[PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[Rainer Weikusat]

At least the Keyspan USA-19HS USB-to-serial converter supports
two different configurations, one where the input endpoints
have interrupt transfer type and one where they are bulk endpoints.
The default UHCI configuration uses the interrupt input endpoints.
The keyspan driver, OTOH, assumes that the device has only bulk
endpoints (all URBs are initialized by calling usb_fill_bulk_urb
in keyspan.c/ keyspan_setup_urb). This causes the interval field
of the input URBs to have a value of zero instead of one, which
'accidentally' worked with Linux at least up to 2.6.17.11 but
stopped to with 2.6.18, which changed the UHCI support code handling
URBs for interrupt endpoints. The patch below modifies to driver to
initialize its input URBs either as interrupt or as bulk URBs,
depending on the transfertype contained in the associated endpoint
descriptor (only tested with the default configuration) enabling
the driver to again receive data from the serial converter.

Signed-off-by: Rainer Weikusat <rweikusat@sncag.com>
---
diff -pNur linux-2.6.20-rc3/drivers/usb/serial/keyspan.c linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c
--- linux-2.6.20-rc3/drivers/usb/serial/keyspan.c	2007-01-02 11:10:22.000000000 +0100
+++ linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c	2007-01-02 18:54:16.000000000 +0100
@@ -95,6 +95,7 @@
 */
 
 
+#include <linux/compiler.h>
 #include <linux/kernel.h>
 #include <linux/jiffies.h>
 #include <linux/errno.h>
@@ -1275,11 +1276,29 @@ static int keyspan_fake_startup (struct 
 }
 
 /* Helper functions used by keyspan_setup_urbs */
+static struct usb_endpoint_descriptor const *
+find_ep_desc_for(struct usb_serial const *serial, int endpoint)
+{
+	struct usb_host_endpoint const *p, *e;
+
+	p = serial->interface->cur_altsetting->endpoint;
+	e = p + serial->interface->cur_altsetting->desc.bNumEndpoints;
+	while (p < e && p->desc.bEndpointAddress != endpoint) ++p;
+	
+	if (unlikely(p == e)) panic("found no endpoint descriptor for "
+				    "endpoint %d\n", endpoint);
+
+	return &p->desc;
+}
+
 static struct urb *keyspan_setup_urb (struct usb_serial *serial, int endpoint,
 				      int dir, void *ctx, char *buf, int len,
 				      void (*callback)(struct urb *))
 {
 	struct urb *urb;
+	struct usb_endpoint_descriptor const *ep_desc;
+	char const *ep_type_name;
+	unsigned ep_type;
 
 	if (endpoint == -1)
 		return NULL;		/* endpoint not needed */
@@ -1290,12 +1309,31 @@ static struct urb *keyspan_setup_urb (st
 		dbg ("%s - alloc for endpoint %d failed.", __FUNCTION__, endpoint);
 		return NULL;
 	}
+	
+	ep_desc = find_ep_desc_for(serial, endpoint);
+	ep_type = ep_desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
+	switch (ep_type) {
+	case USB_ENDPOINT_XFER_INT:
+		ep_type_name = "INT";
+		usb_fill_int_urb(urb, serial->dev,
+				 usb_sndintpipe(serial->dev, endpoint) | dir,
+				 buf, len, callback, ctx,
+				 ep_desc->bInterval);
+		break;
+
+	case USB_ENDPOINT_XFER_BULK:
+		ep_type_name = "BULK";
+		usb_fill_bulk_urb(urb, serial->dev,
+				  usb_sndbulkpipe(serial->dev, endpoint) | dir,
+				  buf, len, callback, ctx);
+		break;
 
-		/* Fill URB using supplied data. */
-	usb_fill_bulk_urb(urb, serial->dev,
-		      usb_sndbulkpipe(serial->dev, endpoint) | dir,
-		      buf, len, callback, ctx);
+	default:
+		panic("unsupported endpoint type %d", ep_type);
+	}
 
+	dbg("%s - using urb %p for %s endpoint %d",
+	    __func__, urb, ep_type_name, endpoint);
 	return urb;
 }
 

Re: [PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[Greg KH]

On Tue, Jan 02, 2007 at 07:16:54PM +0100, Rainer Weikusat wrote:
> At least the Keyspan USA-19HS USB-to-serial converter supports
> two different configurations, one where the input endpoints
> have interrupt transfer type and one where they are bulk endpoints.
> The default UHCI configuration uses the interrupt input endpoints.
> The keyspan driver, OTOH, assumes that the device has only bulk
> endpoints (all URBs are initialized by calling usb_fill_bulk_urb
> in keyspan.c/ keyspan_setup_urb).

So, this means that Keyspan changed the USB configuration of this
device?

Can you send me the output of 'cat /proc/bus/usb/devices' with this
keyspan device plugged in?  I'll compare it with the devices I have
here.

> This causes the interval field
> of the input URBs to have a value of zero instead of one, which
> 'accidentally' worked with Linux at least up to 2.6.17.11 but
> stopped to with 2.6.18, which changed the UHCI support code handling
> URBs for interrupt endpoints. The patch below modifies to driver to
> initialize its input URBs either as interrupt or as bulk URBs,
> depending on the transfertype contained in the associated endpoint
> descriptor (only tested with the default configuration) enabling
> the driver to again receive data from the serial converter.
> 
> Signed-off-by: Rainer Weikusat <rweikusat@sncag.com>
> ---
> diff -pNur linux-2.6.20-rc3/drivers/usb/serial/keyspan.c linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c
> --- linux-2.6.20-rc3/drivers/usb/serial/keyspan.c	2007-01-02 11:10:22.000000000 +0100
> +++ linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c	2007-01-02 18:54:16.000000000 +0100
> @@ -95,6 +95,7 @@
>  */
>  
>  
> +#include <linux/compiler.h>
>  #include <linux/kernel.h>
>  #include <linux/jiffies.h>
>  #include <linux/errno.h>
> @@ -1275,11 +1276,29 @@ static int keyspan_fake_startup (struct 
>  }
>  
>  /* Helper functions used by keyspan_setup_urbs */
> +static struct usb_endpoint_descriptor const *
> +find_ep_desc_for(struct usb_serial const *serial, int endpoint)
> +{
> +	struct usb_host_endpoint const *p, *e;
> +
> +	p = serial->interface->cur_altsetting->endpoint;
> +	e = p + serial->interface->cur_altsetting->desc.bNumEndpoints;
> +	while (p < e && p->desc.bEndpointAddress != endpoint) ++p;
> +	
> +	if (unlikely(p == e)) panic("found no endpoint descriptor for "
> +				    "endpoint %d\n", endpoint);

No need for "unlikely" on such a slow path.

Also, panic() should be on the next line for the proper coding style.

And, we don't want to panic() for such a trivial thing.  Just abort the
probe sequence at most, but never shut down the machine for an odd
device that we find.

> +
> +	return &p->desc;
> +}
> +
>  static struct urb *keyspan_setup_urb (struct usb_serial *serial, int endpoint,
>  				      int dir, void *ctx, char *buf, int len,
>  				      void (*callback)(struct urb *))
>  {
>  	struct urb *urb;
> +	struct usb_endpoint_descriptor const *ep_desc;
> +	char const *ep_type_name;
> +	unsigned ep_type;
>  
>  	if (endpoint == -1)
>  		return NULL;		/* endpoint not needed */
> @@ -1290,12 +1309,31 @@ static struct urb *keyspan_setup_urb (st
>  		dbg ("%s - alloc for endpoint %d failed.", __FUNCTION__, endpoint);
>  		return NULL;
>  	}
> +	
> +	ep_desc = find_ep_desc_for(serial, endpoint);
> +	ep_type = ep_desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
> +	switch (ep_type) {
> +	case USB_ENDPOINT_XFER_INT:
> +		ep_type_name = "INT";
> +		usb_fill_int_urb(urb, serial->dev,
> +				 usb_sndintpipe(serial->dev, endpoint) | dir,
> +				 buf, len, callback, ctx,
> +				 ep_desc->bInterval);
> +		break;
> +
> +	case USB_ENDPOINT_XFER_BULK:
> +		ep_type_name = "BULK";
> +		usb_fill_bulk_urb(urb, serial->dev,
> +				  usb_sndbulkpipe(serial->dev, endpoint) | dir,
> +				  buf, len, callback, ctx);
> +		break;
>  
> -		/* Fill URB using supplied data. */
> -	usb_fill_bulk_urb(urb, serial->dev,
> -		      usb_sndbulkpipe(serial->dev, endpoint) | dir,
> -		      buf, len, callback, ctx);
> +	default:
> +		panic("unsupported endpoint type %d", ep_type);

Again, no usb driver should be calling panic().

thanks,

greg k-h

Re: [PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[Rainer Weikusat]

Greg KH <greg@kroah.com> writes:
> On Tue, Jan 02, 2007 at 07:16:54PM +0100, Rainer Weikusat wrote:
>> At least the Keyspan USA-19HS USB-to-serial converter supports
>> two different configurations, one where the input endpoints
>> have interrupt transfer type and one where they are bulk endpoints.
>> The default UHCI configuration uses the interrupt input endpoints.
>> The keyspan driver, OTOH, assumes that the device has only bulk
>> endpoints (all URBs are initialized by calling usb_fill_bulk_urb
>> in keyspan.c/ keyspan_setup_urb).
>
> So, this means that Keyspan changed the USB configuration of this
> device?

No, it means what I have written several times: The UHCI code up to
2.6.17.11 accepted URBs initialized as bulk URBs for interrupt
endpoints, the UHCI code since 2.6.18 doesn't anymore. This is all
somewhat idealized, but these endpoints should be interrupt endpoints
and the driver should initialize its URBs correctly.

> Can you send me the output of 'cat /proc/bus/usb/devices' with this
> keyspan device plugged in?  I'll compare it with the devices I have
> here.

In plain English, this means 'I am fairly convinced that the actual
problem is that you are certainly too stupid to read'.

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=12  MxCh= 0
D:  Ver= 1.10 Cls=ff(vend.) Sub=ff Prot=ff MxPS= 8 #Cfgs=  2
P:  Vendor=06cd ProdID=0121 Rev= 1.00
S:  Manufacturer=Keyspan, a division of InnoSys Inc.
S:  Product=Keyspan USA-19H 
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I:  If#= 0 Alt= 0 #EPs= 5 Cls=ff(vend.) Sub=00 Prot=00 Driver=keyspan
E:  Ad=01(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=81(I) Atr=03(Int.) MxPS=  64 Ivl=1ms
E:  Ad=82(I) Atr=03(Int.) MxPS=  64 Ivl=1ms
C:  #Ifs= 1 Cfg#= 2 Atr=a0 MxPwr=100mA
I:  If#= 0 Alt= 0 #EPs= 5 Cls=ff(vend.) Sub=00 Prot=00 Driver=
E:  Ad=01(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=81(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms

NB: This indicates that the input buffer size (32) is wrong as well.

[...]

>>  /* Helper functions used by keyspan_setup_urbs */
>> +static struct usb_endpoint_descriptor const *
>> +find_ep_desc_for(struct usb_serial const *serial, int endpoint)
>> +{
>> +	struct usb_host_endpoint const *p, *e;
>> +
>> +	p = serial->interface->cur_altsetting->endpoint;
>> +	e = p + serial->interface->cur_altsetting->desc.bNumEndpoints;
>> +	while (p < e && p->desc.bEndpointAddress != endpoint) ++p;
>> +	
>> +	if (unlikely(p == e)) panic("found no endpoint descriptor for "
>> +				    "endpoint %d\n", endpoint);
>
> No need for "unlikely" on such a slow path.

It doesn't hurt and documents that this is the proverbial impossible
condition check.

> Also, panic() should be on the next line for the proper coding
> style.

It is somewhat unreasonable to expect random people to 'just know'
about things that aren't documented.

> And, we don't want to panic() for such a trivial thing.  Just abort the
> probe sequence at most, but never shut down the machine for an odd
> device that we find.

I actually thought about that this morning: Considering the path this
came from, this is not 'an odd device' but rather something like 'kernel
memory corruption' (the 'endpoint' value originally came from the
exact same descriptor).

Re: [PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[Rainer Weikusat]

Rainer Weikusat <rw@semtex.sncag.com> writes:

[...]

>> And, we don't want to panic() for such a trivial thing.  Just abort the
>> probe sequence at most, but never shut down the machine for an odd
>> device that we find.
>
> I actually thought about that this morning: Considering the path this
> came from, this is not 'an odd device' but rather something like 'kernel
> memory corruption' (the 'endpoint' value originally came from the
> exact same descriptor).

This turned out to be wrong: The values are hard-coded in keyspan.h.

[PATCH 2.6.20-rc3] fix for bugzilla #7544 (keyspan USB-to-serial converter)

[Rainer Weikusat]

At least the Keyspan USA-19HS USB-to-serial converter supports
two different configurations, one where the input endpoints
have interrupt transfer type and one where they are bulk endpoints.
The default UHCI configuration uses the interrupt input endpoints.
The keyspan driver, OTOH, assumes that the device has only bulk
endpoints (all URBs are initialized by calling usb_fill_bulk_urb
in keyspan.c/ keyspan_setup_urb). This causes the interval field
of the input URBs to have a value of zero instead of one, which
'accidentally' worked with Linux at least up to 2.6.17.11 but
stopped to with 2.6.18, which changed the UHCI support code handling
URBs for interrupt endpoints. The patch below modifies to driver to
initialize its input URBs either as interrupt or as bulk URBs,
depending on the transfertype contained in the associated endpoint
descriptor (only tested with the default configuration) enabling
the driver to again receive data from the serial converter.

Signed-off-by: Rainer Weikusat <rweikusat@sncag.com>
---

Modified to no longer call panic, but return NULL after having
logged a KERN_WARNING message first.

diff -purN linux-2.6.20-rc3/drivers/usb/serial/keyspan.c linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c
--- linux-2.6.20-rc3/drivers/usb/serial/keyspan.c	2007-01-02 11:10:22.000000000 +0100
+++ linux-2.6.20-rc3-keyspan/drivers/usb/serial/keyspan.c	2007-01-03 15:18:24.000000000 +0100
@@ -1275,11 +1275,32 @@ static int keyspan_fake_startup (struct 
 }
 
 /* Helper functions used by keyspan_setup_urbs */
+static struct usb_endpoint_descriptor const *
+find_ep_desc_for(struct usb_serial const *serial, int endpoint)
+{
+	struct usb_host_endpoint const *p, *e;
+
+	p = serial->interface->cur_altsetting->endpoint;
+	e = p + serial->interface->cur_altsetting->desc.bNumEndpoints;
+	while (p < e && p->desc.bEndpointAddress != endpoint) ++p;
+	
+	if (p == e) {
+		printk(KERN_WARNING "%s - found no endpoint descriptor for "
+		       "endpoint %d\n", __func__, endpoint);
+		return NULL;
+	}
+
+	return &p->desc;
+}
+
 static struct urb *keyspan_setup_urb (struct usb_serial *serial, int endpoint,
 				      int dir, void *ctx, char *buf, int len,
 				      void (*callback)(struct urb *))
 {
 	struct urb *urb;
+	struct usb_endpoint_descriptor const *ep_desc;
+	char const *ep_type_name;
+	unsigned ep_type;
 
 	if (endpoint == -1)
 		return NULL;		/* endpoint not needed */
@@ -1290,12 +1311,34 @@ static struct urb *keyspan_setup_urb (st
 		dbg ("%s - alloc for endpoint %d failed.", __FUNCTION__, endpoint);
 		return NULL;
 	}
+	
+	ep_desc = find_ep_desc_for(serial, endpoint);
+	ep_type = ep_desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
+	switch (ep_type) {
+	case USB_ENDPOINT_XFER_INT:
+		ep_type_name = "INT";
+		usb_fill_int_urb(urb, serial->dev,
+				 usb_sndintpipe(serial->dev, endpoint) | dir,
+				 buf, len, callback, ctx,
+				 ep_desc->bInterval);
+		break;
 
-		/* Fill URB using supplied data. */
-	usb_fill_bulk_urb(urb, serial->dev,
-		      usb_sndbulkpipe(serial->dev, endpoint) | dir,
-		      buf, len, callback, ctx);
+	case USB_ENDPOINT_XFER_BULK:
+		ep_type_name = "BULK";
+		usb_fill_bulk_urb(urb, serial->dev,
+				  usb_sndbulkpipe(serial->dev, endpoint) | dir,
+				  buf, len, callback, ctx);
+		break;
+
+	default:
+		printk(KERN_WARNING "%s - unsupported endpoint type %d\n",
+		       __func__, ep_type);
+		usb_free_urb(urb);
+		return NULL;
+	}
 
+	dbg("%s - using urb %p for %s endpoint %d",
+	    __func__, urb, ep_type_name, endpoint);
 	return urb;
 }