Return-path: Received: from bues.ch ([80.190.117.144]:56707 "EHLO bues.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751296Ab3EEN4m (ORCPT ); Sun, 5 May 2013 09:56:42 -0400 Date: Sun, 5 May 2013 15:56:19 +0200 From: Michael =?UTF-8?B?QsO8c2No?= To: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= Cc: Thommy Jakobsson , linville@tuxdriver.com, linux-wireless@vger.kernel.org, b43-dev@lists.infradead.org, piotras@gmail.com, Larry.Finger@lwfinger.net Subject: Re: [PATCH] B43: Handle DMA RX descriptor underrun Message-ID: <20130505155619.1f316a6b@milhouse> (sfid-20130505_155656_381655_041128EA) In-Reply-To: References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/z6/NQOpPMHu/kVznsO3vy0S"; protocol="application/pgp-signature" Sender: linux-wireless-owner@vger.kernel.org List-ID: --Sig_/z6/NQOpPMHu/kVznsO3vy0S Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Sun, 5 May 2013 14:44:14 +0200 Rafa=C5=82 Mi=C5=82ecki wrote: > 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. >=20 > 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? >=20 > 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? The ring looks the same if it's full or empty. We can only know that it is full when this interrupt fires, which happens as the indexes collide. --=20 Michael --Sig_/z6/NQOpPMHu/kVznsO3vy0S Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJRhmUDAAoJEPUyvh2QjYsOcRkP/jvbvHqTZrO8mnSGa8uiuNjY 33b+P/iTGhzWfSlpIyNtP9JVdyJTpgirUwK8qYnBt1kAxtzih6/Q+0BnrHCyuXwF +NrLY4DjgT+2egw4dkHj1Ig7TR8adOs0B4acmx0UJSje6juOmRnGUNQCRXNz9NkP o7crh6xpz6W3v2Oo0PEM8bV3PYfRYMRmczZ9YrzZzw8XEYGHixB3X6uUH47RpbM1 jf2yffHxOcmX23YOwVAX6jfFWke/l3h7rkswzeoQ0X/dUOZiN33RnXor9EL1W64H 3CX++pq0exR/WP61yUWAkljQiMxNVA1slk8iUxtL5FxRKTHyfe+Wse3OI4vdZnjb auxo3/arCdEDITpMkz2z9c+N/3VCS8G92zDZRfGTL3SIHxitqZBe5wTuLXCHlHh3 MeP+1ptoJ/W7LJ7dOIwwvh4NcrR0bLQWATd6qT8heXIQX+Jl2c7ddeOFhG3UgyNz 48I4ZxMsuo0FTJunQMAn0+Dyym6GOoZP6+g0h4efn3qeIOux5TW4VPOpy3t6tKYC FnXLAF+H5z+MkbAB6wHF9lduAwhDqhZQkkRK7bXG9lT3zjAAKSRehVN3ZsF9K9Vz WPpK/SM9VIQPBrQxAwDJsoxij8ZVtnx42qR2zjpDlDUcvO9xydCmB7uab9EUHLY5 3J5AGMbOVauOF7tS0xgw =l2pC -----END PGP SIGNATURE----- --Sig_/z6/NQOpPMHu/kVznsO3vy0S--