From: Alan Stern <stern@rowland.harvard.edu>
To: Dylan Robinson <dylan_robinson@motu.com>
Cc: mathias.nyman@linux.intel.com, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
mathias.nyman@intel.com, Michal Pecio <michal.pecio@gmail.com>,
nick83ola <nick83ola@gmail.com>,
niklas.neronin@linux.intel.com
Subject: Re: [PATCH 1/2] usb: xhci: fix isoc silent reschedule creating stream gap on CFC controllers
Date: Wed, 6 May 2026 22:25:01 -0400 [thread overview]
Message-ID: <3ea05812-e63a-4562-9ec3-159244b571b4@rowland.harvard.edu> (raw)
In-Reply-To: <CA+Df+jdFEGGZyceFH_5LRSQjwGa1WCtd79DK1Lywvdw+pkX6fw@mail.gmail.com>
On Wed, May 06, 2026 at 03:55:27PM -0400, Dylan Robinson wrote:
> On 5/5/26 16:32, Mathias Nyman wrote:
> > Agreed, setting start_frame to start_frame_id + 1 would only make sense for the very first URB, otherwise we create glitches.
> >
> > Looks like the whole start_frame_id calculation is incorrect.
>
> I'd also like to call attention to the fact that index in
> xhci_get_isoc_frame_id() refers to the isoc packet index within the
> URB, not the position of the transfer in the overall stream. A driver
> could (although probably shouldn't) submit multiple URBs, each
> describing less than a microframe's worth of transfers, ...
How can this happen? The only way for an URB to describe less than a
microframe's worth of transactions is if it describes no transactions at
all.
Did you mean less than a frame's worth?
Alan Stern
next prev parent reply other threads:[~2026-05-07 2:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-06 19:55 [PATCH 1/2] usb: xhci: fix isoc silent reschedule creating stream gap on CFC controllers Dylan Robinson
2026-05-07 2:25 ` Alan Stern [this message]
2026-05-07 9:59 ` Dylan Robinson
2026-05-07 12:12 ` Mathias Nyman
2026-05-07 16:58 ` Dylan Robinson
-- strict thread matches above, loose matches on Subject: below --
2026-05-04 23:31 [PATCH 0/2] xhci: Fix isochronous scheduling gaps " Nicola Lunghi
2026-05-04 23:31 ` [PATCH 1/2] usb: xhci: fix isoc silent reschedule creating stream gap " Nicola Lunghi
2026-05-05 13:32 ` Mathias Nyman
2026-05-08 16:56 ` Michal Pecio
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