dmaengine: stm32-dma: pass DMA_SxSCR value to stm32_dma_handle_chan_done()

stm32_dma_handle_chan_done() is called on Transfer Complete interrupt.
As DMA_SxSCR register is read in interrupt handler, pass the value as
parameter of stm32_dma_handle_chan_done(). Also return directly if
chan->desc is null to remove one ident level.
Then, stm32_dma_configure_next_sg() is doing something only if
Double-Buffer Mode (DBM) is enabled, so, check it is enabled prior calling
stm32_dma_configure_next_sg(), to remove one ident level in
stm32_dma_configure_next_sg().

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20220505115611.38845-3-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: ADESTM

drivers/dma/stm32-dma.c

@@ -612,38 +612,38 @@ static void stm32_dma_configure_next_sg(struct stm32_dma_chan *chan)
 	id = chan->id;
 	dma_scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
 
-	if (dma_scr & STM32_DMA_SCR_DBM) {
-		sg_req = &chan->desc->sg_req[chan->next_sg];
-
-		if (dma_scr & STM32_DMA_SCR_CT) {
-			dma_sm0ar = sg_req->chan_reg.dma_sm0ar;
-			stm32_dma_write(dmadev, STM32_DMA_SM0AR(id), dma_sm0ar);
-			dev_dbg(chan2dev(chan), "CT=1 <=> SM0AR: 0x%08x\n",
-				stm32_dma_read(dmadev, STM32_DMA_SM0AR(id)));
-		} else {
-			dma_sm1ar = sg_req->chan_reg.dma_sm1ar;
-			stm32_dma_write(dmadev, STM32_DMA_SM1AR(id), dma_sm1ar);
-			dev_dbg(chan2dev(chan), "CT=0 <=> SM1AR: 0x%08x\n",
-				stm32_dma_read(dmadev, STM32_DMA_SM1AR(id)));
-		}
+	sg_req = &chan->desc->sg_req[chan->next_sg];
+
+	if (dma_scr & STM32_DMA_SCR_CT) {
+		dma_sm0ar = sg_req->chan_reg.dma_sm0ar;
+		stm32_dma_write(dmadev, STM32_DMA_SM0AR(id), dma_sm0ar);
+		dev_dbg(chan2dev(chan), "CT=1 <=> SM0AR: 0x%08x\n",
+			stm32_dma_read(dmadev, STM32_DMA_SM0AR(id)));
+	} else {
+		dma_sm1ar = sg_req->chan_reg.dma_sm1ar;
+		stm32_dma_write(dmadev, STM32_DMA_SM1AR(id), dma_sm1ar);
+		dev_dbg(chan2dev(chan), "CT=0 <=> SM1AR: 0x%08x\n",
+			stm32_dma_read(dmadev, STM32_DMA_SM1AR(id)));
 	}
 }
 
-static void stm32_dma_handle_chan_done(struct stm32_dma_chan *chan)
+static void stm32_dma_handle_chan_done(struct stm32_dma_chan *chan, u32 scr)
 {
-	if (chan->desc) {
-		if (chan->desc->cyclic) {
-			vchan_cyclic_callback(&chan->desc->vdesc);
-			stm32_dma_sg_inc(chan);
+	if (!chan->desc)
+		return;
+
+	if (chan->desc->cyclic) {
+		vchan_cyclic_callback(&chan->desc->vdesc);
+		stm32_dma_sg_inc(chan);
+		if (scr & STM32_DMA_SCR_DBM)
 			stm32_dma_configure_next_sg(chan);
-		} else {
-			chan->busy = false;
-			if (chan->next_sg == chan->desc->num_sgs) {
-				vchan_cookie_complete(&chan->desc->vdesc);
-				chan->desc = NULL;
-			}
-			stm32_dma_start_transfer(chan);
+	} else {
+		chan->busy = false;
+		if (chan->next_sg == chan->desc->num_sgs) {
+			vchan_cookie_complete(&chan->desc->vdesc);
+			chan->desc = NULL;
 		}
+		stm32_dma_start_transfer(chan);
 	}
 }
 
@@ -680,7 +680,7 @@ static irqreturn_t stm32_dma_chan_irq(int irq, void *devid)
 	if (status & STM32_DMA_TCI) {
 		stm32_dma_irq_clear(chan, STM32_DMA_TCI);
 		if (scr & STM32_DMA_SCR_TCIE)
-			stm32_dma_handle_chan_done(chan);
+			stm32_dma_handle_chan_done(chan, scr);
 		status &= ~STM32_DMA_TCI;
 	}