While cleaning up the descriptions of the delay for eDP panels I realized that we'd have a bug if any panels need the "prepare_to_enable" but HPD handling isn't happening in the panel driver. Let's put in a stopgap to at least make us not violate timings. This is not perfectly optimal but trying to do better is hard. At the moment only 2 panels specify this delay and only 30 ms is at stake. These panels are also currently hooked up with "hpd-gpios" so effectively this "fix" is just a theoretical fix and won't actually do anything for any devices currently supported in mainline.
Signed-off-by: Douglas Anderson dianders@chromium.org Acked-by: Sam Ravnborg sam@ravnborg.org ---
(no changes since v4)
Changes in v4: - panel-simple-edp => panel-edp
Changes in v3: - Fix "prepare_to_enable" patch new for v3.
drivers/gpu/drm/panel/panel-edp.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/panel/panel-edp.c b/drivers/gpu/drm/panel/panel-edp.c index 80a37a4e5750..a83ef9905ea7 100644 --- a/drivers/gpu/drm/panel/panel-edp.c +++ b/drivers/gpu/drm/panel/panel-edp.c @@ -508,12 +508,32 @@ static int panel_edp_prepare(struct drm_panel *panel) static int panel_edp_enable(struct drm_panel *panel) { struct panel_edp *p = to_panel_edp(panel); + unsigned int delay;
if (p->enabled) return 0;
- if (p->desc->delay.enable) - msleep(p->desc->delay.enable); + delay = p->desc->delay.enable; + + /* + * If there is a "prepare_to_enable" delay then that's supposed to be + * the delay from HPD going high until we can turn the backlight on. + * However, we can only count this if HPD is handled by the panel + * driver, not if it goes to a dedicated pin on the controller. + * If we aren't handling the HPD pin ourselves then the best we + * can do is assume that HPD went high immediately before we were + * called (and link training took zero time). + * + * NOTE: if we ever end up in this "if" statement then we're + * guaranteed that the panel_edp_wait() call below will do no delay. + * It already handles that case, though, so we don't need any special + * code for it. + */ + if (p->desc->delay.prepare_to_enable && !p->hpd_gpio && !p->no_hpd) + delay = max(delay, p->desc->delay.prepare_to_enable); + + if (delay) + msleep(delay);
panel_edp_wait(p->prepared_time, p->desc->delay.prepare_to_enable);