From: Pete Zaitcev <zaitcev@redhat.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jeremy Figgins <kernel@jeremyfiggins.com>,
gregkh@linuxfoundation.org, linux-usb@vger.kernel.org
Subject: Re: [PATCH] USB: usblp: add USBLP_QUIRK_NO_SET_INTF flag
Date: Thu, 21 Jan 2021 17:02:49 -0600 [thread overview]
Message-ID: <20210121170249.4081af4c@suzdal.zaitcev.lan> (raw)
In-Reply-To: <20210121192929.GA12502@rowland.harvard.edu>
On Thu, 21 Jan 2021 14:29:29 -0500
Alan Stern <stern@rowland.harvard.edu> wrote:
> > I'm also concerned about regressions. This is a legacy class driver,
> > only used where CUPS is not applicable, mostly with truly ancient
> > devices. So yes, setting a zero altsetting after enumeration should
> > be unnecessary. But you never know with the old firmware.
> How about skipping the call whenever the interface has only one
> altsetting?
Do you mean when it's only one and not equal to zero?
BTW, one other thing bothers me. Jeremy confirmed that my patch
worked, which skips the call when USB_QUIRK_NO_SET_INTF is set.
But if we look into drivers/usb/core/message.c, the control
exchange to set the altsetting is skipped in that case anyway.
So, usblp was calling usb_set_protocol, the suspect control was
skipped, but something else caused a problem. Could it be the
attempt to clear halt that triggered the problem?
-- Pete
next prev parent reply other threads:[~2021-01-21 23:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-17 21:36 [PATCH] USB: usblp: add USBLP_QUIRK_NO_SET_INTF flag Jeremy Figgins
2021-01-18 5:44 ` Pete Zaitcev
2021-01-18 16:31 ` Alan Stern
2021-01-18 16:43 ` Michael Sweet
2021-01-19 0:01 ` Jeremy Figgins
2021-01-21 19:21 ` Pete Zaitcev
2021-01-21 19:19 ` Pete Zaitcev
2021-01-21 19:29 ` Alan Stern
2021-01-21 23:02 ` Pete Zaitcev [this message]
2021-01-22 1:06 ` Jeremy Figgins
2021-01-22 16:22 ` Alan Stern
2021-01-23 18:46 ` Jeremy Figgins
2021-01-23 21:33 ` Alan Stern
2021-01-22 16:20 ` Alan Stern
2021-01-18 9:02 ` Sergei Shtylyov
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