Messages in this thread | | | Date | Sat, 16 Apr 2022 03:14:42 +0300 | Subject | Re: [RFC PATCH 4/6] drm/panel-edp: Take advantage of is_hpd_asserted() in struct drm_dp_aux | From | Dmitry Baryshkov <> |
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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.
-- With best wishes Dmitry
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