On 09/18/15 11:43, Arnd Bergmann wrote: > On Friday 18 September 2015 11:27:40 Hans Verkuil wrote: >> Ah, OK. Got it. >> >> I think this is dependent on the upcoming media workshop next month. If we >> decide to redesign v4l2_buffer anyway, then we can avoid timeval completely. >> And the only place where we would need to convert it in the compat code >> hidden in the v4l2 core (likely v4l2-ioctl.c). > > Ah, I think I understood the idea now, I missed that earlier when you mention > the idea. > > So what you are saying here is that you could come up with a new unambiguous > (using only __u32 and __u64 types and no pointers) format that gets exposed > to a new set of ioctls, and then change the handling of the existing three > formats (native 64-bit, traditional 32-bit, and 32-bit with 64-bit time_t) > so they get converted into the new format by the common ioctl handling code? Right. Drivers only see the new struct, and only v4l2-ioctl.c (and possible v4l2-compat-ioctl32.c) see the old ones. BTW, I will probably pick up patches 4 and 6 for 4.4. That should help a bit. Regards, Hans >> I am not really keen on having v4l2_timeval in all these drivers. I would >> have to check them anyway since I suspect that in several drivers the local >> timeval variable can be avoided by rewriting that part of the driver. > > I've tried to do that for all the drivers where I could find an easy solution > in patch 6/9, but I'm sure you can do it for a couple more. > > We could also do a lightweight redesign and use 'timespec64' internally > in all the drivers and then convert that to 'timeval' or the 64-bit > format of that in the ioctl handler. This is also something I tried at > some point but then found it a bit more intuitive to leave the normal ioctl > path alone and have an explicit type. > >> Personally I am in favor of a redesigned v4l2_buffer: it's awkward to use >> with multiplanar formats, there is cruft in there that can be removed (timecode), >> and there is little space for additions (HW-specific timecodes, more buffer >> meta data, etc). >> >> We'll see. > > Ok. > > Arnd > -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
