Re: mceusb xhci issue?

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I never received any replies to this message.  Should the patch I 
suggested be merged?

Alan Stern


On Tue, 12 Jul 2016, Alan Stern wrote:

> On Sat, 9 Jul 2016, Mauro Carvalho Chehab wrote:
> 
> > C/C linux-usb Mailing list:
> > 
> > 
> > Em Wed, 18 May 2016 08:52:28 -0600
> > Wade Berrier <wberrier@xxxxxxxxx> escreveu:
> 
> ...
> 
> > > > That message above links to some other threads describing the issue.
> > > > Here's a post with a patch that supposedly works:
> > > > 
> > > > http://www.gossamer-threads.com/lists/mythtv/users/587930
> > > > 
> > > > No idea if that's the "correct" way to fix this.
> > > > 
> > > > I'll be trying that out and then report back...  
> > > 
> > > Indeed, this patch does fix the issue:
> > > 
> > > ----------------------
> > > 
> > > diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> > > index 31ccdcc..03321d4 100644
> > > --- a/drivers/usb/core/config.c
> > > +++ b/drivers/usb/core/config.c
> > > @@ -247,7 +247,7 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
> > >  			/* For low-speed, 10 ms is the official minimum.
> > >  			 * But some "overclocked" devices might want faster
> > >  			 * polling so we'll allow it. */
> > > -			n = 32;
> > > +			n = 10;
> > >  			break;
> > >  		}
> > >  	} else if (usb_endpoint_xfer_isoc(d)) {
> > > 
> > > 
> > > ----------------------
> > > 
> > > Is this change appropriate to be pushed upstream?  Where to go from
> > > here?
> > 
> > This issue is at the USB core. So, it should be reported to the
> > linux-usb mailing list. 
> > 
> > The people there should help about how to proceed to get this
> > fixed upstream.
> 
> Here's a proper version of that patch.  If this is okay, it can be 
> merged.
> 
> Alan Stern
> 
> 
> 
> Index: usb-4.x/drivers/usb/core/config.c
> ===================================================================
> --- usb-4.x.orig/drivers/usb/core/config.c
> +++ usb-4.x/drivers/usb/core/config.c
> @@ -213,8 +213,10 @@ static int usb_parse_endpoint(struct dev
>  	memcpy(&endpoint->desc, d, n);
>  	INIT_LIST_HEAD(&endpoint->urb_list);
>  
> -	/* Fix up bInterval values outside the legal range. Use 32 ms if no
> -	 * proper value can be guessed. */
> +	/*
> +	 * Fix up bInterval values outside the legal range.
> +	 * Use 10 or 8 ms if no proper value can be guessed.
> +	 */
>  	i = 0;		/* i = min, j = max, n = default */
>  	j = 255;
>  	if (usb_endpoint_xfer_int(d)) {
> @@ -223,13 +225,15 @@ static int usb_parse_endpoint(struct dev
>  		case USB_SPEED_SUPER_PLUS:
>  		case USB_SPEED_SUPER:
>  		case USB_SPEED_HIGH:
> -			/* Many device manufacturers are using full-speed
> +			/*
> +			 * Many device manufacturers are using full-speed
>  			 * bInterval values in high-speed interrupt endpoint
>  			 * descriptors. Try to fix those and fall back to a
> -			 * 32 ms default value otherwise. */
> +			 * 8 ms default value otherwise.
> +			 */
>  			n = fls(d->bInterval*8);
>  			if (n == 0)
> -				n = 9;	/* 32 ms = 2^(9-1) uframes */
> +				n = 7;	/* 8 ms = 2^(7-1) uframes */
>  			j = 16;
>  
>  			/*
> @@ -247,7 +251,7 @@ static int usb_parse_endpoint(struct dev
>  			/* For low-speed, 10 ms is the official minimum.
>  			 * But some "overclocked" devices might want faster
>  			 * polling so we'll allow it. */
> -			n = 32;
> +			n = 10;
>  			break;
>  		}
>  	} else if (usb_endpoint_xfer_isoc(d)) {
> @@ -255,10 +259,10 @@ static int usb_parse_endpoint(struct dev
>  		j = 16;
>  		switch (to_usb_device(ddev)->speed) {
>  		case USB_SPEED_HIGH:
> -			n = 9;		/* 32 ms = 2^(9-1) uframes */
> +			n = 7;		/* 8 ms = 2^(7-1) uframes */
>  			break;
>  		default:		/* USB_SPEED_FULL */
> -			n = 6;		/* 32 ms = 2^(6-1) frames */
> +			n = 4;		/* 8 ms = 2^(4-1) frames */
>  			break;
>  		}
>  	}


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