2009/7/7 Hans de Goede <hdegoede@xxxxxxxxxx>: > Hi All, > > So recently I've hit 2 issues where kernel side fixes need > to go hand in hand with libv4l updates to not cause regressions. > > First lets discuss the 2 cases: > 1) The pac207 driver currently limits the framerate (and thus > the minimum exposure time) because at higher framerate the > cam starts using a higher compression and we could not > decompress this. Thanks to Bertrik Sikken we can now handle > the higher decompression. > > So no I really want to enable the higher framerates as those > are needed to make the cam work properly in full daylight. > > But if I do this, things will regress for people with an > older libv4l, as that won't be able to decompress the frames > > 2) Several zc3xxx cams have a timing issue between the bridge and > the sensor (the windows drivers have the same issue) which > makes them do only 320x236 instead of 320x240. Currently > we report their resolution to userspace as 320x240, leading to > a bar of noise at the bottom of the screen. > > The fix here obviously is to report the real effective resoltion > to userspace, but this will cause regressions for apps which blindly > assume 320x240 is available (such as skype). The latest libv4l will > make the apps happy again by giving them 320x240 by adding small > black borders. > > > Now I see 2 solutions here: > > a) Just make the changes, seen from the kernel side these are most > certainly bugfixes. I tend towards this for case 2) > > b) Come up with an API to tell the libv4l version to the kernel and > make these changes in the drivers conditional on the libv4l version > > Solution b) sounds messy and will probably lead to a lot of error prone glue code in the kernel. Fast-forward a couple of libv4l releases and you will have a nightmare maintainability scenario. If people run an old libv4l with a new kernel and run into problem, just tell them to upgrade their libv4l version. My 2 cents, Erik > So this is my dilemma, your input is greatly appreciated. > > Regards, > > Hans > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
