From: Stephen Boyd sboyd@kernel.org
[ Upstream commit fda48bf5c86d88fd7074e318f290ad636dff4eaa ]
If the GDSC is enabled out of boot but doesn't have the retain ff bit set we will get confusing results where the registers that are powered by the GDSC lose their contents on the first power off of the GDSC but thereafter they retain their contents. This is because gdsc_init() fails to make sure the RETAIN_FF bit is set when it probes the GDSC the first time and thus powering off the GDSC causes the register contents to be reset. We do set the RETAIN_FF bit the next time we power on the GDSC, see gdsc_enable(), so that subsequent GDSC power off's don't lose register contents state.
Forcibly set the bit at device probe time so that the kernel's assumed view of the GDSC is consistent with the state of the hardware. This fixes a problem where the audio PLL doesn't work on sc7180 when the bootloader leaves the lpass_core_hm GDSC enabled at boot (e.g. to make a noise) but critically doesn't set the RETAIN_FF bit.
Cc: Douglas Anderson dianders@chromium.org Cc: Taniya Das tdas@codeaurora.org Cc: Rajendra Nayak rnayak@codeaurora.org Fixes: 173722995cdb ("clk: qcom: gdsc: Add support to enable retention of GSDCR") Signed-off-by: Stephen Boyd sboyd@kernel.org Link: https://lore.kernel.org/r/20201017020137.1251319-1-sboyd@kernel.org Reviewed-by: Taniya Das tdas@codeaurora.org Reviewed-by: Douglas Anderson dianders@chromium.org Tested-by: Douglas Anderson dianders@chromium.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/clk/qcom/gdsc.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c index bfc4ac02f9ea2..af26e0695b866 100644 --- a/drivers/clk/qcom/gdsc.c +++ b/drivers/clk/qcom/gdsc.c @@ -358,6 +358,14 @@ static int gdsc_init(struct gdsc *sc) if ((sc->flags & VOTABLE) && on) gdsc_enable(&sc->pd);
+ /* + * Make sure the retain bit is set if the GDSC is already on, otherwise + * we end up turning off the GDSC and destroying all the register + * contents that we thought we were saving. + */ + if ((sc->flags & RETAIN_FF_ENABLE) && on) + gdsc_retain_ff_on(sc); + /* If ALWAYS_ON GDSCs are not ON, turn them ON */ if (sc->flags & ALWAYS_ON) { if (!on)