[PATCH v2 2/6] dmaengine: sun6i: handle the last partial interrupt bank

[James Hilliard]

The number of physical channels need not be a multiple of the number
covered by an interrupt-status register. H3 has twelve channels and
eight channels per bank. Rounding down the number of banks leaves its
channels 8 through 11 without completion handling.

Round up the number of banks to visit, and stop processing the last bank
at num_pchans so unused status bits cannot index past the physical-channel
array. Use the controller's configured bank size for both limits and
the physical-channel index.

Fixes: f008db8c00c1 ("dmaengine: sun6i: Add support for Allwinner H3 (sun8i) variant")
Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
Closes: https://lore.kernel.org/r/20260706065650.34B131F00A3A@xxxxxxxxxxxxxxx
Signed-off-by: James Hilliard <james.hilliard1@xxxxxxxxx>
---
 drivers/dma/sun6i-dma.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 9d94a37fcf10..0a9645171180 100644
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -587,12 +587,13 @@ static void sun6i_dma_tasklet(struct tasklet_struct *t)
 static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 {
 	struct sun6i_dma_dev *sdev = dev_id;
+	u32 channels_per_reg = sdev->cfg->num_channels_per_reg;
 	struct sun6i_vchan *vchan;
 	struct sun6i_pchan *pchan;
 	int i, j, ret = IRQ_NONE;
 	u32 status;
 
-	for (i = 0; i < sdev->num_pchans / sdev->cfg->num_channels_per_reg; i++) {
+	for (i = 0; i < DIV_ROUND_UP(sdev->num_pchans, channels_per_reg); i++) {
 		status = sun6i_read_irq_stat(sdev, i);
 		if (!status)
 			continue;
@@ -602,8 +603,9 @@ static irqreturn_t sun6i_dma_interrupt(int irq, void *dev_id)
 
 		sun6i_write_irq_stat(sdev, i, status);
 
-		for (j = 0; (j < sdev->cfg->num_channels_per_reg) && status; j++) {
-			pchan = sdev->pchans + i * sdev->cfg->num_channels_per_reg + j;
+		for (j = 0; j < channels_per_reg &&
+		     i * channels_per_reg + j < sdev->num_pchans && status; j++) {
+			pchan = sdev->pchans + i * channels_per_reg + j;
 			vchan = pchan->vchan;
 			if (vchan && (status & vchan->irq_type)) {
 				if (vchan->cyclic) {

-- 
2.53.0