining,
especially when the user pauses DMA before stopping it, to trig one last
MDMA transfer to get the latest bytes of the SRAM buffer to the
destination buffer.
STM32 DCMI driver can then use this to know if the last MDMA transfer in
case of chaining is done.

Fixes: 696874322771 ("dmaengine: stm32-mdma: add support to be triggered by STM32 DMA")
Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
Cc: stable@...r.kernel.org
---
 drivers/dma/stm32-mdma.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index da73e13b8c9d..bae08b3f55c7 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -1318,7 +1318,8 @@ static int stm32_mdma_slave_config(struct dma_chan *c,
 
 static size_t stm32_mdma_desc_residue(struct stm32_mdma_chan *chan,
 				      struct stm32_mdma_desc *desc,
-				      u32 curr_hwdesc)
+				      u32 curr_hwdesc,
+				      struct dma_tx_state *state)
 {
 	struct stm32_mdma_device *dmadev = stm32_mdma_get_dev(chan);
 	struct stm32_mdma_hwdesc *hwdesc;
@@ -1342,6 +1343,10 @@ static size_t stm32_mdma_desc_residue(struct stm32_mdma_chan *chan,
 	cbndtr = stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id));
 	residue += cbndtr & STM32_MDMA_CBNDTR_BNDT_MASK;
 
+	state->in_flight_bytes = 0;
+	if (chan->chan_config.m2m_hw && (cisr & STM32_MDMA_CISR_CRQA))
+		state->in_flight_bytes = cbndtr & STM32_MDMA_CBNDTR_BNDT_MASK;
+
 	if (!chan->mem_burst)
 		return residue;
 
@@ -1371,11 +1376,10 @@ static enum dma_status stm32_mdma_tx_status(struct dma_chan *c,
 
 	vdesc = vchan_find_desc(&chan->vchan, cookie);
 	if (chan->desc && cookie == chan->desc->vdesc.tx.cookie)
-		residue = stm32_mdma_desc_residue(chan, chan->desc,
-						  chan->curr_hwdesc);
+		residue = stm32_mdma_desc_residue(chan, chan->desc, chan->curr_hwdesc, state);
 	else if (vdesc)
-		residue = stm32_mdma_desc_residue(chan,
-						  to_stm32_mdma_desc(vdesc), 0);
+		residue = stm32_mdma_desc_residue(chan, to_stm32_mdma_desc(vdesc), 0, state);
+
 	dma_set_residue(state, residue);
 
 	spin_unlock_irqrestore(&chan->vchan.lock, flags);
-- 
2.25.1