From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gregory CLEMENT Subject: Re: [PATCH 1/5] net: mvneta: fix rx_offset_correction set and usage Date: Wed, 29 Aug 2018 11:05:45 +0200 Message-ID: <87efehk0eu.fsf@bootlin.com> References: <20180829162456.2bd69796@xhacker.debian> <20180829162706.24111f9c@xhacker.debian> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Cc: , "David S. Miller" , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Lunn , linux-arm-kernel@lists.infradead.org To: Jisheng Zhang Return-path: In-Reply-To: <20180829162706.24111f9c@xhacker.debian> (Jisheng Zhang's message of "Wed, 29 Aug 2018 16:27:06 +0800") Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi Jisheng, On mer., août 29 2018, Jisheng Zhang wrote: > The rx_offset_correction is RX packet offset correction for platforms, > it's not related with SW BM, instead, it's only related with the > platform's NET_SKB_PAD. > But if I undrestood well, the value of rx_offset_correction has an influence only when we use HW BM. However since d93277b9839b ("Revert "arm64: Increase the max granular size""), NET_SKB_PAD is 64 for arm64, so in the end rx_offset_correction is always 0 for recent kernels. Gregory > Fix the issue by reverting to the original behavior. > > Fixes: 562e2f467e71 ("net: mvneta: Improve the buffer allocation method for SWBM") > Signed-off-by: Jisheng Zhang > --- > drivers/net/ethernet/marvell/mvneta.c | 24 ++++++++++-------------- > 1 file changed, 10 insertions(+), 14 deletions(-) > > diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c > index bc80a678abc3..0ce94f6587a5 100644 > --- a/drivers/net/ethernet/marvell/mvneta.c > +++ b/drivers/net/ethernet/marvell/mvneta.c > @@ -2899,21 +2899,18 @@ static void mvneta_rxq_hw_init(struct mvneta_port *pp, > mvreg_write(pp, MVNETA_RXQ_BASE_ADDR_REG(rxq->id), rxq->descs_phys); > mvreg_write(pp, MVNETA_RXQ_SIZE_REG(rxq->id), rxq->size); > > + /* Set Offset */ > + mvneta_rxq_offset_set(pp, rxq, NET_SKB_PAD - pp->rx_offset_correction); > + > /* Set coalescing pkts and time */ > mvneta_rx_pkts_coal_set(pp, rxq, rxq->pkts_coal); > mvneta_rx_time_coal_set(pp, rxq, rxq->time_coal); > > if (!pp->bm_priv) { > - /* Set Offset */ > - mvneta_rxq_offset_set(pp, rxq, 0); > mvneta_rxq_buf_size_set(pp, rxq, pp->frag_size); > mvneta_rxq_bm_disable(pp, rxq); > mvneta_rxq_fill(pp, rxq, rxq->size); > } else { > - /* Set Offset */ > - mvneta_rxq_offset_set(pp, rxq, > - NET_SKB_PAD - pp->rx_offset_correction); > - > mvneta_rxq_bm_enable(pp, rxq); > /* Fill RXQ with buffers from RX pool */ > mvneta_rxq_long_pool_set(pp, rxq); > @@ -4547,7 +4544,13 @@ static int mvneta_probe(struct platform_device *pdev) > SET_NETDEV_DEV(dev, &pdev->dev); > > pp->id = global_port_id++; > - pp->rx_offset_correction = 0; /* not relevant for SW BM */ > + > + /* Set RX packet offset correction for platforms, whose > + * NET_SKB_PAD, exceeds 64B. It should be 64B for 64-bit > + * platforms and 0B for 32-bit ones. > + */ > + pp->rx_offset_correction = > + max(0, NET_SKB_PAD - MVNETA_RX_PKT_OFFSET_CORRECTION); > > /* Obtain access to BM resources if enabled and already initialized */ > bm_node = of_parse_phandle(dn, "buffer-manager", 0); > @@ -4562,13 +4565,6 @@ static int mvneta_probe(struct platform_device *pdev) > pp->bm_priv = NULL; > } > } > - /* Set RX packet offset correction for platforms, whose > - * NET_SKB_PAD, exceeds 64B. It should be 64B for 64-bit > - * platforms and 0B for 32-bit ones. > - */ > - pp->rx_offset_correction = max(0, > - NET_SKB_PAD - > - MVNETA_RX_PKT_OFFSET_CORRECTION); > } > of_node_put(bm_node); > > -- > 2.18.0 > -- Gregory Clement, Bootlin Embedded Linux and Kernel engineering http://bootlin.com