On Sat, Jun 29, 2024 at 02:52:04PM +0300, Laurent Pinchart wrote: > On Sat, Jun 29, 2024 at 11:34:11AM +0000, Sakari Ailus wrote: > > On Sat, Jun 29, 2024 at 01:52:22PM +0300, Laurent Pinchart wrote: > > > On Sat, Jun 29, 2024 at 08:56:09AM +0000, Sakari Ailus wrote: > > > > Hi Laurent, > > > > > > > > Thanks for the patch. > > > > > > > > On Sat, Jun 29, 2024 at 12:26:03AM +0300, Laurent Pinchart wrote: > > > > > When updating the link frequency control range in response to a format > > > > > change, the minimum value passed to the __v4l2_ctrl_modify_range() > > > > > function is hardcoded to 0, while there's no guarantee that the first > > > > > link frequency in the menu is valid for the selected format. Fix it by > > > > > getting using the index of the first bit set in the valid link > > > > > frequencies mask. > > > > > > > > Is this a problem? The bitmask does tell which ones are valid, doesn't it? > > > > > > I noticed that the new range wasn't applied in my sensor driver when the > > > minimum was set to 0 and the mask didn't include that bit. However, > > > that's because I had the default value wrong, which caused > > > __v4l2_ctrl_modify_range() to error out. I thought the same applied to > > > the minimum, but that doesn't seem to be the case. Isn't it still > > > clearer to set the correct minimum, given that it is already computed > > > anyway, to be used as a default value ? > > > > I guess from user space point of view this could be helpful, yes. I'm fine > > with changing this. > > Another option would be for the control framework to adjust the minimum > and maximum based on the mask. I wonder what Hans (now cc'd) thinks. I think it's actually a good idea, given that the minimum and maximum could change dynamically anyway. > > > > > The minimum value will also be zero after control initialisation before > > > > this function gets called. This should be also taken into account. > > > > > > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > > > > --- > > > > > I noticed this issue in the CCS driver while working on a different > > > > > sensor driver. I haven't tested this patch. > > > > > --- > > > > > drivers/media/i2c/ccs/ccs-core.c | 12 ++++++++---- > > > > > 1 file changed, 8 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c > > > > > index e1ae0f9fad43..5257dc4912ae 100644 > > > > > --- a/drivers/media/i2c/ccs/ccs-core.c > > > > > +++ b/drivers/media/i2c/ccs/ccs-core.c > > > > > @@ -2143,6 +2143,7 @@ static int ccs_set_format_source(struct v4l2_subdev *subdev, > > > > > *old_csi_format = sensor->csi_format; > > > > > unsigned long *valid_link_freqs; > > > > > u32 code = fmt->format.code; > > > > > + unsigned int min, max; > > > > > unsigned int i; > > > > > int rval; > > > > > > > > > > @@ -2179,10 +2180,13 @@ static int ccs_set_format_source(struct v4l2_subdev *subdev, > > > > > &sensor->valid_link_freqs[sensor->csi_format->compressed > > > > > - sensor->compressed_min_bpp]; > > > > > > > > > > - __v4l2_ctrl_modify_range( > > > > > - sensor->link_freq, 0, > > > > > - __fls(*valid_link_freqs), ~*valid_link_freqs, > > > > > - __ffs(*valid_link_freqs)); > > > > > + min = __ffs(*valid_link_freqs); > > > > > + man = __fls(*valid_link_freqs); > > > > > + > > > > > + ret = __v4l2_ctrl_modify_range(sensor->link_freq, min, max, > > > > > + ~*valid_link_freqs, min); > > > > > > > > As this doesn't effect any actual change the applying of which could fail, > > > > you'd have to have an issue with the argument values themselves. I wouldn't > > > > add a check here. Although if you do, the sensor configuration should be > > > > returned to the state before the call which would probably be worth a new > > > > patch. > > > > > > The lack of a similar check caused my driver to silently keep the > > > current range, and it took me a while to debug that. I however agree > > > that, if the arguments are right, the check isn't needed. Maybe it can > > > be dropped, as the arguments are correct. > > > > Alternatively there should be a dev_warn(), too, that this is a driver bug. > > Do you think we should add the warning to the __v4l2_ctrl_modify_range() > function, or are there use cases where it could fail during normal > operation ? If modifying the range results in changing the control value, then this results in (on I²C devices) an I²C write that can fail. The CCS driver writes the configuration to the sensor when streaming starts so there's no actual write operation resulting from this. > > > > > > + if (ret) > > > > > + return ret; > > > > > > > > > > return ccs_pll_update(sensor); > > > > > } > > > > > > > > > > base-commit: afcd48134c58d6af45fb3fdb648f1260b20f2326 > -- Sakari Ailus
