[PATCH v2] media: imx: mipi csi-2: Don't fail if initial state times-out

[PATCH v2] media: imx: mipi csi-2: Don't fail if initial state times-out

[Fabio Estevam]

From: Ezequiel Garcia <ezequiel@collabora.com>

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@collabora.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Changes since v1:
- Changed the warning message to better explain the problem and provide
a hint that the sensor driver needs to be fixed. (Phillip)
- Keep printing the phy_state information (Phillip)
- Do not change csi2_dphy_wait_clock_lane() (Phillip/Steve)

 drivers/staging/media/imx/imx6-mipi-csi2.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
index f29e28df36ed..240f992ad2ef 100644
--- a/drivers/staging/media/imx/imx6-mipi-csi2.c
+++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
@@ -243,7 +243,7 @@ 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;
@@ -254,11 +254,11 @@ 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, "Timeout waiting for LP-11 state on all active lanes.\n");
+		v4l2_warn(&csi2->sd, "This is most likely caused by a bug in the sensor driver.\n");
+		v4l2_warn(&csi2->sd, "Capture might fail or contain visual artifacts.\n");
+		v4l2_warn(&csi2->sd, "phy_state = 0x%08x\n", reg);
 	}
-
-	return 0;
 }
 
 /* Wait for active clock on the clock lane. */
@@ -316,9 +316,7 @@ 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);
-- 
2.17.1

Re: [PATCH v2] media: imx: mipi csi-2: Don't fail if initial state times-out

[Steve Longerbeam]

On 6/27/19 3:13 PM, Fabio Estevam wrote:
> From: Ezequiel Garcia <ezequiel@collabora.com>
>
> 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@collabora.com>
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> ---
> Changes since v1:
> - Changed the warning message to better explain the problem and provide
> a hint that the sensor driver needs to be fixed. (Phillip)
> - Keep printing the phy_state information (Phillip)
> - Do not change csi2_dphy_wait_clock_lane() (Phillip/Steve)
>
>   drivers/staging/media/imx/imx6-mipi-csi2.c | 14 ++++++--------
>   1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/staging/media/imx/imx6-mipi-csi2.c b/drivers/staging/media/imx/imx6-mipi-csi2.c
> index f29e28df36ed..240f992ad2ef 100644
> --- a/drivers/staging/media/imx/imx6-mipi-csi2.c
> +++ b/drivers/staging/media/imx/imx6-mipi-csi2.c
> @@ -243,7 +243,7 @@ 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;
> @@ -254,11 +254,11 @@ 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, "Timeout waiting for LP-11 state on all active lanes.\n");
> +		v4l2_warn(&csi2->sd, "This is most likely caused by a bug in the sensor driver.\n");
> +		v4l2_warn(&csi2->sd, "Capture might fail or contain visual artifacts.\n");

I think this should be reduced, something like:

"LP-11 wait timeout, likely a sensor driver bug, expect capture failures"

Steve

> +		v4l2_warn(&csi2->sd, "phy_state = 0x%08x\n", reg);
>   	}
> -
> -	return 0;
>   }
>   
>   /* Wait for active clock on the clock lane. */
> @@ -316,9 +316,7 @@ 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);