From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: Bernhard Gebetsberger <bernhard.gebetsberger@gmx.at>
Cc: Mathias Nyman <mathias.nyman@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] xhci: Don't use soft retry if slot id > 0
Date: Mon, 14 Oct 2019 11:06:40 +0300 [thread overview]
Message-ID: <84476602-7551-b667-9803-55016e477b02@linux.intel.com> (raw)
In-Reply-To: <20191013003313.3497-1-bernhard.gebetsberger@gmx.at>
On 13.10.2019 3.33, Bernhard Gebetsberger wrote:
> According to the xhci specification(chapter 4.6.8.1) soft retry
> shouldn't be used if the slot id is higher than 0. Currently some usb
> devices break on some systems because soft retry is being used when
> there is a transaction error, without checking the slot id.
>
That is not correct
Specs say that soft retry should not be used if we are dealing with a
FS/LS device behind a HS hub, this can be checked from the "TT Hub Slot ID"
field in the slot context, which we do.
In xhci all devices have a slot id, so this change would prevent
soft retry almost completely.
Specs 4.6.8.1:
"Soft Retry attempts shall not be performed if the device is behind a
TT in a HS Hub (i.e. TT Hub Slot ID > ‘0’)."
-Mathias
next prev parent reply other threads:[~2019-10-14 8:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-13 0:33 [PATCH] xhci: Don't use soft retry if slot id > 0 Bernhard Gebetsberger
2019-10-14 8:06 ` Mathias Nyman [this message]
2019-10-14 9:17 ` Bernhard Gebetsberger
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