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    SubjectRe: [PATCH 03/12] net: ll_temac: Fix support for 64-bit platforms
    On Fri, 26 Apr 2019 09:32:22 +0200, Esben Haabendal wrote:
    > The use of buffer descriptor APP4 field (32-bit) for storing skb pointer
    > obviously does not work on 64-bit platforms.
    > As APP3 is also unused, we can use that to store the other half of 64-bit
    > pointer values.
    >
    > Contrary to what is hinted at in commit message of commit 15bfe05c8d63
    > ("net: ethernet: xilinx: Mark XILINX_LL_TEMAC broken on 64-bit")
    > there are no other pointers stored in cdmac_bd.
    >
    > Signed-off-by: Esben Haabendal <esben@geanix.com>

    This is a bit strange, the driver stores the host's virtual address into
    the HW descriptor?

    > diff --git a/drivers/net/ethernet/xilinx/Kconfig b/drivers/net/ethernet/xilinx/Kconfig
    > index da4ec57..6d68c8a 100644
    > --- a/drivers/net/ethernet/xilinx/Kconfig
    > +++ b/drivers/net/ethernet/xilinx/Kconfig
    > @@ -34,7 +34,6 @@ config XILINX_AXI_EMAC
    > config XILINX_LL_TEMAC
    > tristate "Xilinx LL TEMAC (LocalLink Tri-mode Ethernet MAC) driver"
    > depends on (PPC || MICROBLAZE)
    > - depends on !64BIT || BROKEN
    > select PHYLIB
    > ---help---
    > This driver supports the Xilinx 10/100/1000 LocalLink TEMAC
    > diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
    > index 4594fe3..a365bfd 100644
    > --- a/drivers/net/ethernet/xilinx/ll_temac_main.c
    > +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
    > @@ -619,11 +619,39 @@ static void temac_adjust_link(struct net_device *ndev)
    > mutex_unlock(&lp->indirect_mutex);
    > }
    >
    > +#ifdef CONFIG_64BIT
    > +
    > +void ptr_to_txbd(void *p, struct cdmac_bd *bd)
    > +{
    > + bd->app3 = (u32)(((u64)p) >> 32);
    > + bd->app4 = (u32)((u64)p & 0xFFFFFFFF);
    > +}
    > +
    > +void *ptr_from_txbd(struct cdmac_bd *bd)
    > +{
    > + return (void *)(((u64)(bd->app3) << 32) | bd->app4);
    > +}
    > +
    > +#else
    > +
    > +void ptr_to_txbd(void *p, struct cmdac_bd *bd)
    > +{
    > + bd->app4 = (u32)p;
    > +}
    > +
    > +void *ptr_from_txbd(struct cdmac_bd *bd)
    > +{
    > + return (void *)(bd->app4);
    > +}
    > +
    > +#endif
    > +
    > static void temac_start_xmit_done(struct net_device *ndev)
    > {
    > struct temac_local *lp = netdev_priv(ndev);
    > struct cdmac_bd *cur_p;
    > unsigned int stat = 0;
    > + struct sk_buff *skb;
    >
    > cur_p = &lp->tx_bd_v[lp->tx_bd_ci];
    > stat = cur_p->app0;
    > @@ -631,8 +659,9 @@ static void temac_start_xmit_done(struct net_device *ndev)
    > while (stat & STS_CTRL_APP0_CMPLT) {
    > dma_unmap_single(ndev->dev.parent, cur_p->phys, cur_p->len,
    > DMA_TO_DEVICE);
    > - if (cur_p->app4)
    > - dev_consume_skb_irq((struct sk_buff *)cur_p->app4);
    > + skb = (struct sk_buff *)ptr_from_txbd(cur_p);
    > + if (skb)
    > + dev_consume_skb_irq(skb);
    > cur_p->app0 = 0;
    > cur_p->app1 = 0;
    > cur_p->app2 = 0;
    > @@ -711,7 +740,7 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
    > cur_p->len = skb_headlen(skb);
    > cur_p->phys = dma_map_single(ndev->dev.parent, skb->data,
    > skb_headlen(skb), DMA_TO_DEVICE);
    > - cur_p->app4 = (unsigned long)skb;
    > + ptr_to_txbd((void *)skb, cur_p);
    >
    > for (ii = 0; ii < num_frag; ii++) {
    > lp->tx_bd_tail++;

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