media: coda: clear error return value before picture run

The error return value is not written by some firmware codecs, such as
MPEG-2 decode on CodaHx4. Clear the error return value before starting
the picture run to avoid misinterpreting unrelated values returned by
sequence initialization as error return value.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/coda/coda-bit.c

@@ -2010,6 +2010,9 @@ static int coda_prepare_decode(struct coda_ctx *ctx)
 	/* Clear decode success flag */
 	coda_write(dev, 0, CODA_RET_DEC_PIC_SUCCESS);
 
+	/* Clear error return value */
+	coda_write(dev, 0, CODA_RET_DEC_PIC_ERR_MB);
+
 	trace_coda_dec_pic_run(ctx, meta);
 
 	coda_command_async(ctx, CODA_COMMAND_PIC_RUN);