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SubjectRe: [EXT] [PATCH net] net: mvneta: fix the Rx desc buffer DMA unmapping
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Hi Antoine,

On jeu., sept. 20 2018, Antoine Tenart <antoine.tenart@bootlin.com> wrote:

> Hi Yelena,
>
> On Thu, Sep 20, 2018 at 10:14:56AM +0000, Yelena Krivosheev wrote:
>>
>> Please, check and fix all cases of dma_unmap_single() usage.
>> See mvneta_rxq_drop_pkts()
>> ...
>> if (!data || !(rx_desc->buf_phys_addr))
>> continue;
>> dma_unmap_single(pp->dev->dev.parent, rx_desc->buf_phys_addr,
>> MVNETA_RX_BUF_SIZE(pp->pkt_size), DMA_FROM_DEVICE);
>> __free_page(data);
>> ...
>
> I had a look at the one reported by CONFIG_DMA_API_DEBUG, and at DMA
> unmapping calls using PAGE_SIZE. As you pointed out there might be
> others parts, thanks!

Actually Jisheng had submitted a similar patch few weeks ago and as I
pointed at this time, the dma_unmap in mvneta_rxq_drop_pkts can be
called when the allocation is done in with HWBM in this case which use a
dma_map_single.

I though that in this case using dma_map_single is the things to do even
if in the SWBM case it is less optimal.

Gregory

>
> Antoine
>
> --
> Antoine Ténart, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

--
Gregory Clement, Bootlin
Embedded Linux and Kernel engineering
http://bootlin.com

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