[PATCH AUTOSEL 4.14 42/89] media: imx: mipi csi-2: Don't fail if initial state times-out

Sasha Levin sashal at kernel.org
Sun Sep 22 18:56:30 UTC 2019

From: Ezequiel Garcia <ezequiel at collabora.com>

[ Upstream commit 0d5078c7172c46db6c58718d817b9fcf769554b4 ]

Not all sensors will be able to guarantee a proper initial state.
This may be either because the driver is not properly written,
or (probably unlikely) because the hardware won't support it.

While the right solution in the former case is to fix the sensor
driver, the real world not always allows right solutions, due to lack
of available documentation and support on these sensors.

Let's relax this requirement, and allow the driver to support stream start,
even if the sensor initial sequence wasn't the expected.

Also improve the warning message to better explain the problem and provide
a hint that the sensor driver needs to be fixed.

Signed-off-by: Ezequiel Garcia <ezequiel at collabora.com>
Signed-off-by: Fabio Estevam <festevam at gmail.com>
Reviewed-by: Steve Longerbeam <slongerbeam at gmail.com>
Reviewed-by: Philipp Zabel <p.zabel at pengutronix.de>
Signed-off-by: Sakari Ailus <sakari.ailus at linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
 drivers/staging/media/imx/imx6-mipi-csi2.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
index 5061f3f524fd5..c28f65c5427d1 100644
--- a/drivers/staging/media/imx/imx6-mipi-csi2.c
+++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
@@ -247,7 +247,7 @@ static int __maybe_unused csi2_dphy_wait_ulp(struct csi2_dev *csi2)
 /* Waits for low-power LP-11 state on data and clock lanes. */
-static int csi2_dphy_wait_stopstate(struct csi2_dev *csi2)
+static void csi2_dphy_wait_stopstate(struct csi2_dev *csi2)
 	u32 mask, reg;
 	int ret;
@@ -258,11 +258,9 @@ static int csi2_dphy_wait_stopstate(struct csi2_dev *csi2)
 	ret = readl_poll_timeout(csi2->base + CSI2_PHY_STATE, reg,
 				 (reg & mask) == mask, 0, 500000);
 	if (ret) {
-		v4l2_err(&csi2->sd, "LP-11 timeout, phy_state = 0x%08x\n", reg);
-		return ret;
+		v4l2_warn(&csi2->sd, "LP-11 wait timeout, likely a sensor driver bug, expect capture failures.\n");
+		v4l2_warn(&csi2->sd, "phy_state = 0x%08x\n", reg);
-	return 0;
 /* Wait for active clock on the clock lane. */
@@ -320,9 +318,7 @@ static int csi2_start(struct csi2_dev *csi2)
 	csi2_enable(csi2, true);
 	/* Step 5 */
-	ret = csi2_dphy_wait_stopstate(csi2);
-	if (ret)
-		goto err_assert_reset;
+	csi2_dphy_wait_stopstate(csi2);
 	/* Step 6 */
 	ret = v4l2_subdev_call(csi2->src_sd, video, s_stream, 1);

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