On Fri, Feb 12, 2010 at 4:18 PM, Ian Armstrong <mail01@xxxxxxxxxxxx> wrote: > > I would question the original definition for FBIO_WAITFORVSYNC. I get the > impression that it originated with the matrox driver, but other drivers have > since implemented the same ioctl and each has an identical define. Would the > proper fix be to get the definition into fb.h and use it from there. It's > already defined in multiple places (ps3fb.h, intelfb.h, atyfb_base.c, > ivtvfb.h, matroxfb.h) and exported to userspace more than once. > Hi Ian, fbdev folks, Yes, I think the fbdev and vsync concept needs an update. I have an API I would like to propose. It is still early and I would like to make it sufficiently generic so that it can meet the needs of at least the following types of hardware: A- those that expose a vertical retrace counter B- those that support generating an interrupt at the start of the vertical blanking period C- those controllers for displays that do not have a concept of vertical retrace (ie: non-volatile/bistable displays) The api would look like (from userspace): fb_wait_vsync(int div, int rem, unsigned int *count); Internally, that would lead to an ioctl and drivers would be able to provide an fbops for their specific implementation. The implementation would do something along the following lines for each hardware type: A- put the calling process to sleep until (retrace_counter % div == rem). This will let vissim apps achieve their desired level of granularity. B- put the calling process to sleep until the vblank interrupt is received plus calculated offset using timing and pixclock, returning the calculated value for the count. C- put the calling process to sleep until the most recent display update is completed, returning 0 for the count and ignoring div, rem. Let me know if this concept looks satisfactory. Thanks, jaya -- 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
