Kernel 5.13.6 breaks mmap with snd-hdsp module

[Greg KH]

On Sat, Aug 07, 2021 at 12:49:07AM -0700, Jeff Woods wrote:
> Specifically, commit c4824ae7db418aee6f50f308a20b832e58e997fd triggers the problem. Reverting this change restores functionality.
> 
> The device is an RME Multiface II, using the snd-hdsp driver.
> 
> Expected behavior: Device plays sound normally
> 
> Exhibited behavior: When a program attempts to open the device, the following ALSA lib error happens:
> 
> ALSA lib pcm_direct.c:1169:(snd1_pcm_direct_initialize_slave) slave plugin does not support mmap interleaved or mmap noninterleaved access
> 
> This change hasn't affected my other computers with less esoteric hardware, so probably the problem lies with the snd-hdsp driver, but the device is unusable without reverting that commit.
> 
> I am available to test any patches for this issue.

Have you notified the developers involved in this change about this
issue?

Adding them now...

thanks,

greg k-h