On Thu, 1 Dec 2016 19:26:04 +0800
Jisheng Zhang <jszh...@marvell.com> wrote:
> Hi Gregory, Marcin,
>
> On Wed, 30 Nov 2016 22:42:49 +0100 Gregory CLEMENT wrote:
>
> > From: Marcin Wojtas <m...@semihalf.com>
> >
> > Prepare the mvneta driver in order to be usable on the 64 bits platform
> > such as the Armada 3700.
> >
> > [gregory.clem...@free-electrons.com]: this patch was extract from a larger
> > one to ease review and maintenance.
> >
> > Signed-off-by: Marcin Wojtas <m...@semihalf.com>
> > Signed-off-by: Gregory CLEMENT <gregory.clem...@free-electrons.com>
> > ---
> > drivers/net/ethernet/marvell/mvneta.c | 17 ++++++++++++++++-
> > 1 file changed, 16 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/marvell/mvneta.c
> > b/drivers/net/ethernet/marvell/mvneta.c
> > index 92b9af14c352..8ef03fb69bcd 100644
> > --- a/drivers/net/ethernet/marvell/mvneta.c
> > +++ b/drivers/net/ethernet/marvell/mvneta.c
> > @@ -296,6 +296,12 @@
> > /* descriptor aligned size */
> > #define MVNETA_DESC_ALIGNED_SIZE 32
> >
> > +/* Number of bytes to be taken into account by HW when putting incoming
> > data
> > + * to the buffers. It is needed in case NET_SKB_PAD exceeds maximum packet
> > + * offset supported in MVNETA_RXQ_CONFIG_REG(q) registers.
>
> We also brought up this driver on 64bit platforms, we doesn't have this
> patch. Maybe I'm wrong, I'm trying to understand why we need this
> modification. Let's assume the NET_SKB_PAD is 64B, we call
> mvneta_rxq_offset_set(pp, rxq, 64),
>
> {
> u32 val;
>
> val = mvreg_read(pp, MVNETA_RXQ_CONFIG_REG(rxq->id));
> val &= ~MVNETA_RXQ_PKT_OFFSET_ALL_MASK;
>
> /* Offset is in */
> val |= MVNETA_RXQ_PKT_OFFSET_MASK(offset >> 3);
> // then this will be "val |= 8;" it doesn't exceeds the max offset of
sorry, this will be "val |= MVNETA_RXQ_PKT_OFFSET_MASK(8);"
> MVNETA_RXQ_CONFIG_REG(q) register.
>
> Could you please kindly point out where I am wrong?
>
> > + */
> > +#define MVNETA_RX_PKT_OFFSET_CORRECTION 64
> > +
> > #define MVNETA_RX_PKT_SIZE(mtu) \
> > ALIGN((mtu) + MVNETA_MH_SIZE + MVNETA_VLAN_TAG_LEN + \
> > ETH_HLEN + ETH_FCS_LEN, \
> > @@ -416,6 +422,7 @@ struct mvneta_port {
> > u64 ethtool_stats[ARRAY_SIZE(mvneta_statistics)];
> >
> > u32 indir[MVNETA_RSS_LU_TABLE_SIZE];
> > + u16 rx_offset_correction;
> > };
> >
> > /* The mvneta_tx_desc and mvneta_rx_desc structures describe the
> > @@ -1807,6 +1814,7 @@ static int mvneta_rx_refill(struct mvneta_port *pp,
> > return -ENOMEM;
> > }
> >
> > + phys_addr += pp->rx_offset_correction;
> > mvneta_rx_desc_fill(rx_desc, phys_addr, data, rxq);
> > return 0;
> > }
> > @@ -2782,7 +2790,7 @@ static int mvneta_rxq_init(struct mvneta_port *pp,
> > mvreg_write(pp, MVNETA_RXQ_SIZE_REG(rxq->id), rxq->size);
> >
> > /* Set Offset */
> > - mvneta_rxq_offset_set(pp, rxq, NET_SKB_PAD);
> > + 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);
> > @@ -4033,6 +4041,13 @@ static int mvneta_probe(struct platform_device *pdev)
> >
> > pp->rxq_def = rxq_def;
> >
> > + /* 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.
>
> Even we need this patch, I'm not sure this last comment is correct or not.
> NET_SKB_PAD is defined as:
>
> #define NET_SKB_PAD max(32, L1_CACHE_BYTES)
>
> we have 64B cacheline 32bit platforms, on this platforms, the NET_SKB_PAD
> should be 64B as well.
>
> Thanks,
> Jisheng
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-ker...@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
