linux-kernel - Re: [PATCH 4.19 099/243] usb: dwc3: debugfs: Properly print/set link state for HS

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Date:   Fri, 13 Dec 2019 10:40:55 +0100
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Thinh Nguyen <thinhn@...opsys.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.19 099/243] usb: dwc3: debugfs: Properly print/set link
 state for HS

Hi!

> From: Thinh Nguyen <thinh.nguyen@...opsys.com>
> 
> [ Upstream commit 0d36dede457873404becd7c9cb9d0f2bcfd0dcd9 ]
> 
> Highspeed device and below has different state names than superspeed and
> higher. Add proper checks and printouts of link states for highspeed and
> below.

Just noticed some more oddity:
> 

> +	case DWC3_LINK_STATE_RESUME:
> +		return "Resume";
> +	default:
> +		return "UNKNOWN link state\n";
> +	}

"UNKNOWN" would be consistent with the rest of the file.

> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -433,13 +433,17 @@ static int dwc3_link_state_show(struct seq_file *s, void *unused)
>  	unsigned long		flags;
>  	enum dwc3_link_state	state;
>  	u32			reg;
> +	u8			speed;
>  
>  	spin_lock_irqsave(&dwc->lock, flags);
>  	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
>  	state = DWC3_DSTS_USBLNKST(reg);
> -	spin_unlock_irqrestore(&dwc->lock, flags);
> +	speed = reg & DWC3_DSTS_CONNECTSPD;
>  
> -	seq_printf(s, "%s\n", dwc3_gadget_link_string(state));
> +	seq_printf(s, "%s\n", (speed >= DWC3_DSTS_SUPERSPEED) ?
> +		   dwc3_gadget_link_string(state) :
> +		   dwc3_gadget_hs_link_string(state));
> +	spin_unlock_irqrestore(&dwc->lock, flags);
>  
>  	return 0;
>  }

The locking change is really wrong, right? There's no reason to do
seq_printfs under spinlock..

> @@ -477,6 +483,15 @@ static ssize_t dwc3_link_state_write(struct
file *file,
>  		return -EINVAL;
>  
>  	spin_lock_irqsave(&dwc->lock, flags);
> +	reg = dwc3_readl(dwc->regs, DWC3_DSTS);
> +	speed = reg & DWC3_DSTS_CONNECTSPD;
> +
> +	if (speed < DWC3_DSTS_SUPERSPEED &&
> +	    state != DWC3_LINK_STATE_RECOV) {
> +		spin_unlock_irqrestore(&dwc->lock, flags);
> +		return -EINVAL;
> +	}
> +
>  	dwc3_gadget_set_link_state(dwc, state);
>  	spin_unlock_irqrestore(&dwc->lock, flags);
>  

This might be ok but is not mentioned in the changelog.

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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