Hi, On Thu, Jun 2, 2022 at 8:12 AM Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> wrote: > > On 18/04/2022 20:17, 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@xxxxxxxxxxxx> > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > > > --- > > > > (no changes since v2) > > > > Changes in v2: > > - Change is_hpd_asserted() to wait_hpd_asserted() > > > > drivers/gpu/drm/panel/panel-edp.c | 33 +++++++++++++++++++++---------- > > 1 file changed, 23 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c > > index 1732b4f56e38..086e0bf52fb9 100644 > > --- a/drivers/gpu/drm/panel/panel-edp.c > > +++ b/drivers/gpu/drm/panel/panel-edp.c > > @@ -417,6 +417,11 @@ 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->wait_hpd_asserted)); > > +} > > + > > static int panel_edp_prepare_once(struct panel_edp *p) > > { > > struct device *dev = p->base.dev; > > @@ -441,17 +446,21 @@ 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, > > - hpd_asserted, hpd_asserted, > > - 1000, hpd_wait_us); > > - if (hpd_asserted < 0) > > - err = hpd_asserted; > > + if (p->hpd_gpio) { > > + err = readx_poll_timeout(gpiod_get_value_cansleep, > > + p->hpd_gpio, hpd_asserted, > > + hpd_asserted, 1000, hpd_wait_us); > > + if (hpd_asserted < 0) > > + err = hpd_asserted; > > + } else { > > + err = p->aux->wait_hpd_asserted(p->aux, hpd_wait_us); > > + } > > I'm close to thinking that this construct deserves a separate helper. Just to close the loop: I didn't try to create a helper for v5. I'm not completely convinced that this will be common. I would tend to expect that having HPD handled by a GPIO is somewhat rare. It's also fairly rare to have a panel that's not handled by the generic panel-edp. We ended up with the GPIO on trogdor because of the weird debouncing on sn85dsi86 and we ended up with one case of not using edp-panel on trogdor because of the weird power sequencing of the Samsung OLED panel that's on homestar. I'd also note that the generic eDP panel has a special case for "timeout" which we don't have on the Samsung panel to handle at least one panel I found that sometimes simply didn't come up but then _would_ come up on a retry... That doesn't mean we couldn't abstract it out later, of course. ;-) -Doug -Doug