drm/panel: panel-simple: Get rid of hacky HPD chicken-and-egg code

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>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.10.I40eeedc23459d1e3fc96fa6cdad775d88c6e706c@changeid

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 9746eda6f675151d2d7b53deb8faa9eb9170630f..bd208abcbf07682c9d2d50d2791c093168a967f2 100644 (file)
--- 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;
        }