Hi Hans,
On Fri, Nov 16, 2018 at 02:31:01PM +0100, Hans Verkuil wrote:
> On 11/16/2018 02:26 PM, Sakari Ailus wrote:
> > Hi Marco, Michael,
> >
> > On Mon, Oct 29, 2018 at 07:24:07PM +0100, Marco Felsch wrote:
> >> From: Michael Grzeschik <m.grzesc...@pengutronix.de>
> >>
> >> This patch implements the framerate selection using the skipping and
> >> readout power-modi features. The power-modi cut the framerate by half
> >> and each context has an independent selection bit. The same applies to
> >> the 2x skipping feature.
> >>
> >> Signed-off-by: Michael Grzeschik <m.grzesc...@pengutronix.de>
> >> Signed-off-by: Marco Felsch <m.fel...@pengutronix.de>
> >>
> >> ---
> >> Changelog
> >>
> >> v2:
> >> - fix updating read mode register, use mt9m111_reg_mask() to update the
> >> relevant bits only. For this purpose add reg_mask field to
> >> struct mt9m111_mode_info.
> >>
> >> drivers/media/i2c/mt9m111.c | 163 ++++++++++++++++++++++++++++++++++++
> >> 1 file changed, 163 insertions(+)
> >>
> >> diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
>
> <snip>
>
> >> +static const struct mt9m111_mode_info *
> >> +mt9m111_find_mode(struct mt9m111 *mt9m111, unsigned int req_fps,
> >> + unsigned int width, unsigned int height)
> >> +{
> >> + const struct mt9m111_mode_info *mode;
> >> + struct v4l2_rect *sensor_rect = &mt9m111->rect;
> >> + unsigned int gap, gap_best = (unsigned int) -1;
> >> + int i, best_gap_idx = 1;
> >> +
> >> + /* find best matched fps */
> >> + for (i = 0; i < MT9M111_NUM_MODES; i++) {
> >> + unsigned int fps = mt9m111_mode_data[i].max_fps;
> >> +
> >> + gap = abs(fps - req_fps);
> >> + if (gap < gap_best) {
> >> + best_gap_idx = i;
> >> + gap_best = gap;
> >> + }
> >
> > Could you use v4l2_find_nearest_size() instead?
> >
> > Also see below...
> >
> >> + }
> >> +
> >> + /*
> >> + * Use context a/b default timing values instead of calculate blanking
> >> + * timing values.
> >> + */
> >> + mode = &mt9m111_mode_data[best_gap_idx];
> >> + mt9m111->ctx = (best_gap_idx == MT9M111_MODE_QSXGA_30FPS) ? &context_a :
> >> + &context_b;
> >> +
> >> + /*
> >> + * Check if current settings support the fps because fps selection is
> >> + * based on the row/col skipping mechanism which has some restriction.
> >> + */
> >> + if (sensor_rect->width != mode->sensor_w ||
> >> + sensor_rect->height != mode->sensor_h ||
> >> + width > mode->max_image_w ||
> >> + height > mode->max_image_h) {
> >> + /* reset sensor window size */
> >> + mt9m111->rect.left = MT9M111_MIN_DARK_COLS;
> >> + mt9m111->rect.top = MT9M111_MIN_DARK_ROWS;
> >> + mt9m111->rect.width = mode->sensor_w;
> >> + mt9m111->rect.height = mode->sensor_h;
> >> +
> >> + /* reset image size */
> >> + mt9m111->width = mode->max_image_w;
> >> + mt9m111->height = mode->max_image_h;
> >> +
> >> + dev_warn(mt9m111->subdev.dev,
> >> + "Warning: update image size %dx%d[%dx%d] ->
> >> %dx%d[%dx%d]\n",
> >> + sensor_rect->width, sensor_rect->height, width, height,
> >> + mode->sensor_w, mode->sensor_h, mode->max_image_w,
> >> + mode->max_image_h);
> >
> > I wouldn't expect requesting a particular frame rate to change the sensor
> > format. The other way around is definitely fine though.
> >
> > Cc Hans.
>
> I agree with Sakari. Changing the framerate should never change the format.
> When you enumerate framerates those framerates are the allowed framerates
> for the mediabus format and the resolution. So changing the framerate should
> never modify the format or resolution. Instead, the framerate should be
> mapped to a framerate that is valid for the format/resolution combo.
I don't think this is actually documented, at least not for the sub-device
API. I can send a patch.
--
Sakari Ailus
e-mail: sakari.ai...@iki.fi
