From: Doug Anderson <dianders@chromium.org>
To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
Robert Foss <robert.foss@linaro.org>,
Hsin-Yi Wang <hsinyi@chromium.org>,
Abhinav Kumar <quic_abhinavk@quicinc.com>,
Sankeerth Billakanti <quic_sbillaka@quicinc.com>,
Philip Chen <philipchen@chromium.org>,
Stephen Boyd <swboyd@chromium.org>,
Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
Sam Ravnborg <sam@ravnborg.org>,
Thierry Reding <thierry.reding@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 4/6] drm/panel-edp: Take advantage of is_hpd_asserted() in struct drm_dp_aux
Date: Mon, 18 Apr 2022 10:18:54 -0700 [thread overview]
Message-ID: <CAD=FV=VP+tcrCwBQeF+QTBcsTraZVzxQqnAKBQQ_Hb6CyUQ0BA@mail.gmail.com> (raw)
In-Reply-To: <835fa3cd-0777-1dea-972f-3e24d5aeda3a@linaro.org>
Hi,
On Fri, Apr 15, 2022 at 5:14 PM Dmitry Baryshkov
<dmitry.baryshkov@linaro.org> wrote:
>
> On 16/04/2022 03:12, Doug Anderson wrote:
> > Hi,
> >
> > On Fri, Apr 15, 2022 at 3:12 PM Dmitry Baryshkov
> > <dmitry.baryshkov@linaro.org> wrote:
> >>
> >> On Sat, 16 Apr 2022 at 00:17, Doug Anderson <dianders@chromium.org> wrote:
> >>>
> >>> Hi,
> >>>
> >>> On Thu, Apr 14, 2022 at 5:51 PM Dmitry Baryshkov
> >>> <dmitry.baryshkov@linaro.org> wrote:
> >>>>
> >>>> On 09/04/2022 05:36, Douglas Anderson wrote:
> >>>>> Let's add support for being able to read the HPD pin even if it's
> >>>>> hooked directly to the controller. This will allow us to get more
> >>>>> accurate delays also lets us take away the waiting in the AUX transfer
> >>>>> functions of the eDP controller drivers.
> >>>>>
> >>>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> >>>>> ---
> >>>>>
> >>>>> drivers/gpu/drm/panel/panel-edp.c | 37 ++++++++++++++++++++++++++-----
> >>>>> 1 file changed, 31 insertions(+), 6 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c
> >>>>> index 1732b4f56e38..4a143eb9544b 100644
> >>>>> --- a/drivers/gpu/drm/panel/panel-edp.c
> >>>>> +++ b/drivers/gpu/drm/panel/panel-edp.c
> >>>>> @@ -417,6 +417,19 @@ static int panel_edp_get_hpd_gpio(struct device *dev, struct panel_edp *p)
> >>>>> return 0;
> >>>>> }
> >>>>>
> >>>>> +static bool panel_edp_can_read_hpd(struct panel_edp *p)
> >>>>> +{
> >>>>> + return !p->no_hpd && (p->hpd_gpio || (p->aux && p->aux->is_hpd_asserted));
> >>>>> +}
> >>>>> +
> >>>>> +static bool panel_edp_read_hpd(struct panel_edp *p)
> >>>>> +{
> >>>>> + if (p->hpd_gpio)
> >>>>> + return gpiod_get_value_cansleep(p->hpd_gpio);
> >>>>> +
> >>>>> + return p->aux->is_hpd_asserted(p->aux);
> >>>>> +}
> >>>>> +
> >>>>> static int panel_edp_prepare_once(struct panel_edp *p)
> >>>>> {
> >>>>> struct device *dev = p->base.dev;
> >>>>> @@ -441,13 +454,21 @@ static int panel_edp_prepare_once(struct panel_edp *p)
> >>>>> if (delay)
> >>>>> msleep(delay);
> >>>>>
> >>>>> - if (p->hpd_gpio) {
> >>>>> + if (panel_edp_can_read_hpd(p)) {
> >>>>> if (p->desc->delay.hpd_absent)
> >>>>> hpd_wait_us = p->desc->delay.hpd_absent * 1000UL;
> >>>>> else
> >>>>> hpd_wait_us = 2000000;
> >>>>>
> >>>>> - err = readx_poll_timeout(gpiod_get_value_cansleep, p->hpd_gpio,
> >>>>> + /*
> >>>>> + * Extra max delay, mostly to account for ps8640. ps8640
> >>>>> + * is crazy and the bridge chip driver itself has over 200 ms
> >>>>> + * of delay if it needs to do the pm_runtime resume of the
> >>>>> + * bridge chip to read the HPD.
> >>>>> + */
> >>>>> + hpd_wait_us += 3000000;
> >>>>
> >>>> I think this should come in a separate commit and ideally this should be
> >>>> configurable somehow. Other hosts wouldn't need such 'additional' delay.
> >>>>
> >>>> With this change removed:
> >>>>
> >>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> >>>
> >>> What would you think about changing the API slightly? Instead of
> >>> is_hpd_asserted(), we change it to wait_hpd_asserted() and it takes a
> >>> timeout in microseconds. If you pass 0 for the timeout the function is
> >>> defined to behave the same as is_hpd_asserted() today--AKA a single
> >>> poll of the line.
> >>
> >> This might work. Can you check it, please?
> >
> > Cool. I'll spin with this. Hopefully early next week unless my inbox
> > blows up. ...or my main PC's SSD like happened this week. ;-)
> >
> >
> >> BTW: are these changes dependent on the first part of the patchset? It
> >> might be worth splitting the patchset into two parts.
> >
> > Definitely not. As per the cover letter, this is two series jammed
> > into one. I'm happy to split them up. The 2nd half seems much less
> > controversial.
>
> Great, let's get it in then. As you have time.
Breadcrumbs: I've posted this as:
https://lore.kernel.org/r/20220418171757.2282651-1-dianders@chromium.org
-Doug
next prev parent reply other threads:[~2022-04-18 17:19 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-09 2:36 [RFC PATCH 0/6] drm/dp: Improvements for DP AUX channel Douglas Anderson
2022-04-09 2:36 ` [RFC PATCH 1/6] drm/dp: Helpers to make it easier for drivers to use DP AUX bus properly Douglas Anderson
2022-04-11 8:34 ` Jani Nikula
2022-04-11 13:37 ` Doug Anderson
2022-04-14 23:51 ` Stephen Boyd
2022-04-15 21:13 ` Doug Anderson
2022-04-15 0:46 ` Dmitry Baryshkov
2022-04-15 21:13 ` Doug Anderson
2022-04-15 22:44 ` Dmitry Baryshkov
2022-04-16 0:09 ` Doug Anderson
2022-04-16 0:54 ` Dmitry Baryshkov
2022-04-18 23:10 ` Doug Anderson
2022-05-03 22:45 ` Doug Anderson
2022-05-03 23:23 ` Doug Anderson
2022-04-09 2:36 ` [RFC PATCH 2/6] drm/bridge: parade-ps8640: Break probe in two to handle DP AUX better Douglas Anderson
2022-04-09 2:36 ` [RFC PATCH 3/6] drm/dp: Add is_hpd_asserted() callback to struct drm_dp_aux Douglas Anderson
2022-04-15 0:48 ` Dmitry Baryshkov
2022-04-09 2:36 ` [RFC PATCH 4/6] drm/panel-edp: Take advantage of is_hpd_asserted() in " Douglas Anderson
2022-04-15 0:51 ` Dmitry Baryshkov
2022-04-15 21:17 ` Doug Anderson
2022-04-15 22:11 ` Dmitry Baryshkov
2022-04-16 0:12 ` Doug Anderson
2022-04-16 0:14 ` Dmitry Baryshkov
2022-04-18 17:18 ` Doug Anderson [this message]
2022-04-09 2:36 ` [RFC PATCH 5/6] drm/panel: atna33xc20: " Douglas Anderson
2022-04-09 2:36 ` [RFC PATCH 6/6] drm/bridge: parade-ps8640: Provide " Douglas Anderson
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