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Message-ID: <20241126134019.GG5461@pendragon.ideasonboard.com> Date: Tue, 26 Nov 2024 15:40:19 +0200 From: Laurent Pinchart <laurent.pinchart@...asonboard.com> To: Dave Stevenson <dave.stevenson@...pberrypi.com> Cc: Jai Luthra <jai.luthra@...asonboard.com>, Sakari Ailus <sakari.ailus@...ux.intel.com>, Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, Jacopo Mondi <jacopo.mondi@...asonboard.com> Subject: Re: [PATCH v3 2/3] media: i2c: imx219: make HBLANK r/w to allow longer exposures Hi Dave, On Tue, Nov 26, 2024 at 01:21:27PM +0000, Dave Stevenson wrote: > On Tue, 26 Nov 2024 at 12:16, Laurent Pinchart wrote: > > On Mon, Nov 25, 2024 at 08:36:26PM +0530, Jai Luthra wrote: > > > From: Dave Stevenson <dave.stevenson@...pberrypi.com> > > > > > > The HBLANK control was read-only, and always configured such > > > that the sensor HTS register was 3448. This limited the maximum > > > exposure time that could be achieved to around 1.26 secs. > > > > > > Make HBLANK read/write so that the line time can be extended, > > > and thereby allow longer exposures (and slower frame rates). > > > Retain the overall HTS setting when changing modes rather than > > > resetting it to a default. > > > > > > Signed-off-by: Dave Stevenson <dave.stevenson@...pberrypi.com> > > > Reviewed-by: Jacopo Mondi <jacopo.mondi@...asonboard.com> > > > Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com> > > > --- > > > drivers/media/i2c/imx219.c | 37 ++++++++++++++++++++++++------------- > > > 1 file changed, 24 insertions(+), 13 deletions(-) > > > > > > diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c > > > index f98aad74fe584a18e2fe7126f92bf294762a54e3..970e6362d0ae3a9078daf337155e83d637bc1ca1 100644 > > > --- a/drivers/media/i2c/imx219.c > > > +++ b/drivers/media/i2c/imx219.c > > > @@ -76,8 +76,10 @@ > > > > > > #define IMX219_VBLANK_MIN 32 > > > > > > -/* HBLANK control - read only */ > > > -#define IMX219_PPL_DEFAULT 3448 > > > +/* HBLANK control range */ > > > > Just drop the comment, and drop the blank lines, this belongs to the > > "V_TIMING internal" section. > > > > > +#define IMX219_PPL_MIN 0x0d78 > > > > Why PPL and not HTS ? > > The IMX219 datasheet defines the register as LINE_LENGTH_A, with > comment line_length_pck. > > HTS is not a term used in the imx219 datasheet, so why introduce it to > the driver? I'd go along with a rename to LLP if you wish. > (HTS is more commonly an Omnivision term, not a Sony one). I thought the datasheet used HTS, my bad. Now that you mention it, HTS is indeed more of an OmniVision term. Sorry for the oversight. I would then name the macro IMX219_REG_LINE_LENGTH, and rename IMX219_REG_VTS to IMX219_REG_FRM_LENGTH. > > > +#define IMX219_PPL_MAX 0x7ff0 > > > +#define IMX219_REG_HTS CCI_REG16(0x0162) > > > > The min/max should go below the register definition. > > > > > > > > #define IMX219_REG_LINE_LENGTH_A CCI_REG16(0x0162) > > > #define IMX219_REG_X_ADD_STA_A CCI_REG16(0x0164) > > > @@ -422,6 +424,10 @@ static int imx219_set_ctrl(struct v4l2_ctrl *ctrl) > > > cci_write(imx219->regmap, IMX219_REG_VTS, > > > format->height + ctrl->val, &ret); > > > break; > > > + case V4L2_CID_HBLANK: > > > + cci_write(imx219->regmap, IMX219_REG_HTS, > > > + format->width + ctrl->val, &ret); > > > + break; > > > case V4L2_CID_TEST_PATTERN_RED: > > > cci_write(imx219->regmap, IMX219_REG_TESTP_RED, > > > ctrl->val, &ret); > > > @@ -496,12 +502,10 @@ static int imx219_init_controls(struct imx219 *imx219) > > > V4L2_CID_VBLANK, IMX219_VBLANK_MIN, > > > IMX219_VTS_MAX - mode->height, 1, > > > mode->vts_def - mode->height); > > > - hblank = IMX219_PPL_DEFAULT - mode->width; > > > + hblank = IMX219_PPL_MIN - mode->width; > > > imx219->hblank = v4l2_ctrl_new_std(ctrl_hdlr, &imx219_ctrl_ops, > > > V4L2_CID_HBLANK, hblank, hblank, > > > > The minimum and maximum are identical, is this intentional ? > > The limits should be updated when the format is set, so the values > shouldn't matter when created. However I'd want to check that did > happen seeing as vblank computes the limits here. > It is as easy to set them correctly here too (max = IMX219_PPL_MAX - > mode->width), so you may as well. I would at least handle hblank and vblank the same way. If we expect the values to be updated, a comment to indicate so would be good. The current code states /* Initial vblank/hblank/exposure parameters based on current mode */ > > > 1, hblank); > > > - if (imx219->hblank) > > > - imx219->hblank->flags |= V4L2_CTRL_FLAG_READ_ONLY; > > > exposure_max = mode->vts_def - 4; > > > exposure_def = (exposure_max < IMX219_EXPOSURE_DEFAULT) ? > > > exposure_max : IMX219_EXPOSURE_DEFAULT; > > > @@ -817,6 +821,10 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd, > > > struct v4l2_mbus_framefmt *format; > > > struct v4l2_rect *crop; > > > unsigned int bin_h, bin_v; > > > + u32 prev_hts; > > > + > > > + format = v4l2_subdev_state_get_format(state, 0); > > > + prev_hts = format->width + imx219->hblank->val; > > > > > > mode = v4l2_find_nearest_size(supported_modes, > > > ARRAY_SIZE(supported_modes), > > > @@ -824,8 +832,6 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd, > > > fmt->format.width, fmt->format.height); > > > > > > imx219_update_pad_format(imx219, mode, &fmt->format, fmt->format.code); > > > - > > > - format = v4l2_subdev_state_get_format(state, 0); > > > *format = fmt->format; > > > > > > /* > > > @@ -861,13 +867,18 @@ static int imx219_set_pad_format(struct v4l2_subdev *sd, > > > exposure_max, imx219->exposure->step, > > > exposure_def); > > > /* > > > - * Currently PPL is fixed to IMX219_PPL_DEFAULT, so hblank > > > - * depends on mode->width only, and is not changeble in any > > > - * way other than changing the mode. > > > + * Retain PPL setting from previous mode so that the > > > > Rename PPL to HTS here too. > > Disagree as above. The local variable here should be renamed prev_ppl > or prev_llp. Or prev_line_length. I agree that hts isn't a good name here. > > > + * line time does not change on a mode change. > > > + * Limits have to be recomputed as the controls define > > > + * the blanking only, so PPL values need to have the > > > + * mode width subtracted. > > > */ > > > - hblank = IMX219_PPL_DEFAULT - mode->width; > > > - __v4l2_ctrl_modify_range(imx219->hblank, hblank, hblank, 1, > > > - hblank); > > > + hblank = prev_hts - mode->width; > > > + __v4l2_ctrl_modify_range(imx219->hblank, > > > + IMX219_PPL_MIN - mode->width, > > > + IMX219_PPL_MAX - mode->width, > > > + 1, IMX219_PPL_MIN - mode->width); > > > + __v4l2_ctrl_s_ctrl(imx219->hblank, hblank); > > > } > > > > > > return 0; -- Regards, Laurent Pinchart
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