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",