Hi Dave, On Mon, Nov 11, 2024 at 07:37:56PM +0000, Dave Stevenson wrote: > Hi Sakari > > On Fri, 8 Nov 2024 at 10:30, Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > Hi Dave, > > > > On Thu, Nov 07, 2024 at 12:43:52PM +0000, Dave Stevenson wrote: > > > Hi Sakari > > > > > > On Fri, 1 Nov 2024 at 08:48, Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote: > > > > > > > > Hi Jai, > > > > > > > > On Tue, Oct 29, 2024 at 02:27:36PM +0530, Jai Luthra wrote: > > > > > From: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx> > > > > > > > > > > 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. > > > > > > > > It looks like this changes horizontal blanking at least in some cases. Does > > > > this also work as expected in binned modes, for instance? > > > > > > > > Many sensors have image quality related issues on untested albeit > > > > functional line length values. > > > > > > > > So my question is: how has this been validated? > > > > > > Validated by Sony, or others? > > > I've tested a range of values in all modes and not observed any image > > > quality issues. > > > > Somehow at least. :-) > > > > > > > > From previous discussions with Sony, they always provide their big > > > spreadsheet of register values for the specific mode and frame rate > > > requested. I don't think they even officially state that changing > > > VTS/FRM_LENGTH_LINES to change the framerate is permitted. > > > There are some Sony datasheets (eg imx258) that state "set to X. Any > > > other value please confirm with Sony", but that isn't the case for the > > > imx219 datasheet. I take that as it is permitted within the defined > > > ranges. > > > > I'm not that much concerned of vertical blanking, changing that within the > > valid range has effects on the image itself very seldom. Horizontal > > blanking is different though and this is what the patch makes changeable, > > including a change in the default value. Of course there are big > > differences between sensors here. > > The intention was that the default value shouldn't change, and as the > overall PIXELS_PER_LINE value was meant to be retained on a mode > change the value used should only change if an application changes > V4L2_CID_HBLANK. If I blundered in the implementation of that, then > that should be fixed (I know Jacopo made comments, but I haven't had a > chance to investigate). I guess I misread the patch. It indeed should be the same. > > I doubt we'd get validation from Sony beyond the contents of the > datasheet. Potentially as the sensor is so old they don't have the > information or engineers involved. > I'm happy to set up a test system and capture a set of images with > HBLANK from min to max at some increment. With the same exposure and > gain they should all be identical as long as there isn't any movement > (rolling shutter with longer readout times and all that). Would that > be satisfactory? Sounds good to me. I just thought how it actually had been tested. :-) > > For contrast, the IMX290 datasheet states that VMAX shall be fixed at > 0x465 for all-pixel mode / 0x2ee for 720p mode, and HMAX should be > changed for frame rate control. As you say, sensors differ. -- Kind regards, Sakari Ailus
