Re: [PATCH V3 1/2] i2c: qup: Fix broken dma when CONFIG_DEBUG_SG is enabled

From: Wolfram Sang
Date: Thu May 26 2016 - 14:48:16 EST

> sg_set_buf expects that the buf parameter passed in should be from
> lowmem and a valid pageframe. This is not true for pages from
> dma_alloc_coherent which can be carveouts, hence the check fails.

OK, given you mean dma_pool_alloc here, the check fails for the
pageframe because of the pool? Is my understanding correct?

> Change allocation of sg buffers from dma_coherent memory to kzalloc
> to fix the issue.

But why can you drop the coherency?

> @@ -1268,6 +1260,8 @@ static int qup_i2c_xfer_v2(struct i2c_adapter *adap,
> }
> }
> + idx = 0;
> +

This looks like an unrelated change.

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