linux-kernel - Re: [RFCv1 5/5] arm64/ARM: configs: Change CONFIG_PWM

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Date:   Sun, 27 Oct 2019 00:26:03 +0530
From:   Anand Moon <linux.amoon@...il.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-amlogic@...ts.infradead.org,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RFCv1 5/5] arm64/ARM: configs: Change CONFIG_PWM_MESON from m to y

Hi Neil,

On Mon, 21 Oct 2019 at 21:11, Anand Moon <linux.amoon@...il.com> wrote:
>
> Hi Neil,
>
> On Mon, 21 Oct 2019 at 19:55, Neil Armstrong <narmstrong@...libre.com> wrote:
> >
> > Hi Anand,
> >
> > On 21/10/2019 16:11, Anand Moon wrote:
> > > Hi Martin,
> > >
> > > On Fri, 18 Oct 2019 at 23:40, Martin Blumenstingl
> > > <martin.blumenstingl@...glemail.com> wrote:
> > >>
> > >> Hi Anand,
> > >>
> > >> On Fri, Oct 18, 2019 at 4:04 PM Anand Moon <linux.amoon@...il.com> wrote:
> > >> [...]
> > >>>> Next step it to try narrow down the clock causing the issue.
> > >>>> Remove clk_ignore_unused from the command line and add CLK_INGORE_UNUSED
> > >>>> to the flag of some clocks your clock controller (g12a I think) until
> > >>>>
> > >>>> The peripheral clock gates already have this flag (something we should
> > >>>> fix someday) so don't bother looking there.
> > >>>>
> > >>>> Most likely the source of the pwm is getting disabled between the
> > >>>> late_init call and the probe of the PWM module. Since the pwm is already
> > >>>> active (w/o a driver), gating the clock source shuts dowm the power to
> > >>>> the cores.
> > >>>>
> > >>>> Looking a the possible inputs in pwm driver, I'd bet on fdiv4.
> > >>>>
> > >>>
> > >>> I had give this above steps a try but with little success.
> > >>> I am still looking into this much close.
> > >> it's not clear to me if you have only tested with the PWM and/or
> > >> FCLK_DIV4 clocks. can you please describe what you have tested so far?
> > >>
> > > Sorry for delayed response.
> > >
> > > I had just looked into clk related to SD_EMMC_A/B/C,
> > > with adding CLK_IGNORE/CRITICAL.
> > > Also looked into clk_summary for eMMC and microSD card,
> > > to identify the root cause, but I failed to move ahead.
> > >
> > >> for reference - my way of debugging this in the past was:
> > >> 1. add some printks to clk_disable_unused_subtree (right after the
> > >> clk_core_is_enabled check) to see which clocks are being disabled
> > >> 2. add CLK_IGNORE_UNUSED or CLK_IS_CRITICAL to the clocks which are
> > >> being disabled based on the information from step #1
> > >> 3. (at some point I had a working kernel with lots of clocks with
> > >> CLK_IGNORE_UNUSED/CLK_IS_CRITICAL)
> > >> 4. start dropping the CLK_IGNORE_UNUSED/CLK_IS_CRITICAL flags again
> > >> until you have traced it down to the clocks that are the actual issue
> > >> (so far I always had only one clock which caused issues, but it may be
> > >> multiple)
> > >> 5. investigate (and/or ask on the mailing list, Amlogic developers are
> > >> reading the mails here as well) for the few clocks from step #4
> > >>
> > >
> > > Thanks for you valuable suggestion. I have your patch to debug this
> > > [0]  https://patchwork.kernel.org/patch/9725921/mbox/
> > >
> > > So from the fist step I could identify that all the clk were getting closed
> > > after some core cpu clk was failing. Here is the log.
> > >
> > > step1: [1] https://pastebin.com/p13F9HGG
> > >
> > > so I marked these clk as CLK_IGNORE_UNUSED and finally
> > > I made it to boot using microSD card.
> > >
> > > After this just I converted these CLK to CLK_IS_CRITICAL
> > > as mostly these are used the CPU clk for now.
> > > Here is boot log successful for as of now.
> > >
> > > Finally: [2]  https://pastebin.com/qB6pMyGQ
> > >
> > > I know clk maintainer are against marking flags as *CLK_IS_CRITICAL*
> > > But this is just the step to move ahead.
> >
> > Thanks for the extensive debug.
> >
> > >
> > > Attach is my local clk and dts patch.Just for testing.
> > > [3] clk_critical.patch
> >
> >
> > Could you test with only the following changes:
> > diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
> > index ea4c791f106d..f49f5463363e 100644
> > --- a/drivers/clk/meson/g12a.c
> > +++ b/drivers/clk/meson/g12a.c
> > @@ -298,6 +298,7 @@ static struct clk_regmap g12a_fclk_div2 = {
> >                         &g12a_fclk_div2_div.hw
> >                 },
> >                 .num_parents = 1,
> > +               .flags = CLK_IS_CRITICAL,
> >         },
> >  };
> >
> > @@ -672,7 +673,7 @@ static struct clk_regmap g12b_cpub_clk = {
> >                         &g12a_sys_pll.hw
> >                 },
> >                 .num_parents = 2,
> > -               .flags = CLK_SET_RATE_PARENT,
> > +               .flags = CLK_SET_RATE_PARENT | CLK_IS_CRITICAL,
> >         },
> >  };
> >
>
I am blocked with my eMMC is not working with latest u-boot so that
I could not verify that nothing break with this changes.

Could you send this patch upstream with adding my.

Tested-by: Anand Moon <linux.amoon@...il.com>

Best Regards
-Anand