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Wed, 06 May 2026 19:25:04 -0700 (PDT) Date: Wed, 6 May 2026 22:25:01 -0400 From: Alan Stern To: Dylan Robinson 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 , nick83ola , niklas.neronin@linux.intel.com Subject: Re: [PATCH 1/2] usb: xhci: fix isoc silent reschedule creating stream gap on CFC controllers Message-ID: <3ea05812-e63a-4562-9ec3-159244b571b4@rowland.harvard.edu> References: Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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