Return-path: Received: from nbd.name ([88.198.39.176]:50235 "EHLO ds10.nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754065Ab0ENO2f (ORCPT ); Fri, 14 May 2010 10:28:35 -0400 Message-ID: <4BED5E08.3050000@openwrt.org> Date: Fri, 14 May 2010 16:28:24 +0200 From: Felix Fietkau MIME-Version: 1.0 To: tom.leiming@gmail.com CC: lrodriguez@atheros.com, linux-wireless@vger.kernel.org, linville@tuxdriver.com Subject: Re: [PATCH 2/2] ath9k: fix dma sync in rx path References: <1273842938-3401-1-git-send-email-tom.leiming@gmail.com> <1273842969-3435-1-git-send-email-tom.leiming@gmail.com> In-Reply-To: <1273842969-3435-1-git-send-email-tom.leiming@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2010-05-14 3:16 PM, tom.leiming@gmail.com wrote: > From: Ming Lei > > If buffer is to be accessed by cpu after dma transfer is over, but > between dma mapping and dma unmapping, we should use > dma_sync_single_for_cpu to sync the buffer between cpu with > device. And dma_sync_single_for_device is used to let > device gain the buffer again. I think this patch is wrong. On most MIPS devices, dma_sync_single_for_cpu is a no-op. In fact, with this patch, the rx path fails very quickly. I believe keeping the dma_sync_single_for_device variant is necessary for all syncs. - Felix