[PATCH 6/6] staging: most: Documentation: add information to driver_usage file

[Dan Carpenter]

On Wed, Dec 12, 2018 at 01:15:31PM +0100, Christian Gromm wrote:
> diff --git a/drivers/staging/most/Documentation/driver_usage.txt b/drivers/staging/most/Documentation/driver_usage.txt
> index bb9b4e8..da7a8f4 100644
> --- a/drivers/staging/most/Documentation/driver_usage.txt
> +++ b/drivers/staging/most/Documentation/driver_usage.txt
> @@ -142,8 +142,9 @@ Cdev component example:
>  
>  Sound component example:
>  
> -The sound component needs an additional parameter to determine the audio
> -resolution that is going to be used. The following formats are available:
> +The sound component needs additional parameters to determine the audio
> +resolution that is going to be used and to trigger the registration of a
> +sound card with ALSA. The following audio formats are available:
>  
>  	- "1x8" (Mono)
>  	- "2x16" (16-bit stereo)
> @@ -151,9 +152,18 @@ resolution that is going to be used. The following formats are available:
>  	- "2x32" (32-bit stereo)
>  	- "6x16" (16-bit surround 5.1)
>  
> -        $ echo "mdev0:ep_81:sound:most51_playback.6x16" >$(DRV_DIR)/add_link
> +To make the sound module create a sound card and register it with ALSA the
> +string "create" needs to be attached to the module parameter section of the
> +configuration string. To create a sound card with with two playback devices
> +(linked to channel ep01 and ep02) and one capture device (linked to channel
> +ep83) the following is written to the add_link file:
>  
> +        $ echo "mdev0:ep01:sound:most51_playback.6x16" >$(DRV_DIR)/add_link
> +        $ echo "mdev0:ep02:sound:most_playback.2x16" >$(DRV_DIR)/add_link
> +        $ echo "mdev0:ep83:sound:most_capture.2x16.create" >$(DRV_DIR)/add_link
>  
> +The link names (most51_playback, most_playback and most_capture) will
> +become the names of the PCM devices of the sound card.

So this patchset does break userspace...  Which is allowed sometimes in
staging, but it's better to point it out in the original commit which
causes the breakage.

But really I don't like this API at all...  It feels like something
from decades ago.  There has to be a better way than this.

Unfortunately, I'm not clever enough to give you useful suggestions...

regards,
dan carpenter