Re: [v1 1/2] clk: qcom: gdsc: Use the default transition delay for GDSCs

Stephen Boyd
2022-02-10T07:28:46Z

Quoting Bjorn Andersson (2022-02-09 14:35:08)
> On Wed 09 Feb 11:25 CST 2022, Taniya Das wrote:
>
> > Do not update the transition delay and use the default reset values.
> >
> > Fixes: 45dd0e55317cc ("clk: qcom: Add support for GDSCs)
> > Signed-off-by: Taniya Das <tdas@codeaurora.org>
> > ---
> > drivers/clk/qcom/gdsc.c | 6 +++++-
> > drivers/clk/qcom/gdsc.h | 1 +
> > 2 files changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
> > index 7e1dd8ccfa38..e7b213450640 100644
> > --- a/drivers/clk/qcom/gdsc.c
> > +++ b/drivers/clk/qcom/gdsc.c
> > @@ -380,7 +380,11 @@ static int gdsc_init(struct gdsc *sc)
> > */
> > mask = HW_CONTROL_MASK | SW_OVERRIDE_MASK |
> > EN_REST_WAIT_MASK | EN_FEW_WAIT_MASK | CLK_DIS_WAIT_MASK;
> > - val = EN_REST_WAIT_VAL | EN_FEW_WAIT_VAL | CLK_DIS_WAIT_VAL;
> > +
> > + regmap_read(sc->regmap, sc->gdscr, &val);
> > +
> > + if (!(sc->flags & DEFAULT_TRANSITION_DELAY))
>
> I dug a little bit more into this and noticed that on various platforms
> CLK_DIS_WAIT_VAL for the GPU_CX GDSC is supposed to be 8 (whereas both
> hw default and CLK_DIS_WAIT_VAL is 2).
>
> I'm not able to find anything helpful in the git log describing what the
> value does, but it seems that a "just use hw default" flag won't cut it
> for this scenario.
>

I'd prefer we invert the logic so that we don't need to litter this flag
all over the place. I recall that the wait values were incorrect a long
time ago on early gdsc using designs but hopefully they've been fixed
now and we can simply use the default power on reset (POR) values.