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SubjectRe: [PATCH v2 3/5] media: mt9p031: Implement [gs]_register debug calls
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Hi Laurent,

On 30.09.20 13:38, Laurent Pinchart wrote:
> Hi Stefan,
>
> Thank you for the patch.
>
> On Wed, Sep 30, 2020 at 12:51:31PM +0200, Stefan Riedmueller wrote:
>> From: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
>>
>> Implement g_register and s_register v4l2_subdev_core_ops to access
>> camera register directly from userspace for debug purposes.
>
> As the name of the operations imply, this is meant for debug purpose
> only. They are however prone to be abused to configure the sensor from
> userspace in production, which isn't a direction we want to take.
> What's your use case for this ? I'd rather drop this patch and see the
> driver extended with support for more controls if needed

thanks for your feedback.

I get your point. I myself solely use these operations for debugging
purposes but I'm aware that others like to abuse them.

I thought I send it anyway since for me the DEBUG config is enough to
signalize that these operations are not to be used with a productive system.
But I'm OK with dropping this patch if you think it might send the wrong signal.

Regards,
Stefan

>
>> Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
>> Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
>> ---
>> No changes in v2
>> ---
>> drivers/media/i2c/mt9p031.c | 28 ++++++++++++++++++++++++++++
>> 1 file changed, 28 insertions(+)
>>
>> diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
>> index b4c042f418c1..de36025260a8 100644
>> --- a/drivers/media/i2c/mt9p031.c
>> +++ b/drivers/media/i2c/mt9p031.c
>> @@ -703,6 +703,30 @@ static int mt9p031_restore_blc(struct mt9p031 *mt9p031)
>> return 0;
>> }
>>
>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>> +static int mt9p031_g_register(struct v4l2_subdev *sd,
>> + struct v4l2_dbg_register *reg)
>> +{
>> + struct i2c_client *client = v4l2_get_subdevdata(sd);
>> + int ret;
>> +
>> + ret = mt9p031_read(client, reg->reg);
>> + if (ret < 0)
>> + return ret;
>> +
>> + reg->val = ret;
>> + return 0;
>> +}
>> +
>> +static int mt9p031_s_register(struct v4l2_subdev *sd,
>> + struct v4l2_dbg_register const *reg)
>> +{
>> + struct i2c_client *client = v4l2_get_subdevdata(sd);
>> +
>> + return mt9p031_write(client, reg->reg, reg->val);
>> +}
>> +#endif
>> +
>> static int mt9p031_s_ctrl(struct v4l2_ctrl *ctrl)
>> {
>> struct mt9p031 *mt9p031 =
>> @@ -1000,6 +1024,10 @@ static int mt9p031_close(struct v4l2_subdev *subdev, struct v4l2_subdev_fh *fh)
>>
>> static const struct v4l2_subdev_core_ops mt9p031_subdev_core_ops = {
>> .s_power = mt9p031_set_power,
>> +#ifdef CONFIG_VIDEO_ADV_DEBUG
>> + .s_register = mt9p031_s_register,
>> + .g_register = mt9p031_g_register,
>> +#endif
>> };
>>
>> static const struct v4l2_subdev_video_ops mt9p031_subdev_video_ops = {
>

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