From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.valdk.tel (mail.valdk.tel [185.177.150.13]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 10AA827A919 for ; Mon, 22 Sep 2025 14:38:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.177.150.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758551931; cv=none; b=e22whqis8NTOJwIS4kMWAeCdtalK7p9mrPN30Dzzfu39tGt7ChPXww6O/PjDfB1vnTN+3JswwRjwVoCzKeFVh9It7qKzwOLR3GhB6sX93fwtnUgZP+dNoONCQgwBb2ia2vO5ZjMf2syb3CK1mvtH8UQnHJIYKtoyfXJvy3WF9VM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758551931; c=relaxed/simple; bh=gXDGa0Ja1nbIR3EdYfubHxbjsAGNagwBsV9vJyDSPTI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=V8bw7soz9mXH5c4ZceELY4Q/8rC7EgWUmcEWjtg2jAAAFksZm63xGL9x/NiyltH0l94luQRY+X7Rl/I/t8BbZUDCd2zuhHXrD8mqWhJy9x0AfNkT9q9PJBwGcdv1leZ975iIid0t4ufJJZV05+7elEj0afCIbyV456hAMub3a2o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=valdikss.org.ru; spf=pass smtp.mailfrom=valdikss.org.ru; dkim=pass (2048-bit key) header.d=valdikss.org.ru header.i=@valdikss.org.ru header.b=gXE/WmHe; arc=none smtp.client-ip=185.177.150.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=valdikss.org.ru Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=valdikss.org.ru Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=valdikss.org.ru header.i=@valdikss.org.ru header.b="gXE/WmHe" Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 3CB7A1C85B47; Mon, 22 Sep 2025 17:38:38 +0300 (MSK) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=valdikss.org.ru; s=msrv; t=1758551920; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references:autocrypt; bh=tES7qDLJAfWYPSlb391EagAp6pXYYraLKe0foedTVbE=; b=gXE/WmHe9jnXyubMLZg4zS5tOdxCOXMkEkjZnFEuI5foIPadrA80QaDBy1z8Qd28IqFbHS HfIz9srNDVOadeRN9dW39Vu5NP9hoXceRtI6nAMBvgOHOkj4NXjEkTboI79QAIS6wo0iWV Ku+D5MO1fYE0aSsHl8LSlWT2Z7NkKPTsCXsN+0hEgMSUZ5ssDfEFBktmNNDsDSrwCHlt6O zfSx1eJONoqfdRjcJGtVGQ6THzNlkw+KNswQr4IpdFq9pe1M5h0ClgKtV7lKUbFl1zcCqT 9YFMKX51d+VJGwCzoU5Tk0TvI2zn5Ro68nZf4JgGS4GedyrDdrVSKr+baoHXew== Message-ID: Date: Mon, 22 Sep 2025 17:38:38 +0300 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: USB 1.1 Full Speed OHCI slow/high latency To: Alan Stern Cc: Greg KH , linux-usb@vger.kernel.org References: <6017298f-fc03-41c9-b0e3-a74180f4c9a1@rowland.harvard.edu> <2bf5c54e-7dac-4673-a696-e09eb8d459d5@valdikss.org.ru> <7bfaeea9-6eb1-4e49-af8a-77940fdb70fc@rowland.harvard.edu> <9013fce0-6764-49b1-9e54-68e915e12d7c@valdikss.org.ru> <4e83d098-19e8-45aa-94e7-9ef005a0c8ab@rowland.harvard.edu> <6214afad-51c5-46ee-90bc-8625312609a7@valdikss.org.ru> Content-Language: ru, en-US From: ValdikSS Autocrypt: addr=iam@valdikss.org.ru; keydata= xsFNBFPBBkkBEADaww9j8CxzrWLEe+Ho9ZsoTFThdb3NZA3F+vRMoMyvBuy6so9ZQZgCXoz+ Fl8jRF6CYOxoe2iHgC3VisT6T0CivyRQexGQ8bga6vvuXHDfZKt1R6nxPoBJLeyk/dFQk0eC RB81SQ+KHh2AUaTHZueS4m7rWg42gGKr57s+SkyqNYQ3/8sk1pw+p+PmJ0t4B1xRsTmdJEfO RPq+hZp8NfAzmJ4ORWeuopDRRwNmlHrvAqQfsNPwzfKxpT1G4bab4i7JAfZku2Quiiml1cI3 VKVf7FdR+HauuDXECEUh5vsoYR2h8DyfJQLOBi3kbAJpDlkc/C/9atEubOI/blxshxA8Cv/B Gkpf//aAthFEBnbQHFn40jSDIB+QY2SLcpUvSWmu5fKFICyOCDh6K/RQbaeCDQD0L2W6S/65 28EOHALSFqkF6RkAKXBDgT9qEBcQk9CNWkA6HcpsTCcNqEdsIlsHXVaVLQggBvvvJRiWzJY0 QFRxPePnwuHCbnFqpMFP7BQKJyw0+hSo4K3o+zm/+/UZANjHt3S126pScFocEQVIXWVhlDrH 2WuOlRrvfh6cTiD4VKPRiii2EJxA+2tRZzmZiHAeYePq0LD8a0cDkI3/7gtPbMbtgVv2JgpR RZubPS3On+CWbcp9UPqsOnhp6epXPHkcHokGYkLo7xzUBsjENQARAQABzR5WYWxkaWtTUyA8 aWFtQHZhbGRpa3NzLm9yZy5ydT7CwY4EEwEIADgWIQQyKiC9dymZLfa/vWBc1yAu74j3cgUC XqmcAgIbAwULCQgHAgYVCgkICwIEFgIDAQIeAQIXgAAKCRBc1yAu74j3coeKD/9FKRS1CcO6 54uChXmsgtoZjkexjagl2kTXtde5FFPh8Hxub+tNRYIUOYilx5R8pidmKZpVGVlPP3Rzf/Vf tr9YiEhSinQ1waWV5VfU43R5qTo0/I7Ni/vjbboAGULg1bPv0N3lnC5NOEq34WauuXJbfQBl uQpHaG6gGrJyy9hmD0LI9he3JpGItjqicJ4MS3XJO/YmC0UNsvpeuh1Fi6Y+QiJ+AgpYWCgX t8VaoGuinQePLu/Iy+gp5Ie+JTPWt2AKOJylCs6473VdY8m+geJD8yot1uL9mXtRdL8uKXKv 2R4EbEaGVJ0/ls0v0TAohfeFQDdwzGQjk1aBBfdbhDcVmo8slb0ry53AbzO/nxS0pEycvPXu 4pC3pJKCe2pPUuNrCj6Qoijtv0abLN1VocJ2dTsXNgOVHnrEvu032kjTyiGJeQVRgl90Sv/H S/17JHUdTGfoEkTHfivqZOYv/ccYpqh0M1TUE5xgPVnWX13uoBswVZimLKkIPfOxtmQ8Wge2 WlDR/QLwIkGm2b9fBI68lNgBBPv7k16dQL/5ugSDvZNWSThGoYL6i8a3jUJfK8JilIJhsh+D 90MfCAbfiECALc0HOmC4KVRY/zIVMZgwFm0PjNtID0TmWHoFb8rt5sVyLf//Xco4SVk80wPQ /TRnOGM2InosX3l2YoxBrT5Epc7BTQRTwQZJARAAo5h4vuxyV04K1mhVsqoY05kruPrMVptv +uopIlteLfn/9EM0Mn10FJA5WHLWqTT/TuFN+wxkGa1KRnziLpbc/Zq2L/AWthDEb9+pNEjr 3HfT7H71Rjsa3GEYiFgVtPYIQZ8RwuvYv31FgXedHBEXYrhm+kKh8d0A76nHc9jUJJKZyja6 Wtz2SP6QFYnlf9rCXMiyB5d4l0xZgbWWok8Fol9tZbRte+Lwn1QtmpNhtDbEb28I3W3VVYnk LYtWaTWo8udVyngjGCM3zLV4VMVDZi77Fycel1UGNQTCyjeNuhRyL6Ms9IOGVcKWURJWXbzZ BSBzqc/PGvRi+A1ytJtEKWyZHrx1Yf5va3vDqRKYBxhOtnf5Fh+nd0e37V8yUb3ofLXgG30A mR14xobjaF3ziS0D5w03611YpPlIKwWogQeOVHlinYySIlQtKEsx5pQYgdQ0PzFy53xUsx47 EVLeRKw5PG4uyH79mgyNEFhn+tGMUlSOYDngIIiSm0k0v8+hyP+T1XLDy4Uo4IQXTdRZ5/tN AIlhNEftQyvI3wZC9IZoiZLOgw7qsCrBJ5VMwweZzi94PYCjQPUACr8yF5taJ1lQKuUfltR1 iGYb6Vdf9hnNs5E0Flo2WZfaywfMjAh5I9GhUKRC6BgfpYtmgFbGzDbhr1idSH3NbMUD3wg+ TP0AEQEAAcLBXwQYAQIACQUCU8EGSQIbDAAKCRBc1yAu74j3coMhD/wJiHIe7DuvhWr39An/ yA9zAqNTvQEdm3vUIw5UQjqn45IOnn/R+leps31hVrROSzhpXeeGtOh17+jjt2hbw3KRrgYi V+qWiNBx7Ux3UOGOCqeAhnztTn0uHJUiarEYPhTm6K4tJB1Ob6RG7+ftIBrD/fUCCDWIEOT8 7Q0xj0IH94Gxo1s+iRrRnNwyQXa821EzqqZgsv4fKvQmGtGX3sPDrXV057tNaF7jmrWBkJZt heU8LaH4EAmcJc1k30k1ql8T4kXO1qKlJvMdLji39fq7kWA6xdgpjwI5EHaIAj6R2T48iWVw Fu2vLSZPR983j+Eh7VwGnvAh9Tj19uXYPUBqgAzIYDWWOGiM2FsezzWQ8rADAcXNMyV+/a4S Kcur0yPLYbL5mP5TWLb4ucCF/6eDgcNG6u1U1kKslRXzVc/3l8ZoX4Djs0nIyjwsbhuwiL8x rvpQq1VvOlkpyypS8w5t4U12yEeO2XKiHUcnCdFCk5yd1Vg77EulqY06nCJgaVMDSxLowtqL 6V6G7SxBEhcsR4fmpY7nj4GoymEGom3dLqe2JjTpVTJcuuFleHHI/lbcBa5hiN8a7+c8A9K2 FzgxriVWpfwm0XovNBjugipYItle3p/18YCjVnUoXEsgrjUOgAaQ2RVHJzRz07tKX1DBhFRD OEcVmRU/pw5/zoQyQg== In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 On 22.09.2025 5:16 PM, Alan Stern wrote: > On Mon, Sep 22, 2025 at 02:11:43AM +0300, ValdikSS wrote: >> Alan, Greg, I found the reason for 1 ms delay: it is artificial, added in >> v2.5.21 as a possible race condition fix: > > Good work tracking that down! > >> I removed "+ 1" and it removed that 1ms delay. Doesn't seem to break >> anything in my setup. UHCI code doesn't seem to have any similar delays. >> >> Could it be relevant only for hardware of its era? If I add "no +1" code >> quirk as a module option, disabled by default, does it sounds sane to you? > > I'm not sure that there is any OHCI hardware from later than that era. > But regardless... > > Module options are frowned upon these days. Instead you could add a > sysfs (or even debugfs) attribute file for controlling that "+ 1". I just implemented another approach: do not unlink the ED right away, instead mark it IDLE and unlink only if no consecutive transfers are performed after the timeout. This still preserves one-frame delay while unlinking, should be safe. Please take a look if you have free time. I'm no kernel developer by any means :)