Re: [PATCH 21/25] ASoC: dmaengine: Convert to generic PCM copy ops

On Mon, Aug 14, 2023 at 01:55:19PM +0200, Takashi Iwai wrote:

This patch converts the ASoC dmaenging driver code to use the new unified PCM copy callback. It's a straightforward conversion from *_user() to *_iter() variants.

The process callback is still using the direct pointer as of now, but it'll be converted in the next patch.

Note that copy_from/to_iter() returns the copied bytes, hence the error condition is inverted from copy_from/to_user().

...

if (is_playback)

• if (copy_from_user(dma_ptr, buf, bytes))
  

• if (!copy_from_iter(dma_ptr, bytes, buf))
  

!= bytes ?

	return -EFAULT;

Can be compressed to a single conditional:

if (is_playback && copy_from_iter(dma_ptr, bytes, buf) != bytes)

...

if (!is_playback)

• if (copy_to_user(buf, dma_ptr, bytes))
  

• if (!copy_to_iter(dma_ptr, bytes, buf))
  return -EFAULT;
  

As per above.