Return-path: Received: from mail-oa0-f45.google.com ([209.85.219.45]:50540 "EHLO mail-oa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751225Ab3EEMoQ convert rfc822-to-8bit (ORCPT ); Sun, 5 May 2013 08:44:16 -0400 Received: by mail-oa0-f45.google.com with SMTP id o17so2761493oag.4 for ; Sun, 05 May 2013 05:44:15 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: Date: Sun, 5 May 2013 14:44:14 +0200 Message-ID: (sfid-20130505_144430_841385_78EBBC0C) Subject: Re: [PATCH] B43: Handle DMA RX descriptor underrun From: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= To: Thommy Jakobsson Cc: linville@tuxdriver.com, linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org, m@bues.ch, piotras@gmail.com, Larry.Finger@lwfinger.net Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2013/4/23 Thommy Jakobsson : > Add handling of rx descriptor underflow. This fixes a fault that could > happen on slow machines, where data is received faster than the CPU can > handle. In such a case the device will use up all rx descriptors and > refuse to send any more data before confirming that it is ok. This > patch enables necessary interrupt to discover such a situation and will > handle them by dropping everything in the ring buffer. Thommy: does it mean firmware actually ignores what we write to the B43_DMA64_RXINDEX (recently renamed to the B43_DMA64_RXSTOPINDEX)? Is our set_current_rxslot and op64_set_current_rxslot (same for 32bit version) useless in this situation? Could this be a off-by-one issue? Maybe we're writing a value too low by a one and firmware believes the whole ring is empty while it's full? I think we may want turning this interrupt anyway, but I wonder if there is another issue we just hide a bit better. -- Rafał