Re: [PATCH] i2c: at91: use dma safe buffers

From: Michael Walle
Date: Tue Apr 05 2022 - 16:40:35 EST

Am 2022-04-05 11:23, schrieb Codrin.Ciubotariu@xxxxxxxxxxxxx:
On 03.03.2022 18:17, Michael Walle wrote:
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The supplied buffer might be on the stack and we get the following error
[ 3.312058] at91_i2c e0070600.i2c: rejecting DMA map of vmalloc memory

Use i2c_{get,put}_dma_safe_msg_buf() to get a DMA-able memory region if

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Michael Walle <michael@xxxxxxxx>

Reviewed-by: Codrin Ciubotariu <codrin.ciubotariu@xxxxxxxxxxxxx>


I'm not sure if or which Fixes: tag I should add to this patch. The issue
seems to be since a very long time, but nobody seem to have triggered it.
FWIW, I'm using the sff,sfp driver, which triggers this.

I think it should be:
Fixes: 60937b2cdbf9 ("i2c: at91: add dma support")

+ if (dev->use_dma) {
+ dma_buf = i2c_get_dma_safe_msg_buf(m_start, 1);

If you want, you could just dev->buf = i2c_get_dma_safe...

But where is the error handling in that case? dev->buf will
be NULL, which is eventually passed to dma_map_single().

Also, I need the dma_buf for the i2c_put_dma_safe_msg_buf()
call anyway, because dev->buf will be modified during