I don't believe that it ever makes sense to read the EDID when a panel is not powered and the powering on of the panel is the job of prepare(). Let's make sure that this happens before we try to read the EDID. We use the pm_runtime functions directly rather than directly calling the normal prepare() function because the pm_runtime functions are definitely refcounted whereas it's less clear if the prepare() one is.
NOTE: I'm not 100% sure how EDID reading was working for folks in the past, but I can only assume that it was failing on the initial attempt and then working only later. This patch, presumably, will fix that. If some panel out there really can read the EDID without powering up and it's a big advantage to preserve the old behavior we can add a per-panel flag. It appears that providing the DDC bus to the panel in the past was somewhat uncommon in any case.
Signed-off-by: Douglas Anderson dianders@chromium.org Reviewed-by: Bjorn Andersson bjorn.andersson@linaro.org ---
(no changes since v1)
drivers/gpu/drm/panel/panel-simple.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index 4de33c929a59..a12dfe8b8d90 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c @@ -510,12 +510,18 @@ static int panel_simple_get_modes(struct drm_panel *panel,
/* probe EDID if a DDC bus is available */ if (p->ddc) { - struct edid *edid = drm_get_edid(connector, p->ddc); + struct edid *edid;
+ pm_runtime_get_sync(panel->dev); + + edid = drm_get_edid(connector, p->ddc); if (edid) { num += drm_add_edid_modes(connector, edid); kfree(edid); } + + pm_runtime_mark_last_busy(panel->dev); + pm_runtime_put_autosuspend(panel->dev); }
/* add hard-coded panel modes */