Hi,
Patra, Nilkesh a écrit :
> On the latest version of MUSB, DMA is not working properly if the Data in the
> packet doesn't start at 32bit aligned address. This issue was found while
> using MUSB as g_ether. The basic ping does not work, if the data in the
> Ethernet packet does not start at 32bit aligned address.
>
> To overcome this issue, we found one solution mentioned in the below patch.
> This patch moves data (skb->data) by 2 bytes backwards in ethernet packet,
> which is nothing but skb->head.
>
> I want to know, if there are any better approaches to fix this issue.
>
What dma_mask are you using ?
>From what I understand, dma_map_single will use it to know if the dma
buffer need to be aligned [1].
So you need to set the last 2 bits to 0 and it should do everything for you.
Matthieu
[1]
/*
* Figure out if we need to bounce from the DMA mask.
*/
needs_bounce = (dma_addr | (dma_addr + size - 1)) & ~mask;
}
if (device_info && (needs_bounce || dma_needs_bounce(dev, dma_addr,
size))) {
struct safe_buffer *buf;
buf = alloc_safe_buffer(device_info, ptr, size, dir);
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