From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Dooks Subject: Re: [PATCH 1/2] s3c24xx: DMA: don't use autoreload feature Date: Wed, 08 Sep 2010 00:37:00 +0100 Message-ID: <4C86CC9C.9070506@fluff.org> References: <1283872143-32492-1-git-send-email-anarsoul@gmail.com> <1283901799-20461-1-git-send-email-anarsoul@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from dsl78-143-211-26.in-addr.fast.co.uk ([78.143.211.26]:55994 "EHLO ben-laptop" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1756557Ab0IGXir (ORCPT ); Tue, 7 Sep 2010 19:38:47 -0400 In-Reply-To: <1283901799-20461-1-git-send-email-anarsoul@gmail.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Vasily Khoruzhick Cc: Ben Dooks , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, Thomas Kleffel On 08/09/10 00:23, Vasily Khoruzhick wrote: > Some integrated DMA-capable hardware doesn't like autoreload > feature of s3c24xx DMA-engine, that's why s3cmci driver > didn't work with DMA transfers enabled. > > I rewrote DMA driver not to use autoreload feature and removed > all pre-loading features. Buffer re-load is fast enought to perform > it in IRQ handler, and anyway I don't see any reason to waste CPU > cycles on waiting for buffer load. Driver is much simplier now, > it was tested with s3cmci and s3c24xx-i2s drivers on s3c2442 and > s3c2410 SoCs and works just nice. I found this really necessary, especially on systems where some drivers can keep the cpu irq load high, such as pio hard-discs. Can this be changed to a flag that is set to control the behaviour on a per driver basis? From mboxrd@z Thu Jan 1 00:00:00 1970 From: ben-linux@fluff.org (Ben Dooks) Date: Wed, 08 Sep 2010 00:37:00 +0100 Subject: [PATCH 1/2] s3c24xx: DMA: don't use autoreload feature In-Reply-To: <1283901799-20461-1-git-send-email-anarsoul@gmail.com> References: <1283872143-32492-1-git-send-email-anarsoul@gmail.com> <1283901799-20461-1-git-send-email-anarsoul@gmail.com> Message-ID: <4C86CC9C.9070506@fluff.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/09/10 00:23, Vasily Khoruzhick wrote: > Some integrated DMA-capable hardware doesn't like autoreload > feature of s3c24xx DMA-engine, that's why s3cmci driver > didn't work with DMA transfers enabled. > > I rewrote DMA driver not to use autoreload feature and removed > all pre-loading features. Buffer re-load is fast enought to perform > it in IRQ handler, and anyway I don't see any reason to waste CPU > cycles on waiting for buffer load. Driver is much simplier now, > it was tested with s3cmci and s3c24xx-i2s drivers on s3c2442 and > s3c2410 SoCs and works just nice. I found this really necessary, especially on systems where some drivers can keep the cpu irq load high, such as pio hard-discs. Can this be changed to a flag that is set to control the behaviour on a per driver basis?