linux-kernel - Re: [PATCH v2 4/4] clk: qcom: lpass: Add support for LPASS clock controller for SC7180

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Message-ID: <159183760269.242598.3005455698894049563@swboyd.mtv.corp.google.com>
Date:   Wed, 10 Jun 2020 18:06:42 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Michael Turquette <mturquette@...libre.com>,
        Taniya Das <tdas@...eaurora.org>
Cc:     David Brown <david.brown@...aro.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andy Gross <agross@...nel.org>, devicetree@...r.kernel.org,
        robh@...nel.org, robh+dt@...nel.org
Subject: Re: [PATCH v2 4/4] clk: qcom: lpass: Add support for LPASS clock controller for SC7180

Quoting Taniya Das (2020-06-10 10:11:49)
> On 5/27/2020 8:40 AM, Stephen Boyd wrote:
> > Quoting Taniya Das (2020-05-17 02:22:24)
> >> +       if (ret)
> >> +               return ret;
> >> +
> >> +       lpass_core_cc_sc7180_regmap_config.name = "lpass_core_cc";
> >> +       regmap = qcom_cc_map(pdev, &lpass_core_cc_sc7180_desc);
> >> +       if (IS_ERR(regmap))
> >> +               return PTR_ERR(regmap);
> >> +
> >> +       /*
> >> +        * Keep the CLK always-ON
> > 
> > Why? Presumably to make sure we can access the lpass sysnoc path all the
> > time?
> > 
> 
> This is an always ON clock from HW, just making sure to keep it enabled.

I'm not following. Hardware says it must always be enabled? If it isn't
enabled is it even possible to write this register?

> 
> >> +        * LPASS_AUDIO_CORE_SYSNOC_SWAY_CORE_CLK
> >> +        */
> >> +       regmap_update_bits(regmap, 0x24000, BIT(0), BIT(0));
> >> +