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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78599C28CF5 for ; Wed, 26 Jan 2022 18:31:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235523AbiAZSbm (ORCPT ); Wed, 26 Jan 2022 13:31:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231779AbiAZSbm (ORCPT ); Wed, 26 Jan 2022 13:31:42 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1D73C06161C for ; Wed, 26 Jan 2022 10:31:41 -0800 (PST) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nCn51-0003Kn-GI; Wed, 26 Jan 2022 19:31:39 +0100 Received: from mgr by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1nCn50-0005Ay-3G; Wed, 26 Jan 2022 19:31:38 +0100 Date: Wed, 26 Jan 2022 19:31:38 +0100 From: Michael Grzeschik To: Alan Stern Cc: kieran.bingham@ideasonboard.com, linux-usb@vger.kernel.org, balbi@kernel.org, paul.elder@ideasonboard.com, laurent.pinchart@ideasonboard.com, kernel@pengutronix.de, nicolas@ndufresne.ca Subject: Re: [PATCH] dummy_hcd: add isoc support Message-ID: <20220126183138.GB6506@pengutronix.de> References: <164154749753.1224575.16682991529695492259@Monstersaurus> <20220126132249.2133168-1-m.grzeschik@pengutronix.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="v9Ux+11Zm5mwPlX6" Content-Disposition: inline In-Reply-To: X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 19:25:00 up 47 days, 3:10, 67 users, load average: 0.13, 0.09, 0.10 User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: mgr@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-usb@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org --v9Ux+11Zm5mwPlX6 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 26, 2022 at 11:09:23AM -0500, Alan Stern wrote: >On Wed, Jan 26, 2022 at 02:22:49PM +0100, Michael Grzeschik wrote: >> With this patch, the dummy_hcd gains first support for isoc transfers. >> It will complete the whole urb with all packages. > >"packets", not "packages". Right. >> Even if the gadget >> side did not enqueue any request, the urb will be handled. >> >> Signed-off-by: Michael Grzeschik > >I don't like this idea. If support for isochronous transfers is added, >it should be done correctly. That is, the implementation should support >scheduling of transfers, periodic bandwidth reservation, high-bandwidth >transfers, and so on. > >The whole point of dummy-hcd is to emulate a real host controller as >closely as possible. Real isochronous transfers do not complete all at >once. I agree, that whole isoc support needs proper improvement. I could/should have added RFC to the patch. As the whole intention of this code, for now, is to validate the gadget/uvc configfs patchseries mentioned in the the comments. With this patch, it is at least possible to get the gadget running on dummy_hcd and try out the "non-isoc dependent" parts, that are actually changed, in the mentioned series. The validation of the payload path, actually using the mentioned isoc endpoints, is left to the developer who implements the missing parts you mentioned above. Michael --=20 Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --v9Ux+11Zm5mwPlX6 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEElXvEUs6VPX6mDPT8C+njFXoeLGQFAmHxk4YACgkQC+njFXoe LGQm9g/+P+PNtCcMwI9lbY/qpjyjuBzYOBg50kLJCBK0w8dFSu6sY2jkq/ZjAJRx xXXrfLC1LVtnQPUsmm+d9JDtA4cao2Idd0MI/MDuULngCNXf5oG77hw/ln7ZpSyd Pxxf8z4rMi97+/p4vhLdToyTV4Wlx4feVD3xFizcnhJkNIlI7++RZy1Uv+IzDx5H siQxBjwSaXZlgAlBxbGVDeYdP6+cjG3V+rGR5zuz0c5VZuWzn8sThNwomsvV4s2/ LMLxIX+J0GgookxKixJgcOmTzHRCReOeMrxOivjfF5s6Pd1565DxfR20SUwurUDY uO+lKqSMHz9DxXU6BH7kaKquyXR+bM0ufaC1ykpZTU1IQtxys8zdCXdgaX9GX5E6 urFD7dFQDU34VvqQehU8oSpLwac9s2UvrJeBvkjOxxMgBHy/Q4UZsyUkgKn2BhNf 2k8QjsoN45CPx8L2kw7MSziCU2kOKfNDhLquV2354CnMkWqX0oUtsxJvUvNLN635 FHkeYmyfET23YS+9O1PxHjNRWZZZjX98A6CHY2NVEFx5oDNWkK89z8kBYjvCaY3N Z+8ektuweiDHrOeT/trzIDmc72wZg78jLBZktoUafHvq0/Nq7y+JOOsAI4FStFSB +hNozHSGIRq7GEFO/UAqi1AFEyGEm4/uwIUBtdSgSnX1MdueVqM= =veNB -----END PGP SIGNATURE----- --v9Ux+11Zm5mwPlX6--