linux-kernel - Re: USB disk speed regression WD Elements - with bisect result 22547c4cc4fe20698a6a85a55b8788859134b8e4

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Message-ID: <Pine.LNX.4.44L0.1707281432270.5102-100000@netrider.rowland.org>
Date:   Fri, 28 Jul 2017 14:33:42 -0400 (EDT)
From:   Alan Stern <stern@...land.harvard.edu>
To:     Zdenek Kabelac <zkabelac@...hat.com>
cc:     USB list <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, <dianders@...omium.org>,
        <linux@...ck-us.net>, <gregkh@...uxfoundation.org>
Subject: Re: USB disk speed regression WD Elements - with bisect result
 22547c4cc4fe20698a6a85a55b8788859134b8e4

On Thu, 27 Jul 2017, Zdenek Kabelac wrote:

> > Zdenek, you check this explanation by commenting out these last two
> > lines at the end of hub_port_connect() in drivers/usb/core/hub.c:
> > 
> > 	if (hcd->driver->relinquish_port && !hub->hdev->parent)
> > 		hcd->driver->relinquish_port(hcd, port1);
> > 
> > That should prevent the connection from being handed over to the UHCI
> > companion, allowing the device to operate at high speed.
> >
> 
> Hi
> 
> Yep - seems this helped - I've dropped revert and commented those 2 lines
> and I've used the very same kernel - and speed was all good:
> 
> usb 2-2: new high-speed USB device number 2 using ehci-pci
> usb 2-2: new high-speed USB device number 3 using ehci-pci
> usb 2-2: New USB device found, idVendor=1058, idProduct=10a8
> usb 2-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> 
> 
> So while I'm not sure if this is final fix for USB - this solution surely 
> solved my WD Element disk attachment issue.

Great!  Here's a real patch to test; I think this will be acceptable if 
it fixes your problem.

Alan Stern



Index: usb-4.x/drivers/usb/core/hub.c
===================================================================
--- usb-4.x.orig/drivers/usb/core/hub.c
+++ usb-4.x/drivers/usb/core/hub.c
@@ -4934,9 +4934,10 @@ loop:
 
 done:
 	hub_port_disable(hub, port1, 1);
-	if (hcd->driver->relinquish_port && !hub->hdev->parent)
-		hcd->driver->relinquish_port(hcd, port1);
-
+	if (hcd->driver->relinquish_port && !hub->hdev->parent) {
+		if (status != -ENOTCONN && status != -ENODEV)
+			hcd->driver->relinquish_port(hcd, port1);
+	}
 }
 
 /* Handle physical or logical connection change events.