[PATCH AUTOSEL 6.17-5.15] clk: ti: am33xx: keep WKUP_DEBUGSS_CLKCTRL enabled

[PATCH AUTOSEL 6.17-5.15] clk: ti: am33xx: keep WKUP_DEBUGSS_CLKCTRL enabled

[Sasha Levin]

From: Matthias Schiffer <matthias.schiffer@tq-group.com>

[ Upstream commit 1e0d75258bd09323cb452655549e03975992b29e ]

As described in AM335x Errata Advisory 1.0.42, WKUP_DEBUGSS_CLKCTRL
can't be disabled - the clock module will just be stuck in transitioning
state forever, resulting in the following warning message after the wait
loop times out:

    l3-aon-clkctrl:0000:0: failed to disable

Just add the clock to enable_init_clks, so no attempt is made to disable
it.

Signed-off-by: Matthias Schiffer <matthias.schiffer@tq-group.com>
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

YES: The change simply marks WKUP_DEBUGSS as an always-on clock so the
driver no longer violates the AM335x erratum.

- `drivers/clk/ti/clk-33xx.c:261` now lists `l3-aon-clkctrl:0000:0` in
  `enable_init_clks`, explicitly keeping WKUP_DEBUGSS enabled as
  mandated by Errata Advisory 1.0.42; without this, the init sequence
  still tries to gate the module and hits the hardware deadlock
  described in the advisory.
- Today the disable path waits for the module to idle, times out, and
  prints `l3-aon-clkctrl:0000:0: failed to disable`
  (`drivers/clk/ti/clkctrl.c:194`), so every boot (and any later
  clk_disable_unused run) produces user-visible errors while leaving the
  clock stuck in “transitioning”; the patch stops that erroneous
  transition request entirely.
- Effect scope is tiny: one entry in an SoC-specific static list,
  matching how other errata workarounds (e.g. `l3-clkctrl:00bc:0`) are
  handled; the hardware already refuses to power down the block, so
  forcing it on introduces no new behaviour or power regression.
- No API or structural change, only affects AM33xx clock init, and it
  backports cleanly to older kernels using the same
  `omap2_clk_enable_init_clocks()` helper.

Suggested follow-up once backported: boot an AM335x board with
`clk_ignore_unused` removed to confirm the “failed to disable” warning
is gone.

 drivers/clk/ti/clk-33xx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clk/ti/clk-33xx.c b/drivers/clk/ti/clk-33xx.c
index 85c50ea39e6da..9269e6a0db6a4 100644
--- a/drivers/clk/ti/clk-33xx.c
+++ b/drivers/clk/ti/clk-33xx.c
@@ -258,6 +258,8 @@ static const char *enable_init_clks[] = {
 	"dpll_ddr_m2_ck",
 	"dpll_mpu_m2_ck",
 	"l3_gclk",
+	/* WKUP_DEBUGSS_CLKCTRL - disable fails, AM335x Errata Advisory 1.0.42 */
+	"l3-aon-clkctrl:0000:0",
 	/* AM3_L3_L3_MAIN_CLKCTRL, needed during suspend */
 	"l3-clkctrl:00bc:0",
 	"l4hs_gclk",
-- 
2.51.0