linux-kernel - Re: [PATCH 12/16] clk: qcom: clk-krait: add 8064 errata workaround

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Date:   Mon, 14 Mar 2022 13:43:20 +0100
From:   Ansuel Smith <ansuelsmth@...il.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: Re: [PATCH 12/16] clk: qcom: clk-krait: add 8064 errata workaround

On Mon, Mar 14, 2022 at 11:20:21AM +0300, Dmitry Baryshkov wrote:
> On 13/03/2022 22:04, Ansuel Smith wrote:
> > Add 8064 errata workaround where the sec_src clock gating needs to be
> 
> Could you please be more specific whether the errata applies only to the
> ipq8064 or to the apq8064 too? 8064 is not specific enough.
>

That's a good question... Problem is that we really don't know the
answer. This errata comes from qsdk on an old sourcecode. I assume this
is specific to ipq8064 and apq8064 have different mux configuration.

> > disabled during switching. To enable this set disable_sec_src_gating in
> > the mux struct.
> > 
> > Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> > ---
> >   drivers/clk/qcom/clk-krait.c | 16 ++++++++++++++++
> >   drivers/clk/qcom/clk-krait.h |  1 +
> >   drivers/clk/qcom/krait-cc.c  |  1 +
> >   3 files changed, 18 insertions(+)
> > 
> > diff --git a/drivers/clk/qcom/clk-krait.c b/drivers/clk/qcom/clk-krait.c
> > index d8af281eba0e..82fe7031e1f4 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);
> > +
> > +	/* 8064 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);
> > +	/* 8064 Errata: re-enabled sec_src clock gating. */
> 
> And here too
> 
> > +	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 1bdc89c097e6..533a770332be 100644
> > --- a/drivers/clk/qcom/krait-cc.c
> > +++ b/drivers/clk/qcom/krait-cc.c
> > @@ -154,6 +154,7 @@ krait_add_sec_mux(struct device *dev, struct clk *qsb, int id,
> >   	mux->shift = 2;
> >   	mux->parent_map = sec_mux_map;
> >   	mux->hw.init = &init;
> > +	mux->disable_sec_src_gating = true;
> >   	init.name = kasprintf(GFP_KERNEL, "krait%s_sec_mux", s);
> >   	if (!init.name)
> 
> 
> -- 
> With best wishes
> Dmitry

-- 
	Ansuel