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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C3798C432C0 for ; Mon, 2 Dec 2019 08:54:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A40362245C for ; Mon, 2 Dec 2019 08:54:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726428AbfLBIyv (ORCPT ); Mon, 2 Dec 2019 03:54:51 -0500 Received: from sauhun.de ([88.99.104.3]:42010 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726350AbfLBIyu (ORCPT ); Mon, 2 Dec 2019 03:54:50 -0500 Received: from localhost (p54B3363C.dip0.t-ipconnect.de [84.179.54.60]) by pokefinder.org (Postfix) with ESMTPSA id B15772C04A3; Mon, 2 Dec 2019 09:54:48 +0100 (CET) Date: Mon, 2 Dec 2019 09:54:48 +0100 From: Wolfram Sang To: Yoshihiro Shimoda Cc: "linux-renesas-soc@vger.kernel.org" Subject: Re: [PATCH RFC 4/4] mmc: host: renesas_sdhi_sys_dmac: Set dma_buswidth value to 32 byte Message-ID: <20191202085448.GD1266@kunai> References: <1574403231-18512-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> <1574403231-18512-5-git-send-email-yoshihiro.shimoda.uh@renesas.com> <20191128210728.GA864@kunai> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="LKTjZJSUETSlgu2t" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org --LKTjZJSUETSlgu2t Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Shimoda-san, > > 1) can't we set dma_priv->dma_buswidth at runtime when we know what the > > card is capable of? Either DMA_SLAVE_BUSWIDTH_32_BYTES or > > DMA_SLAVE_BUSWIDTH_4_BYTES? Then we don't need to fallback to PIO. > > AFAIS, we only Gen2 sets .dma_buswidth in of_data, so we could even > > remove it from of_data entirely? >=20 > As I replied to Ulrich-san on other email thread, for now, rcar-dmac has = a limitation > on dmaengine_slave_config(), we should not call it at runtime. But, I don= 't think > any sd card have such a limitation. In other words, if rcar-dmac doesn't = have > the limitation, I think we can change the buswidth at runtime and then we= can > remove the .dma_buswidth from of_data. So, that I understand correctly: The DMAC limitation is because of the driver and not because of the HW? If so, is it hard/planned to be fixed? > I also grepped in drivers/dma, and all dmaengine drivers except Renesas r= elated > SoCs don't support DMA_SLAVE_BUSWIDTH_32_BYTES. So, I think no driver uses > the 32 bytes on mmc/hosts :) Wow, we are bleeding edge with this? :) Thanks, Wolfram --LKTjZJSUETSlgu2t Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl3k0VcACgkQFA3kzBSg KbZoNg//ezhUoYdzJAmhqBtU+A8clC0LGkYkhcHMACjFXxbNrnB4/S2THO+pWP3b SKdHfaQRflbhEWBz+QnuUWlWlgxhTI+nbst86rrXlMbk/deTzkt8CMkXNVQApWIF s0lFZIQTHa+YvmuLL7y3qmfLLAo7Epo1w0VLfxhjtK9EajZ1ryRjtyTWRVIEcy0o FTh59GSnZ+ykePlRBQL9p/Lq35D7ZX6++967Ig/eqCVBNrfDWmWptKOpkpnho8lk TDs8wK4YBzrZa8/PGbXvKDdAU4Y3a/91/A2udBUUizQYnPOJYsHYzapDl0oisIPe Kuvmu94Rg2/Nt28wncVE0Hd6xjL5mRh3BEBfxpkFCRL5gz3kB2/QjQsJfLdNsCuL TwgQUmX3lDWs7Gm8ODDuJtwpH7tCavQhvTwmNzw7UDMPWaMpcFHSVQP13VkXjShj N+5MBlefKOMMxHNHd/SraJ8tsdRdj204plAYcrnbUCZbdOUaVnafLy4EAyXlVyVm WzpA1H6G/u8lvlGoL3UJbii6rpwzZlsL+ulsExKdBbzRdOGnGCinJXg4fUF5HmUF IdQ4vugPST9SSSN6MQ7KEBOtYnLdR8pv1EQLZRoMVPkw+bkoa31WyMpPTjC4CTiB 0VFtMRJlLBNk4dOXodIpTMH/bNvDUBSYZp0JibBQeznd3I84KoQ= =6+7V -----END PGP SIGNATURE----- --LKTjZJSUETSlgu2t--