[PATCH 2/3] clk: qcom: gdsc: propagate gdsc_enable() failure for ALWAYS_ON domains

[Herman van Hazendonk]

GENPD_FLAG_ALWAYS_ON requires the underlying domain to be on at
genpd_init() time -- the framework will refuse to register the domain
otherwise. When the cold readback in gdsc_init() finds an ALWAYS_ON
GDSC powered down, the driver tries to bring it back up:

	} else if (sc->flags & ALWAYS_ON) {
		/* If ALWAYS_ON GDSCs are not ON, turn them ON */
		gdsc_enable(&sc->pd);
		on = true;
	}

but discards the return value: if gdsc_enable() fails (regmap write
error, the long-form sequence's status poll times out, or the
HW_CTRL hand-off errors) the code still sets on=true and falls
through to pm_genpd_init(..., !on) -- which then registers the
domain in the ON state and sets GENPD_FLAG_ALWAYS_ON, even though
the silicon is actually off. Subsequent consumer probes will see
genpd report "on" while accessing dead registers and hang or read
garbage.

Catch the failure and surface it: returning the error from
gdsc_init() makes the provider probe fail with the underlying errno,
which propagates to consumers as -EPROBE_DEFER (or fatal if the
hardware really is broken) rather than silently lying about the
rail state.

Signed-off-by: Herman van Hazendonk <github.com@xxxxxxxxxx>
---
 drivers/clk/qcom/gdsc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index b9b47f584f6d..a80a489763ed 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -481,7 +481,9 @@ static int gdsc_init(struct gdsc *sc)
 
 	} else if (sc->flags & ALWAYS_ON) {
 		/* If ALWAYS_ON GDSCs are not ON, turn them ON */
-		gdsc_enable(&sc->pd);
+		ret = gdsc_enable(&sc->pd);
+		if (ret)
+			return ret;
 		on = true;
 	}
 
-- 
2.43.0