Re: [PATCH v3 12/14] drm: bridge/analogix_dp: expand the delay time for hpd detect

[Yakir Yang]

Hi Jingoo,

On 08/20/2015 01:11 AM, Jingoo Han wrote:
> On 2015. 8. 19., at PM 11:52, Yakir Yang <ykk@xxxxxxxxxxxxxx> wrote:
> > Some edp screen with no hpd signal would need some delay time
> > to ensure that screen would be ready for work, so we can expand
> > the delay time in hpd detect function, it works prefectly on my
> > rk3288 sdk board.
> Then, this delay has a dependency on the "rk3288 sdk" board.
> Also, if the delay time is expanded, the booting time of some Exybos boards will be increased unnecessarily. :-(
>
> So, please add new DT property such as 'hpd-delay' that can be added to board DT files.
>
> If there is not that DT property in DT files, the default value '10' will written to a variable such as 'unsigned int hpd_delay'.
> If there is the DT property in DT files, the delay value will written to the variable when parsing DT values
> and will be used in analogix_dp_detect_hpd().
>
> What I want to say is that there should not be harmful effect on the existing Exynos boards, due to unrelated reasons.

Yeah, you are right, I made an mistake here.

And I want to put this delay to "need-force-hpd" code, cause
this property is for the no-hpd-signal eDP screen.

But strangely, with my this series, I don't need the expand delay
any more, I am not sure which change improved this, I guess
those delay time should come from drm core ?

Whatever seems we don't need this delay for now, and if I can
find the exact reason and realize I still need this delay, I prefer
to add those delay in "need-force-hpd" code.

Thanks,
- Yakir
> Best regards,
> Jingoo Han
>
> > Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> > ---
> > Changes in v3: None
> > Changes in v2: None
> >
> > drivers/gpu/drm/bridge/analogix_dp_core.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix_dp_core.c
> > index 99870f7..75dd44a 100644
> > --- a/drivers/gpu/drm/bridge/analogix_dp_core.c
> > +++ b/drivers/gpu/drm/bridge/analogix_dp_core.c
> > @@ -68,7 +68,7 @@ static int analogix_dp_detect_hpd(struct analogix_dp_device *dp)
> >             return 0;
> >
> >         timeout_loop++;
> > -        usleep_range(10, 11);
> > +        usleep_range(100, 110);
> >     }
> >
> >     /*
> > --
> > 1.9.1


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