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[209.132.180.67]) by mx.google.com with ESMTP id h2-v6si10449948plh.339.2018.07.30.08.35.46; Mon, 30 Jul 2018 08:36:01 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@sirena.org.uk header.s=20170815-heliosphere header.b=qOgrfTDZ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726888AbeG3RKV (ORCPT + 99 others); Mon, 30 Jul 2018 13:10:21 -0400 Received: from heliosphere.sirena.org.uk ([172.104.155.198]:54468 "EHLO heliosphere.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726762AbeG3RKV (ORCPT ); Mon, 30 Jul 2018 13:10:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sirena.org.uk; s=20170815-heliosphere; h=In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Bbs/D1socRe45v1LI1/Ta0Dxb+3m3ibmjtplzMcPPfI=; b=qOgrfTDZMu7EVRCFEmW1yKYgo 0E1MaO+Rkt5+wNIMHbWTVbianeVNwiJZPseIRTi/+Un5KTGtK+r/DuHwl2WUQRV4GealG4PlrmfdW XoxOjXxf6e2Y+xpSdsp2swK8xH92ci4wHwq9mWMMHoUydWT4MQoq9LVoH/dhgRBUP0Fuw=; Received: from cpc102320-sgyl38-2-0-cust46.18-2.cable.virginm.net ([82.37.168.47] helo=debutante.sirena.org.uk) by heliosphere.sirena.org.uk with esmtpa (Exim 4.89) (envelope-from ) id 1fkAC6-0005X7-FT; Mon, 30 Jul 2018 15:34:46 +0000 Received: by debutante.sirena.org.uk (Postfix, from userid 1000) id 336051124216; Mon, 30 Jul 2018 16:34:46 +0100 (BST) Date: Mon, 30 Jul 2018 16:34:46 +0100 From: Mark Brown To: Andreas =?iso-8859-1?Q?F=E4rber?= Cc: linux-mips@linux-mips.org, Ralf Baechle , Paul Burton , James Hogan , linux-kernel@vger.kernel.org, Ionela Voinescu , linux-spi@vger.kernel.org Subject: Re: [PATCH 13/15] spi: img-spfi: RX maximum burst size for DMA is 8 Message-ID: <20180730153446.GN5789@sirena.org.uk> References: <20180722212010.3979-1-afaerber@suse.de> <20180722212010.3979-14-afaerber@suse.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="GEn4szYucjS2InE7" Content-Disposition: inline In-Reply-To: <20180722212010.3979-14-afaerber@suse.de> X-Cookie: But they went to MARS around 1953!! User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --GEn4szYucjS2InE7 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Jul 22, 2018 at 11:20:08PM +0200, Andreas F=E4rber wrote: > From: Ionela Voinescu >=20 > The depth of the FIFOs is 16 bytes. The DMA request line is tied > to the half full/empty (depending on the use of the TX or RX FIFO) > threshold. For the TX FIFO, if you set a burst size of 8 (equal to > half the depth) the first burst goes into FIFO without any issues, > but due the latency involved (the time the data leaves the DMA > engine to the time it arrives at the FIFO), the DMA might trigger > another burst of 8. But given that there is no space for 2 additonal > bursts of 8, this would result in a failure. Therefore, we have to > keep the burst size for TX to 4 to accomodate for an extra burst. This seems like something that should be sent as a bug fix - doesn't it fix anything? If it is a fix then it should've gone at the start of the series so it's got no dependencies and could be sent to Linus for the current release. > While here, move the burst size setting outside of the if/else branches > as they have the same value for both 8 and 32 bit data widths. Though this refactoring probably less so. --GEn4szYucjS2InE7 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAltfMBUACgkQJNaLcl1U h9A8fQf8DSTyUdJz3ii5KeP1L+ww020+hxhlkv6pI/+iToSlsTzqljvcJqKoodUd I3GKROAn1z+oIhdlLTrzq6PbLbGd7/VIK6GR5RG5Y7hRuOBy4dPhvG896r/24s8s kKZHboyXoKWh841UylnNOKFs7NVSrZJ1B9ru3XczSPD62ge8mYmkuhrzAYBuNdhW lqiz+ADaMgakHv4cOL5vJPkJFgqGYdHsAtiCY59qfl2huKrhDs8oeFODFlLGB+DK O8BIwugd0spRSWKIo/cZIqguWPjHn+RT2wUZzWRt1yNnPpXioU2EjHGs3CzVpsfQ 8fXKQOaliO6vHri/IWdvMiSHi+t0ug== =NzDz -----END PGP SIGNATURE----- --GEn4szYucjS2InE7--