From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9140BC2D0DC for ; Thu, 2 Jan 2020 09:08:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E77921655 for ; Thu, 2 Jan 2020 09:08:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727861AbgABJIr convert rfc822-to-8bit (ORCPT ); Thu, 2 Jan 2020 04:08:47 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([146.101.78.151]:42184 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727842AbgABJIr (ORCPT ); Thu, 2 Jan 2020 04:08:47 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-1-pIIvPwufNpOpNDvQYajY9g-1; Thu, 02 Jan 2020 09:08:43 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Thu, 2 Jan 2020 09:08:43 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Thu, 2 Jan 2020 09:08:43 +0000 From: David Laight To: 'Tejas Joglekar' , "linux-usb@vger.kernel.org" , Mathias Nyman CC: John Youn Subject: RE: [RFC PATCH 1/4] usb: xhci: Synopsys xHC consolidate TRBs Thread-Topic: [RFC PATCH 1/4] usb: xhci: Synopsys xHC consolidate TRBs Thread-Index: AQHVtzrjB/1wrvW8bUqvSt/jrU3hbqfXKWiw Date: Thu, 2 Jan 2020 09:08:42 +0000 Message-ID: <2c11ec9e579f4ead946d759aa4d7ed3e@AcuMS.aculab.com> References: <08d08f2fd6da50e382852d014a08e371f2182382.1576848504.git.joglekar@synopsys.com> In-Reply-To: <08d08f2fd6da50e382852d014a08e371f2182382.1576848504.git.joglekar@synopsys.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: pIIvPwufNpOpNDvQYajY9g-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org From: Tejas Joglekar > Sent: 20 December 2019 13:39 > > The Synopsys xHC has an internal TRB cache of size TRB_CACHE_SIZE for > each endpoint. The default value for TRB_CACHE_SIZE is 16 for SS and 8 > for HS. The controller loads and updates the TRB cache from the transfer > ring in system memory whenever the driver issues a start transfer or > update transfer command. > > For chained TRBs, the Synopsys xHC requires that the total amount of > bytes for all TRBs loaded in the TRB cache be greater than or equal to 1 > MPS. Or the chain ends within the TRB cache (with a last TRB). > > If this requirement is not met, the controller will not be able to send > or receive a packet and it will hang causing a driver timeout and error. This ought to be raised with Synopsys and they should be remake their silicon to meet the XHCI standard and then offer to fix all the boards that contain their broken version :-) David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)