Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755987AbcKCI0O (ORCPT ); Thu, 3 Nov 2016 04:26:14 -0400 Received: from up.free-electrons.com ([163.172.77.33]:58949 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753831AbcKCI0L (ORCPT ); Thu, 3 Nov 2016 04:26:11 -0400 Date: Thu, 3 Nov 2016 09:26:08 +0100 From: Maxime Ripard To: Chen-Yu Tsai Cc: Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , Rob Herring , Mark Rutland , alsa-devel@alsa-project.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-sunxi@googlegroups.com, Vinod Koul Subject: Re: [PATCH v2 04/14] ASoC: sun4i-codec: Increase DMA max burst to 8 Message-ID: <20161103082608.4e27avywl5fmozt2@lukather> References: <20161103075556.29018-1-wens@csie.org> <20161103075556.29018-5-wens@csie.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="pivqiv7xd34p5yoj" Content-Disposition: inline In-Reply-To: <20161103075556.29018-5-wens@csie.org> User-Agent: Mutt/1.6.2-neo (2016-08-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2523 Lines: 64 --pivqiv7xd34p5yoj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Nov 03, 2016 at 03:55:46PM +0800, Chen-Yu Tsai wrote: > According to the DMA engine API documentation, maxburst denotes the > largest possible size of a single transfer, so as not to overflow > destination FIFOs as explained in this excerpt from dmaengine.h >=20 > * @src_maxburst: the maximum number of words (note: words, as in > * units of the src_addr_width member, not bytes) that can be sent > * in one burst to the device. Typically something like half the > * FIFO depth on I/O peripherals so you don't overflow it. This > * may or may not be applicable on memory sources. > * @dst_maxburst: same as src_maxburst but for destination target > * mutatis mutandis. >=20 > The TX FIFO is 64 samples deep for stereo, and the RX FIFO is 16 > samples deep. So maxburst could be 32 and 8 for TX and RX respectively. >=20 > Unfortunately the sunxi DMA controller driver takes maxburst as > the requested burst size, rather than a limit, and returns an error > for unsupported values. The original value was 4, but some later > SoCs do not officially support this burst size. >=20 > This patch increases maxburst on the TX side to 8, which is supported > by all variants of the sunxi DMA controller. >=20 > Cc: Vinod Koul > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard Thanks, Maxime --=20 Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com --pivqiv7xd34p5yoj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJYGvSgAAoJEBx+YmzsjxAg/gYP/24c/bpYq74OmJLKJ0QKAO47 gVJ/SMX2Z3epM4dai9g/Xpv8YtUkvHu7Oe7NWuYxLSa8MQH+XvQduC4n937Ks329 4FArj8mCygedv3pIQi3eDCli7B64RgoVb8h7XPqVdJ7fIki/8xr2IA6bDd9ZAT1x r9V+fXrjHNNYMPWWlu1WVY49lGZysDzg3htJEQ3kTsMvNoRhV7Wd4n8F8fIlkZZS uLQ7MLi5nEouDBPMwdw2uKzhySvvxXKNvxQkK8Cz2xUfbQ5/RoRSdmhA3PJI//Ae C2TTXuvAKWKLlSaXRj/u/r2v37EkiaMvAq+vrCT/1TOWSWguCDgNIDr23SPpFfWX vktjeVl+crg+LC6d40jIx8p3VWOdl8aO5Xil9hksuDQX3abVi675+Wo9/t5t1N4/ n5IWZGw12VFwX1cOJSQJ0J2p604RYcB8sNq9jEo66VOV6SCyohSYgcwFtRDNQkuU 7n1/lvQ9HJTsnbX0m6XVzfXErrvsUvt/CwBsSJzvf6eeYj0RkbpBQ6dPqIrbaiZf TnYXOKl2x+ZQLsiO0Tanw+1RKWi0gvA/2FfbTMACYHsTG+cV1iOYK2asGtGMZdtU pqkcyqlCZ94I3GlgkzVvsglmJXYi8KdKsgCFPIlr4etHRgGGdZBRU6sYIZ4tYeiD Dq6BcDtO1oWudabQLPI5 =PqIS -----END PGP SIGNATURE----- --pivqiv7xd34p5yoj--