Re: [PATCH] Implement changing resolution on the fly for zr364xx driver
Lamarque Vieira Souza <[email protected]>
| Newsgroups | gmane.linux.drivers.video-input-infrastructure,gmane.comp.video.video4linux |
|---|---|
| Message-ID | <[email protected]> |
Em Terça-feira 21 Julho 2009, Antoine Jacquet escreveu: > Hi, Hi, > > This patch implements changing resolution in zr364xx_vidioc_s_fmt_vid_cap > > for zr364xx driver. This version is synced with v4l-dvb as of > > 20/Jul/2009. Tested with Creative PC-CAM 880. > > Nice, I successfully tested your patch with 2 compatible webcams. > From the users feedbacks I had before, it seems that some devices do > not support the 640x480 resolution, but I was not able to verify this > myself. > This is the only concern I have, since some users may think the driver > is not working if the application automatically switches to the maximum > resolution with an incompatible device. Maybe we should add a quirk list to prevent such cases or if send_control_msg returns error in such cases I can change the code to revert the change and keep the old resolution. > > OBS: I had to increase MAX_FRAME_SIZE to prevent a hard crash in my > > notebook (caps lock blinking) when testing with mplayer, which > > automatically sets resolution to the maximum (640x480). Maybe we should > > add code to auto-detect frame size to prevent this kind of crash in the > > future. > > Yes, I also had this issue before. I don't know what is the good > approach to determine the best size with JPEG compression. The driver reads data from USB port in 4096-bytes chunks, so before adding the data to frm->lpvbits we could verify if frm->lpvbits has enough space to hold it. If there is no enough space we can dynamically increase frm->lpvbits. In user space that can be done using realloc, I just do not know if there is a similar function in kernel space. OBS: frm->lpvbits had be increased without loosing the old data and of course we should have a upper limit, maybe 640 x 480 * 3 (3 bytes per pixel) = 921600 bytes. > I will push your changes to my tree and send a pull request to Mauro later. Ok, thanks. -- Lamarque V. Souza http://www.geographicguide.com/brazil.htm Linux User #57137 - http://counter.li.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html