[PATCH v2 1/5] media: qcom: camss: vfe-17x: Fix write master buffer done being dropped

[Hitesh Patel]

The VFE 17x interrupt handler reads and clears the bus status
registers on every interrupt, but only acts on the per write master
BUF_DONE bits when bit 9 of IRQ_STATUS_0 is set as well. Bit 9 is the
ping-pong flag of image master 1. It has nothing to do with the other
write masters, and it is not guaranteed to be set in the same
interrupt in which a write master reports a completed buffer.

The bus status is read-to-clear. When a buffer done arrives while bit
9 is not set, the handler clears the status and never calls
wm_done() for it. The buffer stays queued in the driver and the video
node never receives that frame.

With one RDI streaming this is rare. With two RDIs streaming on the
same VFE, for instance two virtual channels demultiplexed by the CSID,
the interrupt rate doubles and one of the two lines loses buffer done
events continuously.

Act on the bus status alone, as the other gen2 VFE handlers do.

Fixes: 7319cdf189bb ("media: camss: Add support for VFE hardware version Titan 170")
Signed-off-by: Hitesh Patel <hitesh@xxxxxxxxxxxxxx>
---
 drivers/media/platform/qcom/camss/camss-vfe-17x.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe-17x.c b/drivers/media/platform/qcom/camss/camss-vfe-17x.c
index e5ee7e717..c011f64f6 100644
--- a/drivers/media/platform/qcom/camss/camss-vfe-17x.c
+++ b/drivers/media/platform/qcom/camss/camss-vfe-17x.c
@@ -364,9 +364,8 @@ static irqreturn_t vfe_isr(int irq, void *dev)
 			vfe->isr_ops.comp_done(vfe, i);
 
 	for (wm = 0; wm < MSM_VFE_IMAGE_MASTERS_NUM; wm++)
-		if (status0 & BIT(9))
-			if (vfe_bus_status[1] & STATUS1_WM_CLIENT_BUF_DONE(wm))
-				vfe->isr_ops.wm_done(vfe, wm);
+		if (vfe_bus_status[1] & STATUS1_WM_CLIENT_BUF_DONE(wm))
+			vfe->isr_ops.wm_done(vfe, wm);
 
 	return IRQ_HANDLED;
 }
-- 
2.43.0