From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Steffen Trumtrar <s.trumtrar@pengutronix.de>,
barebox@lists.infradead.org
Subject: Re: [PATCH 1/2] net: macb: fix dma_alloc for rx_buffer
Date: Wed, 29 Nov 2023 07:25:10 +0100 [thread overview]
Message-ID: <8b33b974-e280-4f60-911d-c26ed4d69668@pengutronix.de> (raw)
In-Reply-To: <20231128-v2023-08-0-topic-macb-v1-1-9faff73bc990@pengutronix.de>
Hello Steffen,
On 28.11.23 17:29, Steffen Trumtrar wrote:
> rx_buffer gets dma_alloc'ed but is never dma_map'ed and therefor not
> flushed before it is initially used.
>
> Map the rx_buffer when the macb is initialized and unmap it on ether_halt.
>
> While at it, cleanup the dma_alloc_coherent rx_ring/tx_ring, too.
>
> Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
> ---
> drivers/net/macb.c | 37 ++++++++++++++++++++++++++++---------
> 1 file changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/macb.c b/drivers/net/macb.c
> index 260c1e806a..92f78f7253 100644
> --- a/drivers/net/macb.c
> +++ b/drivers/net/macb.c
> @@ -63,10 +63,13 @@ struct macb_device {
> unsigned int tx_head;
>
> void *rx_buffer;
> + dma_addr_t rx_buffer_phys;
> void *tx_buffer;
> void *rx_packet_buf;
> struct macb_dma_desc *rx_ring;
> + dma_addr_t rx_ring_phys;
> struct macb_dma_desc *tx_ring;
> + dma_addr_t tx_ring_phys;
> struct macb_dma_desc *gem_q1_descs;
>
> int rx_buffer_size;
> @@ -181,7 +184,7 @@ static int gem_recv(struct eth_device *edev)
> barrier();
> status = macb->rx_ring[macb->rx_tail].ctrl;
> length = MACB_BFEXT(RX_FRMLEN, status);
> - buffer = macb->rx_buffer + macb->rx_buffer_size * macb->rx_tail;
> + buffer = (void *)macb->rx_buffer_phys + macb->rx_buffer_size * macb->rx_tail;
For GEM-type NICs, rx_buffer_size is PKTSIZE (1518 bytes currently), which is not a multiple
of the cache line size of the 64 bytes cache line on the ZynqMP's Cortex-A53 the driver
is supposed to support.
> dma_sync_single_for_cpu(macb->dev, (unsigned long)buffer, length,
> DMA_FROM_DEVICE);
This means this could potentially invalidate adjacent buffer contents.
> }
> @@ -891,8 +908,8 @@ static int macb_probe(struct device *dev)
>
> macb_init_rx_buffer_size(macb, PKTSIZE);
^ Here's where PKTSIZE comes from. I'd be in favor of changing the global PKTSIZE
definition to be a multiple of 64 bytes (or use DMA_ALIGNMENT, but this isn't
correctly set for ARM yet. I just sent out a patch for that).
Cheers,
Ahmad
--
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next prev parent reply other threads:[~2023-11-29 6:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-28 16:29 [PATCH 0/2] net: macb: fix dma usage Steffen Trumtrar
2023-11-28 16:29 ` [PATCH 1/2] net: macb: fix dma_alloc for rx_buffer Steffen Trumtrar
2023-11-28 16:56 ` Lucas Stach
2023-11-29 6:48 ` Steffen Trumtrar
2023-11-29 6:25 ` Ahmad Fatoum [this message]
2023-11-28 16:29 ` [PATCH 2/2] net: macb: convert to volatile accesses Steffen Trumtrar
2023-11-29 6:31 ` Ahmad Fatoum
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