Re: [PATCH] drivers: rtl818x: request DMA-able memory

[Johannes Berg]

On Mon, 2010-10-25 at 15:11 +0100, Hin-Tak Leung wrote:

> >> Despite the indicated intention in comment, the kmalloc() call was not
> >> explicitly requesting memory from ZONE_DMA.

> I had a quick look for similiar constructs and AFAIK only the b43/b43legacy 
> drivers uses DMA buffers. Seems to be a rare practice. Is that something we 
> should or should not do?

I think there's some confusion here about ZONE_DMA vs. DMA-able memory.
All memory you get with kmalloc can be used for DMA, GFP_DMA means using
ZONE_DMA which is a hack for ISA (and in b43 maybe PCMCIA/Cardbus)
devices to put memory into something they can address. I don't think the
latter is necessary for USB devices.

johannes

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/