From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH RFC 24/30] net: fec: better implementation of iMX6 ERR006358 quirk Date: Sun, 22 Jun 2014 09:49:11 +0100 Message-ID: <20140622084911.GD32514@n2100.arm.linux.org.uk> References: <20140620121118.GR32514@n2100.arm.linux.org.uk> <316b383d2512440db51ea7c55992920d@BLUPR03MB373.namprd03.prod.outlook.com> <20140622081234.GB32514@n2100.arm.linux.org.uk> <56f5e44adf0b41a0bbf52c38b755afbd@BLUPR03MB373.namprd03.prod.outlook.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-arm-kernel@lists.infradead.org" , "netdev@vger.kernel.org" To: "fugang.duan@freescale.com" Return-path: Received: from gw-1.arm.linux.org.uk ([78.32.30.217]:38165 "EHLO pandora.arm.linux.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750998AbaFVItQ (ORCPT ); Sun, 22 Jun 2014 04:49:16 -0400 Content-Disposition: inline In-Reply-To: <56f5e44adf0b41a0bbf52c38b755afbd@BLUPR03MB373.namprd03.prod.outlook.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sun, Jun 22, 2014 at 08:38:49AM +0000, fugang.duan@freescale.com wrote: > From: Russell King - ARM Linux Data: Sunday, June 22, 2014 4:13 PM > >To: Duan Fugang-B38611 > >Cc: linux-arm-kernel@lists.infradead.org; netdev@vger.kernel.org > >Subject: Re: [PATCH RFC 24/30] net: fec: better implementation of iMX6 > >ERR006358 quirk > > > >On Sun, Jun 22, 2014 at 07:49:11AM +0000, fugang.duan@freescale.com wrote: > >> From: Russell King Data: Friday, June 20, 2014 > >> 8:14 PM > >> >To: linux-arm-kernel@lists.infradead.org > >> >Cc: Duan Fugang-B38611; netdev@vger.kernel.org > >> >Subject: [PATCH RFC 24/30] net: fec: better implementation of iMX6 > >> >ERR006358 quirk > >> > > >> >+ > >> >+ /* ERR006538: Keep the transmitter going */ > >> >+ if (fep->dirty_tx != fep->cur_tx && > >> >+ readl(fep->hwp + FEC_X_DES_ACTIVE) == 0) > >> >+ writel(0, fep->hwp + FEC_X_DES_ACTIVE); > >> > } > >> > ... > >While I agree that we can read back to check whether the device indicates > >that transmit is active, there's no point to the other tests. If there > >are entries in the transmit ring but the transmitter indicates that it is > >not active, then it is obvious that the bug has been hit. This is exactly > >what my implementation above does. > > > The condition "fep->dirty_tx != fep->cur_tx" is not only limited for the errata. > I mean only add extra trigger TDAR for the issue. Yes, I agree that test is wrong (that's what comes from shuffling the patches... subsequent patches modify the indexing mechanism). It should be: if (bdp != fep->cur_tx && readl(fep->hwp + FEC_X_DES_ACTIVE) == 0) writel(0, fep->hwp + FEC_X_DES_ACTIVE); Since "bdp" is the post-incremented dirty_tx pointer, which, when it is equal to fep->cur_tx means that the ring is empty. -- FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly improving, and getting towards what was expected from it.