[PATCH v4 16/27] drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code

Douglas Anderson
2021-04-16T22:41:57Z

When I added support for the hpd-gpio to simple-panel in commit
48834e6084f1 ("drm/panel-simple: Support hpd-gpios for delaying
prepare()"), I added a special case to handle a circular dependency I
was running into on the ti-sn65dsi86 bridge chip. On my board the
hpd-gpio is actually provided by the bridge chip. That was causing
some circular dependency problems that I had to work around by getting
the hpd-gpio late.

I've now reorganized the ti-sn65dsi86 bridge chip driver to be a
collection of sub-drivers. Now the GPIO part can probe separately and
that breaks the chain. Let's get rid of the old code to clean things
up.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

(no changes since v1)

drivers/gpu/drm/panel/panel-simple.c | 24 +++++-------------------
1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 6b22872b3281..90a17ca79d06 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -366,8 +366,7 @@ static int panel_simple_unprepare(struct drm_panel *panel)
return 0;
}

-static int panel_simple_get_hpd_gpio(struct device *dev,
- struct panel_simple *p, bool from_probe)
+static int panel_simple_get_hpd_gpio(struct device *dev, struct panel_simple *p)
{
int err;

@@ -375,17 +374,10 @@ static int panel_simple_get_hpd_gpio(struct device *dev,
if (IS_ERR(p->hpd_gpio)) {
err = PTR_ERR(p->hpd_gpio);

- /*
- * If we're called from probe we won't consider '-EPROBE_DEFER'
- * to be an error--we'll leave the error code in "hpd_gpio".
- * When we try to use it we'll try again. This allows for
- * circular dependencies where the component providing the
- * hpd gpio needs the panel to init before probing.
- */
- if (err != -EPROBE_DEFER || !from_probe) {
+ if (err != -EPROBE_DEFER)
dev_err(dev, "failed to get 'hpd' GPIO: %d\n", err);
- return err;
- }
+
+ return err;
}

return 0;
@@ -416,12 +408,6 @@ static int panel_simple_prepare_once(struct panel_simple *p)
msleep(delay);

if (p->hpd_gpio) {
- if (IS_ERR(p->hpd_gpio)) {
- err = panel_simple_get_hpd_gpio(dev, p, false);
- if (err)
- goto error;
- }
-
if (p->desc->delay.hpd_absent_delay)
hpd_wait_us = p->desc->delay.hpd_absent_delay * 1000UL;
else
@@ -682,7 +668,7 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)

panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
if (!panel->no_hpd) {
- err = panel_simple_get_hpd_gpio(dev, panel, true);
+ err = panel_simple_get_hpd_gpio(dev, panel);
if (err)
return err;
}
--
2.31.1.368.gbe11c130af-goog