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Subject: Re: [v1 1/2] clk: qcom: gdsc: Use the default transition delay for GDSCs
From:   Stephen Boyd <sboyd@kernel.org>
Cc:     Taniya Das <tdas@codeaurora.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Rajendra Nayak <rnayak@codeaurora.org>,
        linux-arm-msm@vger.kernel.org, linux-soc@vger.kernel.org,
        linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
Date:   Thu, 17 Feb 2022 15:19:15 -0800
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Message-Id: <20220217231916.E944BC340E8@smtp.kernel.org>
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Quoting Bjorn Andersson (2022-02-10 11:32:03)
> On Thu 10 Feb 01:28 CST 2022, Stephen Boyd wrote:
>=20
> > 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.
>=20
> Are you suggesting that we make it the default to not update the values
> and then provide means to specify it where needed?

Sure!

>=20
> I like that suggestion.
>=20
> But as mentioned in my reply yesterday, GPU_CX on several platforms
> needs a different CLK_DIS_WAIT_VAL - and not the same value.
>=20
> Are these values ever 0? Or could we simply add the three numbers to
> struct gdsc and have 0 denote "use hw default"?

I don't think they're ever set to zero. That would most likely just
break things because they need a few clk cycles to wait between
transitioning states. Otherwise the GDSC gets stuck and the clks don't
work.