linux-kernel - Re: [PATCH 1/6] arm64: dts: rockchip: Fix rk3399-roc-pc pwm2 pin

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Message-ID: <CAMty3ZDKaywoPxCSD-5N2pLjtGmZ-dZ7ZgUOJqiB1V_9rfR26A@mail.gmail.com>
Date:   Tue, 1 Oct 2019 15:56:14 +0530
From:   Jagan Teki <jagan@...rulasolutions.com>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Levin Du <djw@...hip.com.cn>, Akash Gajjar <akash@...nedev.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Da Xue <da@...sconfused.com>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-amarula <linux-amarula@...rulasolutions.com>
Subject: Re: [PATCH 1/6] arm64: dts: rockchip: Fix rk3399-roc-pc pwm2 pin

Hi Heiko,

On Mon, Sep 30, 2019 at 2:51 AM Heiko Stuebner <heiko@...ech.de> wrote:
>
> Hi Jagan,
>
> Am Donnerstag, 19. September 2019, 07:28:17 CEST schrieb Jagan Teki:
> > ROC-PC is not able to boot linux console if PWM2_d is
> > unattached to any pinctrl logic.
> >
> > To be precise the linux boot hang with last logs as,
> > ...
> > .....
> > [    0.003367] Console: colour dummy device 80x25
> > [    0.003788] printk: console [tty0] enabled
> > [    0.004178] printk: bootconsole [uart8250] disabled
> >
> > In ROC-PC the PWM2_d pin is connected to LOG_DVS_PWM of
> > VDD_LOG. So, for normal working operations this needs to
> > active and pull-down.
> >
> > This patch fix, by attaching pinctrl active and pull-down
> > the pwm2.
>
> This looks highly dubious on first glance. The pwm subsystem nor
> the Rockchip pwm driver do not do any pinctrl handling.
>
> So I don't really see where that "active" pinctrl state is supposed
> to come from.
>
> Comparing with the pwm driver in the vendor tree I see that there
> is such a state defined there. But that code there also looks strange
> as that driver never again leaves this active state after entering it.
>
> Also for example all the Gru devices run with quite a number of pwm-
> regulators without needing additional fiddling with the pwm itself, so
> I don't really see why that should be different here.

I deed, I was supposed to think the same. but the vendor kernel dts
from firefly do follow the pwm2 pinctrl [1]. I wouldn't find any
information other than this vensor information, ie one of the reason I
have marked "Levin Du" who initially supported this board.

One, think I have seen was this pinctrl active fixed the boot hang.
any inputs from would be very helpful.

Levin Du, any inputs?

[1] https://github.com/FireflyTeam/kernel/blob/stable-4.4-rk3399-linux/arch/arm64/boot/dts/rockchip/rk3399-roc-pc.dtsi#L1184