linux-kernel - Re: [PATCH 2/4] usb: host: ehci-platform: Call reset assert/deassert on suspend/resume

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMuHMdWDGpqdhCsA0MJqoL1JAiyVR-TA2YqDe+-S9Xf6c5O-gA@mail.gmail.com>
Date: Thu, 6 Nov 2025 15:52:47 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Claudiu <claudiu.beznea@...on.dev>
Cc: stern@...land.harvard.edu, gregkh@...uxfoundation.org, 
	p.zabel@...gutronix.de, yoshihiro.shimoda.uh@...esas.com, 
	prabhakar.mahadev-lad.rj@...renesas.com, kuninori.morimoto.gx@...esas.com, 
	geert+renesas@...der.be, linux-usb@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH 2/4] usb: host: ehci-platform: Call reset assert/deassert
 on suspend/resume

Hi Claudiu,

On Thu, 6 Nov 2025 at 15:36, Claudiu <claudiu.beznea@...on.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
>
> The Renesas RZ/G3S SoC supports a power-saving mode in which power to most
> of the SoC components is turned off, including the USB blocks. On the
> resume path, the reset signal must be de-asserted before applying any
> settings to the USB registers. To handle this properly, call
> reset_control_assert() and reset_control_deassert() during suspend and
> resume, respectively.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

Thanks for your patch!

> --- a/drivers/usb/host/ehci-platform.c
> +++ b/drivers/usb/host/ehci-platform.c
> @@ -454,6 +454,17 @@ static int __maybe_unused ehci_platform_suspend(struct device *dev)
>         if (pdata->power_suspend)
>                 pdata->power_suspend(pdev);
>
> +       ret = reset_control_assert(priv->rsts);
> +       if (ret) {
> +               if (pdata->power_on)
> +                       pdata->power_on(pdev);
> +
> +               ehci_resume(hcd, false);
> +
> +               if (priv->quirk_poll)
> +                       quirk_poll_init(priv);

I have my doubts about the effectiveness of this "reverse error
handling".  If the reset_control_assert() failed, what are the chances
that the device will actually work after trying to bring it up again?

Same comment for next patch.

> +       }
> +
>         return ret;
>  }
>

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