[PATCH] i2c: mxs: ensure that DMA buffers are safe for DMA

[Wolfram Sang]

On Mon, Feb 13, 2023 at 04:25:50PM +0100, Matthias Schiffer wrote:
> We found that after commit 9c46929e7989
> ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems"), the
> PCF85063 RTC driver stopped working on i.MX28 due to regmap_bulk_read()
> reading bogus data into a stack buffer. This is caused by the i2c-mxs
> driver using DMA transfers even for messages without the I2C_M_DMA_SAFE
> flag, and the aforementioned commit enabling vmapped stacks.
> 
> As the MXS I2C controller requires DMA for reads of >4 bytes, DMA can't be
> disabled, so the issue is fixed by using i2c_get_dma_safe_msg_buf() to
> create a bounce buffer when needed.
> 
> Fixes: 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems")
> Signed-off-by: Matthias Schiffer <matthias.schiffer at ew.tq-group.com>

Applied to for-current, thanks!

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