linux-kernel - Re: [PATCH 1/2] usb: mtu3: disable USB2 LPM

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Message-ID: <CAL411-qVjxYk7f+b74XHfj7jpxALS4LYUKe0XdSfwRZcQibNfA@mail.gmail.com>
Date:   Mon, 29 Jun 2020 15:37:54 +0800
From:   Peter Chen <hzpeterchen@...il.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        USB list <linux-usb@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        linux-mediatek@...ts.infradead.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        Markus Elfring <Markus.Elfring@....de>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/2] usb: mtu3: disable USB2 LPM

On Mon, Jun 29, 2020 at 2:04 PM Chunfeng Yun <chunfeng.yun@...iatek.com> wrote:
>
> A SuperSpeed device shall include the USB 2.0 extension descriptor
> and shall support LPM when operating in USB 2.0 HS mode(see usb3.2
> spec9.6.2.1). But we always don't support it, so disable it by
> default, otherwise device will enter LPM suspend mode when
> connected to Win10 system.

Linux also supports USB2 LPM. Besides, USB-IF CH9 test will check
LPM support if the device is USB 2.1, how could you deal with it?

Peter

>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> ---
>  drivers/usb/mtu3/mtu3_core.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/usb/mtu3/mtu3_core.c b/drivers/usb/mtu3/mtu3_core.c
> index 9dd0216..50d6a40 100644
> --- a/drivers/usb/mtu3/mtu3_core.c
> +++ b/drivers/usb/mtu3/mtu3_core.c
> @@ -604,6 +604,8 @@ static void mtu3_regs_init(struct mtu3 *mtu)
>         mtu3_clrbits(mbase, U3D_MISC_CTRL, VBUS_FRC_EN | VBUS_ON);
>         /* enable automatical HWRW from L1 */
>         mtu3_setbits(mbase, U3D_POWER_MANAGEMENT, LPM_HRWE);
> +       /* always reject LPM request */
> +       mtu3_setbits(mbase, U3D_POWER_MANAGEMENT, LPM_MODE(1));
>
>         /* use new QMU format when HW version >= 0x1003 */
>         if (mtu->gen2cp)
> --
> 1.9.1
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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