media: staging: rkisp1: isp: add a warning and debugfs var for irq delay

The signal RKISP1_CIF_ISP_FRAME is set when the ISP completes
outputting the frame to the next block in the pipeline.
In order to keep buffer synchronization we assume that the
RKISP1_CIF_ISP_V_START signal never arrives together with the
RKISP1_CIF_ISP_FRAME signal.
In case those signals arrive together then the code is not able to
tell if the RKISP1_CIF_ISP_FRAME signal relates to the frame of
the current v-start or the previous. This patch adds a WARN_ONCE
and a debugfs var to catch it.
Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/staging/media/rkisp1/rkisp1-common.h

@@ -326,6 +326,7 @@ struct rkisp1_debug {
 	unsigned long outform_size_error;
 	unsigned long img_stabilization_size_error;
 	unsigned long inform_size_error;
+	unsigned long irq_delay;
 	unsigned long mipi_error;
 	unsigned long stats_error;
 	unsigned long stop_timeout[2];

drivers/staging/media/rkisp1/rkisp1-dev.c

@@ -444,6 +444,8 @@ static void rkisp1_debug_init(struct rkisp1_device *rkisp1)
 			     &debug->img_stabilization_size_error);
 	debugfs_create_ulong("inform_size_error", 0444,  debug->debugfs_dir,
 			     &debug->inform_size_error);
+	debugfs_create_ulong("irq_delay", 0444,  debug->debugfs_dir,
+			     &debug->irq_delay);
 	debugfs_create_ulong("mipi_error", 0444, debug->debugfs_dir,
 			     &debug->mipi_error);
 	debugfs_create_ulong("stats_error", 0444, debug->debugfs_dir,

drivers/staging/media/rkisp1/rkisp1-isp.c

@@ -1123,6 +1123,10 @@ void rkisp1_isp_isr(struct rkisp1_device *rkisp1)
 	if (status & RKISP1_CIF_ISP_V_START) {
 		rkisp1->isp.frame_sequence++;
 		rkisp1_isp_queue_event_sof(&rkisp1->isp);
+		if (status & RKISP1_CIF_ISP_FRAME) {
+			WARN_ONCE(1, "irq delay is too long, buffers might not be in sync\n");
+			rkisp1->debug.irq_delay++;
+		}
 	}
 	if (status & RKISP1_CIF_ISP_PIC_SIZE_ERROR) {
 		/* Clear pic_size_error */