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[3/3] exynos4-is: Wait for 100us before opening sensor

Message ID 1453133427-20793-4-git-send-email-j.anaszewski@samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

Jacek Anaszewski Jan. 18, 2016, 4:10 p.m. UTC 
Some user space use cases result in kernel hangup on the HIC_OPEN_SENSOR
command write. In case when a minimalistic application is used for setting
up the streaming, the hangups occur only occasionally. In case of GStreamer
use cases it is always the case.

Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
---
 drivers/media/platform/exynos4-is/fimc-is.c |    6 ++++++
 1 file changed, 6 insertions(+)
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Patch

diff --git a/drivers/media/platform/exynos4-is/fimc-is.c b/drivers/media/platform/exynos4-is/fimc-is.c
index 123772f..3f50856 100644
--- a/drivers/media/platform/exynos4-is/fimc-is.c
+++ b/drivers/media/platform/exynos4-is/fimc-is.c
@@ -631,6 +631,12 @@  static int fimc_is_hw_open_sensor(struct fimc_is *is,
 
 	fimc_is_mem_barrier();
 
+	/*
+	 * Some user space use cases hang up here without this
+	 * empirically chosen delay.
+	 */
+	udelay(100);
+
 	mcuctl_write(HIC_OPEN_SENSOR, is, MCUCTL_REG_ISSR(0));
 	mcuctl_write(is->sensor_index, is, MCUCTL_REG_ISSR(1));
 	mcuctl_write(sensor->drvdata->id, is, MCUCTL_REG_ISSR(2));