linux-kernel - Re: [PATCH v2 3/3] clk: qcom: clk-krait: add apq/ipq8064 errata workaround

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Date:   Sat, 30 Apr 2022 16:25:17 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] clk: qcom: clk-krait: add apq/ipq8064 errata workaround

On Sat, 30 Apr 2022 at 15:53, Ansuel Smith <ansuelsmth@...il.com> wrote:
>
> Add apq/ipq8064 errata workaround where the sec_src clock gating needs to
> be disabled during switching. krait-cc compatible is not enough to
> handle this and limit this workaround to apq/ipq8064. We check machine
> compatible to handle this.
>
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

> ---
>  drivers/clk/qcom/clk-krait.c | 16 ++++++++++++++++
>  drivers/clk/qcom/clk-krait.h |  1 +
>  drivers/clk/qcom/krait-cc.c  |  8 ++++++++
>  3 files changed, 25 insertions(+)
>
> diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> index 90046428693c..45da736bd5f4 100644
> --- a/drivers/clk/qcom/clk-krait.c
> +++ b/drivers/clk/qcom/clk-krait.c
> @@ -18,13 +18,23 @@
>  static DEFINE_SPINLOCK(krait_clock_reg_lock);
>
>  #define LPL_SHIFT      8
> +#define SECCLKAGD      BIT(4)
> +
>  static void __krait_mux_set_sel(struct krait_mux_clk *mux, int sel)
>  {
>         unsigned long flags;
>         u32 regval;
>
>         spin_lock_irqsave(&krait_clock_reg_lock, flags);
> +
>         regval = krait_get_l2_indirect_reg(mux->offset);
> +
> +       /* apq/ipq8064 Errata: disable sec_src clock gating during switch. */
> +       if (mux->disable_sec_src_gating) {
> +               regval |= SECCLKAGD;
> +               krait_set_l2_indirect_reg(mux->offset, regval);
> +       }
> +
>         regval &= ~(mux->mask << mux->shift);
>         regval |= (sel & mux->mask) << mux->shift;
>         if (mux->lpl) {
> @@ -33,6 +43,12 @@ static void __krait_mux_set_sel(struct krait_mux_clk *mux, int sel)
>         }
>         krait_set_l2_indirect_reg(mux->offset, regval);
>
> +       /* apq/ipq8064 Errata: re-enabled sec_src clock gating. */
> +       if (mux->disable_sec_src_gating) {
> +               regval &= ~SECCLKAGD;
> +               krait_set_l2_indirect_reg(mux->offset, regval);
> +       }
> +
>         /* Wait for switch to complete. */
>         mb();
>         udelay(1);
> diff --git a/drivers/clk/qcom/clk-krait.h b/drivers/clk/qcom/clk-krait.h
> index 9120bd2f5297..f930538c539e 100644
> --- a/drivers/clk/qcom/clk-krait.h
> +++ b/drivers/clk/qcom/clk-krait.h
> @@ -15,6 +15,7 @@ struct krait_mux_clk {
>         u8              safe_sel;
>         u8              old_index;
>         bool            reparent;
> +       bool            disable_sec_src_gating;
>
>         struct clk_hw   hw;
>         struct notifier_block   clk_nb;
> diff --git a/drivers/clk/qcom/krait-cc.c b/drivers/clk/qcom/krait-cc.c
> index 4d4b657d33c3..cfd961d5cc45 100644
> --- a/drivers/clk/qcom/krait-cc.c
> +++ b/drivers/clk/qcom/krait-cc.c
> @@ -139,6 +139,14 @@ krait_add_sec_mux(struct device *dev, int id, const char *s,
>         mux->hw.init = &init;
>         mux->safe_sel = 0;
>
> +       /* Checking for qcom,krait-cc-v1 or qcom,krait-cc-v2 is not
> +        * enough to limit this to apq/ipq8064. Directly check machine
> +        * compatible to correctly handle this errata.
> +        */
> +       if (of_machine_is_compatible("qcom,ipq8064") ||
> +           of_machine_is_compatible("qcom,apq8064"))
> +               mux->disable_sec_src_gating = true;
> +
>         init.name = kasprintf(GFP_KERNEL, "krait%s_sec_mux", s);
>         if (!init.name)
>                 return -ENOMEM;
> --
> 2.34.1
>


-- 
With best wishes
Dmitry