From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Echtler Subject: [sur40] videobuf2 and/or DMA? Date: Mon, 08 Dec 2014 08:50:46 +0100 Message-ID: <54855856.3070207@butterbrot.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="4n4TEAQmhDt2rbHHq201twGu3g3gFeEC5" Return-path: Received: from butterbrot.org ([176.9.106.16]:40980 "EHLO butterbrot.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751007AbaLHH5z (ORCPT ); Mon, 8 Dec 2014 02:57:55 -0500 Received: from [192.168.178.30] (unknown [95.90.212.125]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by butterbrot.org (Postfix) with ESMTPSA id 803E95C00CDA for ; Mon, 8 Dec 2014 08:50:47 +0100 (CET) Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: linux-input This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --4n4TEAQmhDt2rbHHq201twGu3g3gFeEC5 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hello everyone, I'm preparing to finally add support for the raw sensor video stream to my driver for the SUR40 touchscreen. However, after an extensive amount of Googling, I'm still not clear on the relationship between DMA transfers, the USB core and the videobuf2 framework. Specifically, I'd like to know: - Can I always use DMA on the USB side (for bulk transfers), or does this in any way require support from the USB device's hardware? (I'm guessing no, but a definite answer would be great.) - Regardless of the USB side of things, can I use the videobuf2 framework without _having_ to use DMA? That way, I could get a basic driver running without DMA and switch later when it's convenient and/or the speedup is justified. Thanks & best regards, Florian --=20 SENT FROM MY DEC VT50 TERMINAL --4n4TEAQmhDt2rbHHq201twGu3g3gFeEC5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlSFWFYACgkQ7CzyshGvatgPUwCfVtURNd1nI3qKuwp1/IoRT0QX 3e4AoJq3pJ8PxACnOjb9G/Bfv0jzAbKc =61c9 -----END PGP SIGNATURE----- --4n4TEAQmhDt2rbHHq201twGu3g3gFeEC5--