Hi Laurent,
Am Mittwoch, den 28.05.2014, 13:30 +0200 schrieb Laurent Pinchart:
> Hi Philipp,
>
> Thank you for the patch.
>
> On Monday 26 May 2014 15:59:35 Philipp Zabel wrote:
> > The read mode register bits 8 and 9 are set and marked as reserved.
> > Don't clear them.
>
> Good catch. Have you noticed any issue in practice ?
No. I have no idea what (if anything) those bits actually do, though.
> > Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> > ---
> > drivers/media/i2c/mt9v032.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/i2c/mt9v032.c b/drivers/media/i2c/mt9v032.c
> > index 33a110a..052e754 100644
> > --- a/drivers/media/i2c/mt9v032.c
> > +++ b/drivers/media/i2c/mt9v032.c
> > @@ -415,6 +415,7 @@ static int mt9v032_s_stream(struct v4l2_subdev *subdev,
> > int enable) struct i2c_client *client = v4l2_get_subdevdata(subdev);
> > struct mt9v032 *mt9v032 = to_mt9v032(subdev);
> > struct v4l2_rect *crop = &mt9v032->crop;
> > + unsigned int read_mode;
> > unsigned int hbin;
> > unsigned int vbin;
> > int ret;
> > @@ -425,9 +426,11 @@ static int mt9v032_s_stream(struct v4l2_subdev *subdev,
> > int enable) /* Configure the window size and row/column bin */
> > hbin = fls(mt9v032->hratio) - 1;
> > vbin = fls(mt9v032->vratio) - 1;
> > - ret = mt9v032_write(client, MT9V032_READ_MODE,
> > - hbin << MT9V032_READ_MODE_COLUMN_BIN_SHIFT |
> > - vbin << MT9V032_READ_MODE_ROW_BIN_SHIFT);
> > + read_mode = mt9v032_read(client, MT9V032_READ_MODE);
>
> Shouldn't you check the return value for errors here ?
Yes, thanks.
> > + read_mode &= ~0xff; /* bits 0x300 are reserved */
>
> What about defining an MT9V032_READ_MODE_RESERVED macro set to 0x0300 and
> using it here ?
I'll do that.
> > + read_mode |= hbin << MT9V032_READ_MODE_COLUMN_BIN_SHIFT |
> > + vbin << MT9V032_READ_MODE_ROW_BIN_SHIFT;
> > + ret = mt9v032_write(client, MT9V032_READ_MODE, read_mode);
>
> I'm tempted to create an mt9v032_write_read_mode function, as the code is
> getting a bit complex:
>
> static int mt9v032_write_read_mode(struct mt9v032 *mt9v032, u16 value)
> {
> struct i2c_client *client = v4l2_get_subdevdata(&mt9v032->subdev);
> int ret;
>
> ret = mt9v032_read(client, MT9V032_READ_MODE);
> if (ret < 0)
> return ret;
>
> ret &= ~MT9V032_READ_MODE_RESERVED;
> ret |= value;
>
> return mt9v032_write(client, MT9V032_READ_MODE, ret);
> }
>
> But I'll leave that up to you, feel free to ignore the suggestion.
I'd rather convert the driver to use regmap so we don't have to open
code those read-modify-writes everywhere.
regards
Philipp
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