linux-kernel - Re: [PATCH 3/7] soc: renesas: r9a06g032-sysctrl: Handle h2mode device-tree property

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Message-ID: <20221107173614.474707d7@bootlin.com>
Date:   Mon, 7 Nov 2022 17:36:14 +0100
From:   Herve Codina <herve.codina@...tlin.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Magnus Damm <magnus.damm@...il.com>,
        Gareth Williams <gareth.williams.jx@...esas.com>,
        linux-renesas-soc@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH 3/7] soc: renesas: r9a06g032-sysctrl: Handle h2mode
 device-tree property

Hi Geert,

On Mon, 7 Nov 2022 16:18:06 +0100
Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

> Hi Hervé,
> 
> On Mon, Nov 7, 2022 at 2:59 PM Herve Codina <herve.codina@...tlin.com> wrote:
> > Handle the h2mode property and forces the CFG_USB[H2MODE] bit
> > accordingly.
> >
> > Signed-off-by: Herve Codina <herve.codina@...tlin.com>  
> 
> Thanks for your patch!
> 
> > --- a/drivers/clk/renesas/r9a06g032-clocks.c
> > +++ b/drivers/clk/renesas/r9a06g032-clocks.c
> > @@ -946,6 +946,7 @@ static int __init r9a06g032_clocks_probe(struct platform_device *pdev)
> >         struct clk *mclk;
> >         unsigned int i;
> >         u16 uart_group_sel[2];
> > +       u32 usb, h2mode;
> >         int error;
> >
> >         clocks = devm_kzalloc(dev, sizeof(*clocks), GFP_KERNEL);
> > @@ -966,6 +967,26 @@ static int __init r9a06g032_clocks_probe(struct platform_device *pdev)
> >         clocks->reg = of_iomap(np, 0);
> >         if (WARN_ON(!clocks->reg))
> >                 return -ENOMEM;
> > +
> > +       error = of_property_read_u32(np, "renesas,h2mode", &h2mode);
> > +       if (!error) {
> > +               usb = readl(clocks->reg + R9A06G032_SYSCTRL_USB);
> > +               switch (h2mode) {
> > +               case 0:
> > +                       /* 1 host, 1 device */
> > +                       usb &= ~R9A06G032_SYSCTRL_USB_H2MODE;
> > +                       break;
> > +               case 1:
> > +                       /* 2 hosts */
> > +                       usb |= R9A06G032_SYSCTRL_USB_H2MODE;
> > +                       break;
> > +               default:
> > +                       dev_err(dev, "invalid h2mode %d\n", h2mode);
> > +                       return -EINVAL;
> > +               }
> > +               writel(usb, clocks->reg + R9A06G032_SYSCTRL_USB);  
> 
> Reading the big fat warnings in the documentation about changing
> this at runtime (disconnect nodes, reset clocks, ...), I'm wondering if
> the above is sufficient?

Well, indeed we should "disconnect all module operated by USBPLL clock 
from the NoC interconnect".

I am a bit lost in the sysctrl driver and the clock/reset stuffs.
In fact, I don't really know how to do that.

I thought that setting the H2MODE value at the clock probe function would
be sufficient, expecting that the connections would not be already done
and I didn't see any issues on my system.

Maybe I missed the bootloader that could have already done some connections.

Can someone help ?

> 
> > +       }
> > +
> >         for (i = 0; i < ARRAY_SIZE(r9a06g032_clocks); ++i) {
> >                 const struct r9a06g032_clkdesc *d = &r9a06g032_clocks[i];
> >                 const char *parent_name = d->source ?  
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

Thanks,
Hervé

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com