Hi Geert, Thanks for the feedback. On Sunday 31 July 2011 22:32:42 Geert Uytterhoeven wrote: > On Thu, Jul 28, 2011 at 12:51, Laurent Pinchart wrote: > >> As for struct fb_var_screeninfo fields to support switching to a FOURCC > >> mode, I also prefer an explicit dedicated flag to specify switching to > >> it. Even though using FOURCC doesn't fit under the notion of a > >> videomode, using one of .vmode bits is too tempting, so, I would > >> actually take the plunge and use FB_VMODE_FOURCC. > > > > Another option would be to consider any grayscale > 1 value as a FOURCC. > > I've briefly checked the in-tree drivers: they only assign grayscale > > with 0 or 1, and check whether grayscale is 0 or different than 0. If a > > userspace application only sets grayscale > 1 when talking to a driver > > that supports the FOURCC-based API, we could get rid of the flag. > > > > What can't be easily found out is whether existing applications set > > grayscale to a > 1 value. They would break when used with FOURCC-aware > > drivers if we consider any grayscale > 1 value as a FOURCC. Is that a > > risk we can take ? > > I think we can. I'd expect applications to use either 1 or -1 (i.e. all > ones), both are invalid FOURCC values. OK. > Still, I prefer the nonstd way. > And limiting traditional nonstd values to the lowest 24 bits (there > are no in-tree drivers using the highest 8 bits, right?). None that I've found. I still have a preference for the grayscale field though. As mentioned by Guennadi, the grayscale field would become redundant for FOURCC-based formats. It's then a good candidate, and would let drivers (and applications) do any crazy stuff they want with the nonstd field. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
