[PATCH] ALSA: rawmidi: introduce SNDRV_RAWMIDI_IOCTL_USER_PVERSION

[David Henningsson]

On 2021-09-20 10:35, Jaroslav Kysela wrote:
> The new framing mode causes the user space regression, because
> the alsa-lib code does not initialize the reserved space in
> the params structure when the device is opened.
>
> This change adds SNDRV_RAWMIDI_IOCTL_USER_PVERSION like we
> do for the PCM interface for the protocol acknowledgment.
>
> Cc: David Henningsson <coding at diwic.se>
> Cc: <stable at vger.kernel.org>
> Fixes: 08fdced60ca0 ("ALSA: rawmidi: Add framing mode")
> BugLink: https://github.com/alsa-project/alsa-lib/issues/178
> Signed-off-by: Jaroslav Kysela <perex at perex.cz>
> ---
>   include/sound/rawmidi.h     | 1 +
>   include/uapi/sound/asound.h | 1 +
>   sound/core/rawmidi.c        | 9 +++++++++
>   3 files changed, 11 insertions(+)
>
> diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
> index 989e1517332d..7a08ed2acd60 100644
> --- a/include/sound/rawmidi.h
> +++ b/include/sound/rawmidi.h
> @@ -98,6 +98,7 @@ struct snd_rawmidi_file {
>   	struct snd_rawmidi *rmidi;
>   	struct snd_rawmidi_substream *input;
>   	struct snd_rawmidi_substream *output;
> +	unsigned int user_pversion;	/* supported protocol version */
>   };
>   
>   struct snd_rawmidi_str {
> diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
> index 1d84ec9db93b..f906e50a7919 100644
> --- a/include/uapi/sound/asound.h
> +++ b/include/uapi/sound/asound.h
> @@ -784,6 +784,7 @@ struct snd_rawmidi_status {
>   
>   #define SNDRV_RAWMIDI_IOCTL_PVERSION	_IOR('W', 0x00, int)
>   #define SNDRV_RAWMIDI_IOCTL_INFO	_IOR('W', 0x01, struct snd_rawmidi_info)
> +#define SNDRV_RAWMIDI_IOCTL_USER_PVERSION _IOW('A', 0x02, int)

How come it's not 'W' here but 'A' instead?

Looks good otherwise, given a quick glance. It'll need a corresponding 
alsa-lib patch to actually call SNDRV_RAWMIDI_IOCTL_USER_PVERSION.

Thanks for helping to sort this out.

// David