Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760293Ab2EDVSy (ORCPT ); Fri, 4 May 2012 17:18:54 -0400 Received: from mail-pz0-f45.google.com ([209.85.210.45]:45099 "EHLO mail-pz0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759819Ab2EDUoh (ORCPT ); Fri, 4 May 2012 16:44:37 -0400 Message-Id: <20120504204225.661768143@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Fri, 04 May 2012 13:42:39 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Nicolas Ferre , Vinod Koul Subject: [ 15/75] dmaengine: at_hdmac: remove clear-on-read in atc_dostart() In-Reply-To: <20120504204258.GA12552@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1460 Lines: 43 3.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolas Ferre commit ed8b0d67f33518a16c6b2450fe5ebebf180c2d04 upstream. This loop on EBCISR register was designed to clear IRQ sources before enabling a DMA channel. This register is clear-on-read so a race condition can appear if another channel is already active and has just finished its transfer. Removing this read on EBCISR is fixing the issue as there is no case where an IRQ could be pending: we already make sure that this register is drained at probe() time and during resume. Signed-off-by: Nicolas Ferre Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- drivers/dma/at_hdmac.c | 4 ---- 1 file changed, 4 deletions(-) --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -241,10 +241,6 @@ static void atc_dostart(struct at_dma_ch vdbg_dump_regs(atchan); - /* clear any pending interrupt */ - while (dma_readl(atdma, EBCISR)) - cpu_relax(); - channel_writel(atchan, SADDR, 0); channel_writel(atchan, DADDR, 0); channel_writel(atchan, CTRLA, 0); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/