On Mon, Jun 03, 2019 at 03:57:00PM -0600, Robert Hancock wrote:
> This driver was casting skb pointers to u32 and storing them as such in
> the DMA buffer descriptor, which is obviously broken on 64-bit. The area
> of the buffer descriptor being used is not accessed by the hardware and
> has sufficient room for a 32 or 64-bit pointer, so just store the skb
> pointer as such.
>
> Signed-off-by: Robert Hancock <hanc...@sedsystems.ca>
> ---
> drivers/net/ethernet/xilinx/xilinx_axienet.h | 11 +++-------
> drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 26
> ++++++++++++-----------
> 2 files changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet.h
> b/drivers/net/ethernet/xilinx/xilinx_axienet.h
> index 011adae..e09dc14 100644
> --- a/drivers/net/ethernet/xilinx/xilinx_axienet.h
> +++ b/drivers/net/ethernet/xilinx/xilinx_axienet.h
> @@ -356,9 +356,6 @@
> * @app2: MM2S/S2MM User Application Field 2.
> * @app3: MM2S/S2MM User Application Field 3.
> * @app4: MM2S/S2MM User Application Field 4.
> - * @sw_id_offset: MM2S/S2MM Sw ID
> - * @reserved5: Reserved and not used
> - * @reserved6: Reserved and not used
> */
> struct axidma_bd {
> u32 next; /* Physical address of next buffer descriptor */
> @@ -373,11 +370,9 @@ struct axidma_bd {
> u32 app1; /* TX start << 16 | insert */
> u32 app2; /* TX csum seed */
> u32 app3;
> - u32 app4;
> - u32 sw_id_offset;
> - u32 reserved5;
> - u32 reserved6;
> -};
> + u32 app4; /* Last field used by HW */
> + struct sk_buff *skb;
> +} __aligned(XAXIDMA_BD_MINIMUM_ALIGNMENT);
Hi Robert
Is the memory for the descriptor non-cachable? I expect so. You may
get slightly better performance if you were to keep an shadow array in
normal RAM. But this is O.K. as well.
Reviewed-by: Andrew Lunn <and...@lunn.ch>
Andrew
