diff mbox

[U-Boot,v4,2/2] usb: musb: Fix hub port setting for SPLIT transactions

Message ID 1450743664-8612-2-git-send-email-stefan.bruens@rwth-aachen.de
State Accepted
Delegated to: Marek Vasut
Headers show

Commit Message

Stefan Brüns Dec. 22, 2015, 12:21 a.m. UTC 
The ifdef'ed Linux kernel code uses the 1 based port number, whereas U-Boot
puts a 0 based port number into the register. The reason the 0 based port
number apparently works can probably be taken from the USB 2.0 spec:

8.4.2.2 Start-Split Transaction Token
... The host must correctly set the port field for single and multiple TT
hub implementations. A single TT hub implementation *may ignore* the port
field.

Actually, as far as I understand, a multi TT hub defaults to single TT
(bAlternateSetting: 0) until switched via SetInterface, so even "port 42"
would work.

The change was verified by hardcoding the port number to a wrong value,
SPLIT transactions kept working (although using a DWC2 instead of MUSB).
Tested hubs are the RPi onboard SMC9514 and an external "05e3:0608
Genesys Logic, Inc. USB-2.0 4-Port HUB". The former is a multi TT hub,
the latter single TT only.

Addendum: Tested on sunxi/MUSB by Hans de Goede

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
---
v2: - renamed function to usb_find_usb2_hub_address_port()
    - put musb port numbering change into separate patch
v3: - do one assignment per line
v4: - fix error in musb code (udev => urb->dev)
    - added Reviewed-by: et al

 drivers/usb/musb-new/musb_host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Marek Vasut Dec. 22, 2015, 12:24 a.m. UTC | #1 
On Tuesday, December 22, 2015 at 01:21:04 AM, Stefan Brüns wrote:
> The ifdef'ed Linux kernel code uses the 1 based port number, whereas U-Boot
> puts a 0 based port number into the register. The reason the 0 based port
> number apparently works can probably be taken from the USB 2.0 spec:
> 
> 8.4.2.2 Start-Split Transaction Token
> ... The host must correctly set the port field for single and multiple TT
> hub implementations. A single TT hub implementation *may ignore* the port
> field.
> 
> Actually, as far as I understand, a multi TT hub defaults to single TT
> (bAlternateSetting: 0) until switched via SetInterface, so even "port 42"
> would work.
> 
> The change was verified by hardcoding the port number to a wrong value,
> SPLIT transactions kept working (although using a DWC2 instead of MUSB).
> Tested hubs are the RPi onboard SMC9514 and an external "05e3:0608
> Genesys Logic, Inc. USB-2.0 4-Port HUB". The former is a multi TT hub,
> the latter single TT only.
> 
> Addendum: Tested on sunxi/MUSB by Hans de Goede
> 
> Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Tested-by: Hans de Goede <hdegoede@redhat.com>

Applied both, thanks!

Best regards,
Marek Vasut
diff mbox

Patch

diff --git a/drivers/usb/musb-new/musb_host.c b/drivers/usb/musb-new/musb_host.c
index 70f8a99..2515447 100644
--- a/drivers/usb/musb-new/musb_host.c
+++ b/drivers/usb/musb-new/musb_host.c
@@ -2098,7 +2098,7 @@  int musb_urb_enqueue(
 							       &hubaddr,
 							       &portnr);
 				qh->h_addr_reg = hubaddr;
-				qh->h_port_reg = portnr - 1;
+				qh->h_port_reg = portnr;
 			}
 #endif
 		}