linux-kernel - Re: [PATCH 2/6] clk: qcom: apss-ipq6018: fix apcs_alias0_clk

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Date:   Mon, 11 Jul 2022 17:38:13 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Robert Marko <robimarko@...il.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        krzysztof.kozlowski+dt@...aro.org, sivaprak@...eaurora.org,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-clk@...r.kernel.org,
        Devicetree List <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/6] clk: qcom: apss-ipq6018: fix apcs_alias0_clk_src

On Mon, 11 Jul 2022 at 16:23, Robert Marko <robimarko@...il.com> wrote:
>
> On Mon, 11 Jul 2022 at 14:48, Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
> >
> > On Mon, 11 Jul 2022 at 14:22, Robert Marko <robimarko@...il.com> wrote:
> > >
> > > While working on IPQ8074 APSS driver it was discovered that IPQ6018 and
> > > IPQ8074 use almost the same PLL and APSS clocks, however APSS driver is
> > > currently broken.
> > >
> > > More precisely apcs_alias0_clk_src is broken, it was added as regmap_mux
> > > clock.
> > > However after debugging why it was always stuck at 800Mhz, it was figured
> > > out that its not regmap_mux compatible at all.
> > > It is a simple mux but it uses RCG2 register layout and control bits, so
> >
> > To utilize control bits, you probably should also use
>
> Hi,
> I am not really sure what you mean here?

Ugh, excuse me. Sent the message too early.
I mean that to utilize RCG2 control bits, you probably also need to
use clk_rcg2_is_enabled, etc.

>
> >
> > > utilize the new clk_rcg2_mux_closest_ops to correctly drive it while not
> > > having to provide a dummy frequency table.
> >
> > Could you please clarify this. Your new rcg2 ops seems to be literally
> > equivalent to the clk_regmap_mux_closest_ops provided the shift and
> > width are set correctly..
>
> Well, I have tried playing with the clk_regmap_mux_closest_ops but I
> just cannot get it
> to work.
>
> The width like you pointed out should be 8, register offset is
> currently pointing at the RCG control
> register and not the CFG one, so it obviously does not work.
>
> Setting the register to 0x54 and shift to 8 will just fail silently,
> leaving the shift at 7 and correcting
> the register won't work as RCG control bits are not utilized at all
> with regmap_mux and DIRTY_CFG
> is active when I manually look at the register.

Ok, I missed the update_cfg part. So, yes, this looks correct.

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

>
> So, I am really not sure how clk_regmap_mux_closest_ops are supposed
> to work here at all.
>
> Regards,
> Robert
> >
> > > While we are here, use ARRAY_SIZE for number of parents.
> > >
> > > Tested on IPQ6018-CP01-C1 reference board and multiple IPQ8074 boards.
> > >
> > > Fixes: 5e77b4ef1b19 ("clk: qcom: Add ipq6018 apss clock controller")
> > > Signed-off-by: Robert Marko <robimarko@...il.com>
> > > ---
> > >  drivers/clk/qcom/apss-ipq6018.c | 13 ++++++-------
> > >  1 file changed, 6 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/clk/qcom/apss-ipq6018.c b/drivers/clk/qcom/apss-ipq6018.c
> > > index d78ff2f310bf..be952d417ded 100644
> > > --- a/drivers/clk/qcom/apss-ipq6018.c
> > > +++ b/drivers/clk/qcom/apss-ipq6018.c
> > > @@ -16,7 +16,7 @@
> > >  #include "clk-regmap.h"
> > >  #include "clk-branch.h"
> > >  #include "clk-alpha-pll.h"
> > > -#include "clk-regmap-mux.h"
> > > +#include "clk-rcg.h"
> > >
> > >  enum {
> > >         P_XO,
> > > @@ -33,16 +33,15 @@ static const struct parent_map parents_apcs_alias0_clk_src_map[] = {
> > >         { P_APSS_PLL_EARLY, 5 },
> > >  };
> > >
> > > -static struct clk_regmap_mux apcs_alias0_clk_src = {
> > > -       .reg = 0x0050,
> > > -       .width = 3,
> > > -       .shift = 7,
> >
> > Judging from rcg2 ops, .shift should be set to 8.
> >
> > > +static struct clk_rcg2 apcs_alias0_clk_src = {
> > > +       .cmd_rcgr = 0x0050,
> > > +       .hid_width = 5,
> > >         .parent_map = parents_apcs_alias0_clk_src_map,
> > >         .clkr.hw.init = &(struct clk_init_data){
> > >                 .name = "apcs_alias0_clk_src",
> > >                 .parent_data = parents_apcs_alias0_clk_src,
> > > -               .num_parents = 2,
> > > -               .ops = &clk_regmap_mux_closest_ops,
> > > +               .num_parents = ARRAY_SIZE(parents_apcs_alias0_clk_src),
> > > +               .ops = &clk_rcg2_mux_closest_ops,
> > >                 .flags = CLK_SET_RATE_PARENT,
> > >         },
> > >  };
> > > --
> > > 2.36.1
> > >
> >
> >
> > --
> > With best wishes
> > Dmitry



-- 
With best wishes
Dmitry