Re: [PATCH] i2c: i2c-qcom-geni: Properly handle DMA safe buffers

From: Wolfram Sang
Date: Tue Sep 18 2018 - 18:16:52 EST



> This fixes a problem where the kernel oopses cleaning pages for a buffer
> that's mapped into the vmalloc space. The pages are returned from
> request_firmware() and passed down directly to the i2c master to write
> to the i2c touchscreen device. Mapping vmalloc buffers with
> dma_map_single() won't work reliably, causing an oops like below:

Exactly the reason why I implemented I2C_M_DMA_SAFE. Did you also notice
the helper i2c_get_dma_safe_msg_buf() which you maybe could use for
len > 32?

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