linux-kernel - Re: [PATCH] usb: dwc2: only prevent new request when power

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Date:   Mon, 13 Apr 2020 08:56:30 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Fabrice Gasnier <fabrice.gasnier@...com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "balbi@...com" <balbi@...com>, John Youn <John.Youn@...opsys.com>,
        "gregory.herrero@...el.com" <gregory.herrero@...el.com>,
        "Grigor.Tovmasyan@...opsys.com" <Grigor.Tovmasyan@...opsys.com>,
        "amelie.delaunay@...com" <amelie.delaunay@...com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>
Subject: Re: [PATCH] usb: dwc2: only prevent new request when power_down is
 possible

Hi,

On 4/10/2020 6:31 PM, Fabrice Gasnier wrote:
> When controller is suspended, registers mustn't be touched. This is not
> the case when 'power_down' is set to none. In this case, power saving
> routines are skipped.

If core in suspend mode even with any enabled power saving modes then 
lx_state = DWC2_L2. If power_down != DWC2_POWER_DOWN_PARAM_NONE it 
doesn't mean that core in suspend state (DWC2_L2) and declining request 
is wrong. So, additional checking of params.power_dowm here is not correct.

> 
> This fixes a case where gadget driver (f_acm) gets opened (cat /dev/ttyGS0)
> but the bus has been suspended by the host:
> - configfs-gadget gadget: acm ttyGS0 can't notify serial state, -11
> 
> Fixes: 7ababa926c66 ("usb: dwc2: gadget: prevent new request submission during suspend")
> Fixes: 88b02f2cb1e1 ("usb: dwc2: Add core state checking")
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
> ---
>   drivers/usb/dwc2/gadget.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
> index 92ed32e..45a8782 100644
> --- a/drivers/usb/dwc2/gadget.c
> +++ b/drivers/usb/dwc2/gadget.c
> @@ -1375,7 +1375,8 @@ static int dwc2_hsotg_ep_queue(struct usb_ep *ep, struct usb_request *req,
>   		req->zero, req->short_not_ok);
>   
>   	/* Prevent new request submission when controller is suspended */
> -	if (hs->lx_state != DWC2_L0) {
> +	if (hs->params.power_down != DWC2_POWER_DOWN_PARAM_NONE &&
> +	    hs->lx_state != DWC2_L0) {
>   		dev_dbg(hs->dev, "%s: submit request only in active state\n",
>   			__func__);
>   		return -EAGAIN;
>