2012/6/11, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>:
> On Mon, Jun 11, 2012 at 06:46:14PM +0800, Liu Ying wrote:
>> 2012/6/11, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>:
>> > 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@xxxxxxxxxxxxx>
>> >> ---
>> >> 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.
>
> Yes, but why should anything in userspace care whether the display is
> blanked or not?
>
> For example, we may pan the display when a user program produces output,
> and we're on the last line of the display. We don't fail that just
> because the screen happens to be blank. So I don't see why we should
> actively fail an explicit userspace pan request just because the console
> happened to be blanked.
>
> What I'm basically saying is that as far as _userspace_ is concerned,
> all the standard APIs should just work as normal whether the display is
> blanked or not.
>
Ok, understand your point. I am ok to drop this patch.
Thanks.
--
Best Regards,
Liu Ying
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