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Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address

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Hi Gregory,

Another remark below, sorry for noise.

2016-11-29 10:37 GMT+01:00 Gregory CLEMENT <gregory.clement@free-electrons.com>:
> Until now the virtual address of the received buffer were stored in the
> cookie field of the rx descriptor. However, this field is 32-bits only
> which prevents to use the driver on a 64-bits architecture.
>
> With this patch the virtual address is stored in an array not shared with
> the hardware (no more need to use the DMA API). Thanks to this, it is
> possible to use cache contrary to the access of the rx descriptor member.
>
> The change is done in the swbm path only because the hwbm uses the cookie
> field, this also means that currently the hwbm is not usable in 64-bits.
>
> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> ---
>  drivers/net/ethernet/marvell/mvneta.c | 93 ++++++++++++++++++++++++----
>  1 file changed, 81 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> index 1b84f746d748..32b142d0e44e 100644
> --- a/drivers/net/ethernet/marvell/mvneta.c
> +++ b/drivers/net/ethernet/marvell/mvneta.c
> @@ -561,6 +561,9 @@ struct mvneta_rx_queue {
>         u32 pkts_coal;
>         u32 time_coal;
>
> +       /* Virtual address of the RX buffer */
> +       void  **buf_virt_addr;
> +
>         /* Virtual address of the RX DMA descriptors array */
>         struct mvneta_rx_desc *descs;
>
> @@ -1573,10 +1576,14 @@ static void mvneta_tx_done_pkts_coal_set(struct mvneta_port *pp,
>
>  /* Handle rx descriptor fill by setting buf_cookie and buf_phys_addr */
>  static void mvneta_rx_desc_fill(struct mvneta_rx_desc *rx_desc,
> -                               u32 phys_addr, u32 cookie)
> +                               u32 phys_addr, void *virt_addr,
> +                               struct mvneta_rx_queue *rxq)
>  {
> -       rx_desc->buf_cookie = cookie;
> +       int i;
> +
>         rx_desc->buf_phys_addr = phys_addr;
> +       i = rx_desc - rxq->descs;
> +       rxq->buf_virt_addr[i] = virt_addr;
>  }
>
>  /* Decrement sent descriptors counter */
> @@ -1781,7 +1788,8 @@ EXPORT_SYMBOL_GPL(mvneta_frag_free);
>
>  /* Refill processing for SW buffer management */
>  static int mvneta_rx_refill(struct mvneta_port *pp,
> -                           struct mvneta_rx_desc *rx_desc)
> +                           struct mvneta_rx_desc *rx_desc,
> +                           struct mvneta_rx_queue *rxq)
>
>  {
>         dma_addr_t phys_addr;
> @@ -1799,7 +1807,7 @@ static int mvneta_rx_refill(struct mvneta_port *pp,
>                 return -ENOMEM;
>         }
>
> -       mvneta_rx_desc_fill(rx_desc, phys_addr, (u32)data);
> +       mvneta_rx_desc_fill(rx_desc, phys_addr, data, rxq);
>         return 0;
>  }
>
> @@ -1861,7 +1869,12 @@ static void mvneta_rxq_drop_pkts(struct mvneta_port *pp,
>
>         for (i = 0; i < rxq->size; i++) {
>                 struct mvneta_rx_desc *rx_desc = rxq->descs + i;
> -               void *data = (void *)rx_desc->buf_cookie;
> +               void *data;
> +
> +               if (!pp->bm_priv)
> +                       data = rxq->buf_virt_addr[i];
> +               else
> +                       data = (void *)(uintptr_t)rx_desc->buf_cookie;

Dropping packets for HWBM (in fact returning dropped buffers to the
pool) is done a couple of lines above. This point will never be
reached with HWBM enabled (and it's also incorrect).

Best regards,
Marcin

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[PATCH v3 net-next 0/6] Support Armada 37xx SoC (ARMv8 64-bits) in mvneta driver Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:40 +0100
  [PATCH v3 net-next 4/6] net: mvneta: Only disable mvneta_bm for 64-bits Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:50 +0100
  [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:50 +0100
    Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to  store the rx buffer virtual address Marcin Wojtas <mw@semihalf.com> - 2016-11-29 11:00 +0100
      Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 11:30 +0100
        Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to  store the rx buffer virtual address Marcin Wojtas <mw@semihalf.com> - 2016-11-29 11:40 +0100
          Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 11:40 +0100
    Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to  store the rx buffer virtual address Marcin Wojtas <mw@semihalf.com> - 2016-11-29 11:00 +0100
      Re: [PATCH v3 net-next 2/6] net: mvneta: Use cacheable memory to store the rx buffer virtual address Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 11:20 +0100
  [PATCH v3 net-next 3/6] net: mvneta: Convert to be 64 bits compatible Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:50 +0100
  [PATCH v3 net-next 5/6] net: mvneta: Add network support for Armada 3700 SoC Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:50 +0100
  [PATCH v3 net-next 1/6] net: mvneta: Optimize rx path for small frame Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 10:50 +0100
  Re: [PATCH v3 net-next 0/6] Support Armada 37xx SoC (ARMv8 64-bits) in mvneta driver Gregory CLEMENT <gregory.clement@free-electrons.com> - 2016-11-29 11:10 +0100

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