hi Umang, On Wed, Oct 18, 2023 at 06:47:29PM +0530, Umang Jain wrote: > According to MIPI CCS v1.1 specification, the LINE_LENGTH_PCK > units is in VT pixel clocks (Section 8.2.6). > > To compute how many pixel clocks it takes, simply divide the > VT pixel clock frequency by the number of pixels in a single line. > > Signed-off-by: Umang Jain <umang.jain@xxxxxxxxxxxxxxxx> > --- > Testing: > > The patch is tested using IMX519 with CCS. > This patch makes the frame buffer being filled to the fullest > (instead of getting 1/3rd only previously) - without any workarounds. > --- > drivers/media/i2c/ccs/ccs-core.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/i2c/ccs/ccs-core.c b/drivers/media/i2c/ccs/ccs-core.c > index 16de66a37fad..12c75a843dfe 100644 > --- a/drivers/media/i2c/ccs/ccs-core.c > +++ b/drivers/media/i2c/ccs/ccs-core.c > @@ -734,9 +734,11 @@ static int ccs_set_ctrl(struct v4l2_ctrl *ctrl) > > break; > case V4L2_CID_HBLANK: > - rval = ccs_write(sensor, LINE_LENGTH_PCK, > - sensor->pixel_array->crop[CCS_PA_PAD_SRC].width > - + ctrl->val); > + /* LINE_LENGTH_PCK units are in VT pixel clocks. */ > + u16 line_length_pck = > + sensor->pll.vt_bk.pix_clk_freq_hz / > + (sensor->pixel_array->crop[CCS_PA_PAD_SRC].width + ctrl->val); The time of processing one pixel in the pixel array takes a single VT pixel clock. This register configures how many you have per line, i.e. analogue crop width + horizontal blanking --- which is what the driver does without this patch. I'm still not suggesting the default value for LINE_LENGTH_PCK CCS driver programs is correct value for this device. The issue is still almost certainly in the related limit register values in the sensor's register address space, and that should be addressed by using CCS static data. > + rval = ccs_write(sensor, LINE_LENGTH_PCK, line_length_pck); > > break; > case V4L2_CID_TEST_PATTERN: -- Regards, Sakari Ailus
