linux-kernel - Re: [PATCH] clk: at91: sama5d2: Mark device OF

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Message-ID: <161285731192.418021.10555916396092570051@swboyd.mtv.corp.google.com>
Date:   Mon, 08 Feb 2021 23:55:11 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Saravana Kannan <saravanak@...gle.com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>
Cc:     Michael Turquette <mturquette@...libre.com>,
        nicolas.ferre@...rochip.com, alexandre.belloni@...tlin.com,
        ludovic.desroches@...rochip.com, claudiu.beznea@...rochip.com,
        mirq-linux@...e.qmqm.pl,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-clk@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: at91: sama5d2: Mark device OF_POPULATED after setup

Quoting Saravana Kannan (2021-01-28 09:01:41)
> On Thu, Jan 28, 2021 at 2:45 AM Tudor Ambarus
> <tudor.ambarus@...rochip.com> wrote:
> >
> > The sama5d2 requires the clock provider initialized before timers.
> > We can't use a platform driver for the sama5d2-pmc driver, as the
> > platform_bus_init() is called later on, after time_init().
> >
> > As fw_devlink considers only devices, it does not know that the
> > pmc is ready. Hence probing of devices that depend on it fail:
> > probe deferral - supplier f0014000.pmc not ready
> >
> > Fix this by setting the OF_POPULATED flag for the sama5d2_pmc
> > device node after successful setup. This will make
> > of_link_to_phandle() ignore the sama5d2_pmc device node as a
> > dependency, and consumer devices will be probed again.
> >
> > Fixes: e590474768f1cc04 ("driver core: Set fw_devlink=on by default")
> > Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> > ---
> > I'll be out of office, will check the rest of the at91 SoCs
> > at the begining of next week.
> >
> >  drivers/clk/at91/sama5d2.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/clk/at91/sama5d2.c b/drivers/clk/at91/sama5d2.c
> > index 9a5cbc7cd55a..5eea2b4a63dd 100644
> > --- a/drivers/clk/at91/sama5d2.c
> > +++ b/drivers/clk/at91/sama5d2.c
> > @@ -367,6 +367,8 @@ static void __init sama5d2_pmc_setup(struct device_node *np)
> >
> >         of_clk_add_hw_provider(np, of_clk_hw_pmc_get, sama5d2_pmc);
> >
> > +       of_node_set_flag(np, OF_POPULATED);
> > +
> >         return;
> 
> Hi Tudor,
> 
> Thanks for looking into this.
> 
> I already accounted for early clocks like this when I designed
> fw_devlink. Each driver shouldn't need to set OF_POPULATED.
> drivers/clk/clk.c already does this for you.
> 
> I think the problem is that your driver is using
> CLK_OF_DECLARE_DRIVER() instead of CLK_OF_DECLARE(). The comments for
> CLK_OF_DECLARE_DRIVER() says:
> /*
>  * Use this macro when you have a driver that requires two initialization
>  * routines, one at of_clk_init(), and one at platform device probe
>  */
> 
> In your case, you are explicitly NOT having a driver bind to this
> clock later. So you shouldn't be using CLK_OF_DECLARE() instead.
> 

I see 

drivers/power/reset/at91-sama5d2_shdwc.c:       { .compatible = "atmel,sama5d2-pmc" },

so isn't that the driver that wants to bind to the same device node
again? First at of_clk_init() time here and then second for the reset
driver?