Quoting Bjorn Andersson (2021-07-21 15:40:56)
> As GDSCs are registered and found to be already enabled gdsc_init()
> ensures that 1) the kernel state matches the hardware state, and 2)
> votable GDSCs are properly enabled from this master as well.
>
> But as the (optional) supply regulator is enabled deep into
> gdsc_toggle_logic(), which is only executed for votable GDSCs the
> kernel's state of the regulator might not match the hardware. The
> regulator might be automatically turned off if no other users are
> present or the next call to gdsc_disable() would cause an unbalanced
> regulator_disable().
>
> But as the votable case deals with an already enabled GDSC, most of
> gdsc_enable() and gdsc_toggle_logic() can be skipped. Reducing it to
> just clearing the SW_COLLAPSE_MASK and enabling hardware control allow
> us to simply call regulator_enable() in both cases.
>
> The enablement of hardware control seems to be an independent property
> from the GDSC being enabled, so this is moved outside that conditional
> segment.
>
> Lastly, as the propagation of ALWAY_ON to GENPD_FLAG_ALWAYS_ON needs to
> happen regardless of the initial state this is grouped together with the
> other sc->pd updates at the end of the function.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 37416e554961 ("clk: qcom: gdsc: Handle GDSC regulator supplies")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> ---
I was hoping someone from qcom would review it. I'll take a look in the
next couple of days and probably throw it on clk-fixes for the next rc.
-Stephen
>
> Changes since v1:
> - Refactored into if (on) else if (ALWAYS_ON) style
> - Extracted relevant parts of gdsc_enable() to call under VOTABLE
> - Turn on hwctrl if requested for non-votable gdscs
>
> drivers/clk/qcom/gdsc.c | 54 +++++++++++++++++++++++++++--------------
> 1 file changed, 36 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> index 51ed640e527b..4ece326ea233 100644
> --- a/drivers/clk/qcom/gdsc.c
> +++ b/drivers/clk/qcom/gdsc.c
> @@ -357,27 +357,43 @@ static int gdsc_init(struct gdsc *sc)
> if (on < 0)
> return on;
>
> - /*
> - * Votable GDSCs can be ON due to Vote from other masters.
> - * If a Votable GDSC is ON, make sure we have a Vote.
> - */
> - if ((sc->flags & VOTABLE) && on)
> - gdsc_enable(&sc->pd);
> + if (on) {
> + /* The regulator must be on, sync the kernel state */
> + if (sc->rsupply) {
> + ret = regulator_enable(sc->rsupply);
> + if (ret < 0)
> + return ret;
> + }
>
> - /*
> - * 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);
> + /*
> + * Votable GDSCs can be ON due to Vote from other masters.
> + * If a Votable GDSC is ON, make sure we have a Vote.
> + */
> + if (sc->flags & VOTABLE) {
> + ret = regmap_update_bits(sc->regmap, sc->gdscr,
> + SW_COLLAPSE_MASK, val);
> + if (ret)
> + return ret;
> + }
> +
> + /* Turn on HW trigger mode if supported */
> + if (sc->flags & HW_CTRL) {
> + ret = gdsc_hwctrl(sc, true);
> + if (ret < 0)
> + return ret;
> + }
>
> - /* If ALWAYS_ON GDSCs are not ON, turn them ON */
> - if (sc->flags & ALWAYS_ON) {
> - if (!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)
> + gdsc_retain_ff_on(sc);
> + } else if (sc->flags & ALWAYS_ON) {
> + /* If ALWAYS_ON GDSCs are not ON, turn them ON */
> + gdsc_enable(&sc->pd);
> on = true;
> - sc->pd.flags |= GENPD_FLAG_ALWAYS_ON;
> }
>
> if (on || (sc->pwrsts & PWRSTS_RET))
> @@ -385,6 +401,8 @@ static int gdsc_init(struct gdsc *sc)
> else
> gdsc_clear_mem_on(sc);
>
> + if (sc->flags & ALWAYS_ON)
> + sc->pd.flags |= GENPD_FLAG_ALWAYS_ON;
> if (!sc->pd.power_off)
> sc->pd.power_off = gdsc_disable;
> if (!sc->pd.power_on)
> --
> 2.29.2
>
