Messages in this thread | | | Date | Mon, 11 Jun 2012 18:46:14 +0800 | Subject | Re: [PATCH 1/3] mx3fb: do not support panning with fb blanked | From | Liu Ying <> |
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2012/6/11, Russell King - ARM Linux <linux@arm.linux.org.uk>: > On Mon, Jun 11, 2012 at 09:06:48AM +0800, Liu Ying wrote: >> This patch checks if framebuffer is unblanked before >> we actually trigger panning in custom pan display >> function. >> >> Signed-off-by: Liu Ying <Ying.Liu@freescale.com> >> --- >> drivers/video/mx3fb.c | 5 +++++ >> 1 files changed, 5 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/video/mx3fb.c b/drivers/video/mx3fb.c >> index e3406ab..d53db60 100644 >> --- a/drivers/video/mx3fb.c >> +++ b/drivers/video/mx3fb.c >> @@ -1063,6 +1063,11 @@ static int mx3fb_pan_display(struct >> fb_var_screeninfo *var, >> dev_dbg(fbi->device, "%s [%c]\n", __func__, >> list_empty(&mx3_fbi->idmac_channel->queue) ? '-' : '+'); >> >> + if (mx3_fbi->blank != FB_BLANK_UNBLANK) { >> + dev_dbg(fbi->device, "panning with fb blanked not supported\n"); >> + return -EFAULT; >> + } > > Why is this an error, and why return -EFAULT? What userspace access > failed? > Hi, Russell,
IMHO, panning with framebuffer blanked is meaningless, at least, it is not a common usecase. Most users use pan display to swap front buffer and back buffer when framebuffer is unblanked/active. So, I choose to take the in question case as an error. Pan display may let user select a buffer address to be active on display and I saw the head file 'errno-base.h' comments EFAULT macro to be 'Bad address', so I use this return value. Perhaps, this return value is not good enough. Maybe, EIO is better? Would you please help to give some advice on this?
Thanks.
-- Best Regards, Liu Ying
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