Re: [PATCH] media: i2c: ov2659: speedup probe if no device connected

[Lad, Prabhakar]

On Mon, Dec 21, 2015 at 1:54 PM, Grygorii Strashko
 wrote:
> The ov2659 driver performs device detection and initialization in the
> following way:
>  - send reset command REG_SOFTWARE_RESET
>  - load array of predefined register's setting (~150 values)
>  - read device version REG_SC_CHIP_ID_H/REG_SC_CHIP_ID_L
>  - check version and exit if invalid.
>
> As result, for not connected device there will be >~150 i2c transactions
> executed before device version checking and exit (there are no
> failures detected because ov2659 declared as I2C_CLIENT_SCCB and NACKs
> are ignored in this case).
>
> Let's fix that by checking the chip version first and start
> initialization only if it's supported.
>
> Cc: Benoit Parrot 
> Signed-off-by: Grygorii Strashko 

Acked-by: Lad, Prabhakar 

Cheers,
--Prabhakar Lad

> ---
>  drivers/media/i2c/ov2659.c | 8 +++-
>  1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/i2c/ov2659.c b/drivers/media/i2c/ov2659.c
> index 49109f4..9b7b78c 100644
> --- a/drivers/media/i2c/ov2659.c
> +++ b/drivers/media/i2c/ov2659.c
> @@ -1321,10 +1321,6 @@ static int ov2659_detect(struct v4l2_subdev *sd)
> }
> usleep_range(1000, 2000);
>
> -   ret = ov2659_init(sd, 0);
> -   if (ret < 0)
> -   return ret;
> -
> /* Check sensor revision */
> ret = ov2659_read(client, REG_SC_CHIP_ID_H, );
> if (!ret)
> @@ -1338,8 +1334,10 @@ static int ov2659_detect(struct v4l2_subdev *sd)
> dev_err(>dev,
> "Sensor detection failed (%04X, %d)\n",
> id, ret);
> -   else
> +   else {
> dev_info(>dev, "Found OV%04X sensor\n", id);
> +   ret = ov2659_init(sd, 0);
> +   }
> }
>
> return ret;
> --
> 2.6.4
>
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[PATCH] media: i2c: ov2659: speedup probe if no device connected

[Grygorii Strashko]

The ov2659 driver performs device detection and initialization in the
following way:
 - send reset command REG_SOFTWARE_RESET
 - load array of predefined register's setting (~150 values)
 - read device version REG_SC_CHIP_ID_H/REG_SC_CHIP_ID_L
 - check version and exit if invalid.

As result, for not connected device there will be >~150 i2c transactions
executed before device version checking and exit (there are no
failures detected because ov2659 declared as I2C_CLIENT_SCCB and NACKs
are ignored in this case).

Let's fix that by checking the chip version first and start
initialization only if it's supported.

Cc: Benoit Parrot 
Signed-off-by: Grygorii Strashko 
---
 drivers/media/i2c/ov2659.c | 8 +++-
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/media/i2c/ov2659.c b/drivers/media/i2c/ov2659.c
index 49109f4..9b7b78c 100644
--- a/drivers/media/i2c/ov2659.c
+++ b/drivers/media/i2c/ov2659.c
@@ -1321,10 +1321,6 @@ static int ov2659_detect(struct v4l2_subdev *sd)
}
usleep_range(1000, 2000);
 
-   ret = ov2659_init(sd, 0);
-   if (ret < 0)
-   return ret;
-
/* Check sensor revision */
ret = ov2659_read(client, REG_SC_CHIP_ID_H, );
if (!ret)
@@ -1338,8 +1334,10 @@ static int ov2659_detect(struct v4l2_subdev *sd)
dev_err(>dev,
"Sensor detection failed (%04X, %d)\n",
id, ret);
-   else
+   else {
dev_info(>dev, "Found OV%04X sensor\n", id);
+   ret = ov2659_init(sd, 0);
+   }
}
 
return ret;
-- 
2.6.4

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