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Date: Sun, 22 Jun 2014 09:49:11 +0100 From: Russell King - ARM Linux <linux@....linux.org.uk> To: "fugang.duan@...escale.com" <fugang.duan@...escale.com> Cc: "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: Re: [PATCH RFC 24/30] net: fec: better implementation of iMX6 ERR006358 quirk On Sun, Jun 22, 2014 at 08:38:49AM +0000, fugang.duan@...escale.com wrote: > From: Russell King - ARM Linux <linux@....linux.org.uk> Data: Sunday, June 22, 2014 4:13 PM > >To: Duan Fugang-B38611 > >Cc: linux-arm-kernel@...ts.infradead.org; netdev@...r.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@...escale.com wrote: > >> From: Russell King <rmk@....linux.org.uk> Data: Friday, June 20, 2014 > >> 8:14 PM > >> >To: linux-arm-kernel@...ts.infradead.org > >> >Cc: Duan Fugang-B38611; netdev@...r.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. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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