On 11/02/14 21:07, Ryan Mallon wrote: > On 12/02/14 03:06, Tomi Valkeinen wrote: > >> On 20/09/13 10:06, Ryan Mallon wrote: >>> Several video drivers open code the fb_write write function with code >>> which is very similar to fb_sys_write. Replace the open code versions >>> with calls to fb_sys_write. An fb_sync callback is added to each of >>> the drivers. >>> >>> Signed-off-by: Ryan Mallon <rmallon@xxxxxxxxx> >>> --- >> >> Doesn't this change the behavior so that fb_write does no longer update >> the display, but fb_sync does? I don't think fb_sync is even meant to >> update the display, it's meant to wait for an update to finish. Then >> again, I'm not sure about that, all I see in fb.h is "wait for blit >> idle, optional" > > > fb_write() in fbmem.c calls ->fb_sync() after ->fb_write(), and I've set > the fb_sync() for each of the drivers, so the behaviour should be > unchanged for writes. > > The fb_sync() function is also called by fb_read() and > fb_get_buffer_offset() (if FB_PIXMAP_SYNC flag is set). I don't know if > that will adversely affect behaviour. Well, by just looking at the function names the drivers' fb_syncs call, it sounds to me that with your patch fb_sync will update the LCD, i.e. send data to it. Doing that in fb_read sounds totally wrong. > Note that I haven't actually tested this code since I don't have any of > the hardware. It was just something I noticed while digging through > framebuffer driver code. Ok. Well, I think it's safer to drop these, then, if it's not 100% clear that there are no unwanted side effects. Tomi
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