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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9B19EC43334 for ; Tue, 5 Jul 2022 13:05:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=MsYrczWGObT3IO3Yq1ahIcD/b548AaXRPXzIgqfvGCY=; b=pHQXrQXvQ4ZEks 9k2/gFp5eU6GWP0+TjrQRUjBBRLKtmA7P1zPhzjmP9KrIFkUBBdNH6jqbli/EGH/qmTe5RdurFTZM DGneDNyunZtrLj9r1vZ5sBYvDPpZgEYIC/fWeZKyag7/ZLHQj5DJEDNyGex9TmCEZ1f4n095lsrSi I5rLFUOv98uEEOnxnVxcfUBZle7QnFao04FOBpq1k829ES0ZEEOl6vqUlj+BD22cKr5tuRy4vMxHY yIA3fEwssXb6iRz0RbaOAnf4cDrYJ2gYZBZKbHzZZKU127KoBmybrpmQ/VYdoov+Jwh1+9nR0hTLQ 5AOzax7yNdtHf1EEQTew==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8iET-000LTz-2x; Tue, 05 Jul 2022 13:04:49 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8iEO-000LRk-HM for linux-arm-kernel@lists.infradead.org; Tue, 05 Jul 2022 13:04:47 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0F78760E44; Tue, 5 Jul 2022 13:04:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AE61C341C7; Tue, 5 Jul 2022 13:04:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1657026282; bh=X2byGQzH9xU1QuC680v/fmEWN9fBoq1dBxQH8XoDPIQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Kg1/TYBTib55w6uEoH1YZUkBkvUI5GCCOrEoxZ3NOkrSvnbQDgPdTIYis/G2YPTAA Y6fdQ1aF7fOA7gwZXzC1xhGc+o1QhB8HEOjHsef9eh4QmP1YP4pKlg3/loexuhaRym QuKGVGRORn0xpJh1C412G1XXTEKX4lnzWlClKL1NbXZJXKLl1lz17zG6XPS4jUiW4E zwOXV62QhW0v+84CbO7UTsu4rKJur660fz302YwStHUopedlaU0MTMZHHEhI9MJT3V zo/hOoQrDWXqKmGd3oKqtRvpk7o8Lz/n9gzVAEPL7jGAFDcF5TKbTT4/6BmPlQaum4 rqT4XxsIseVRQ== Date: Tue, 5 Jul 2022 18:34:37 +0530 From: Vinod Koul To: Samuel Holland Cc: Chen-Yu Tsai , Jernej Skrabec , Maxime Ripard , dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev Subject: Re: [PATCH] dmaengine: sun4i: Set the maximum segment size Message-ID: References: <20220621031350.36187-1-samuel@sholland.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220621031350.36187-1-samuel@sholland.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220705_060444_653062_E4A4150A X-CRM114-Status: GOOD ( 13.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 20-06-22, 22:13, Samuel Holland wrote: > The sun4i DMA engine supports transfer sizes up to 128k for normal DMA > and 16M for dedicated DMA, as documented in the A10 and A20 manuals. > > Since this is larger than the default segment size limit (64k), exposing > the real limit reduces the number of transfers needed for a transaction. > However, because the device can only report one segment size limit, we > have to expose the smaller limit from normal DMA. > > One complication is that the driver combines pairs of periodic transfers > to reduce programming overhead. This only works when the period size is > at most half of the maximum transfer size. With the default 64k segment > size limit, this was always the case, but for normal DMA it is no longer > guaranteed. Skip the optimization if the period is too long; even > without it, the overhead is less than before. Applied, thanks -- ~Vinod _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel