Currenly, f_midi_free uses snd_card_free, which will wait
until the user has released the sound card before
returning. However, if the user doesn't release the sound
card, then f_midi_free can block for an arbitrary amount
of time, which also blocks any gadget operations on that
thread.

Instead, we can use snd_card_free_when_closed which returns
before all handles are released. Since f_midi can be
accessed through rmidi if usb_put_function is called before
release_card_device, add refcounting to f_midi_free and
have rawmidi's private free call it. The f_midi memory
is only kfreed when usb_put_function and release_card_device
have both been called.

Signed-off-by: Jerry Zhang <zhangjerry@google.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Add super speed descriptors for f_midi.

Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

These snd_rawmidi_ops structures are only passed as the third
argument of snd_rawmidi_set_ops.  This argument is const, so the
snd_rawmidi_ops structures can be const too.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

The default_length parameter of alloc_ep_req was not really necessary
and gadget drivers would almost always create an inline function to pass
the same value to len and default_len.

This patch removes that parameter and updates all calls to alloc_ep_req() to
use the new API.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

This change makes sure that the ALSA buffers are cleaned if an endpoint
becomes disabled.

Before this change, if the internal ALSA buffer did overflow, the MIDI
function would stop sending MIDI to the host.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

This refactor results in a cleaner state machine code and promotes
consistency, readability, and maintanability of this driver.

This refactor state machine was well tested and it is currently running in
production code and devices.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

512 is the value used by wMaxPacketSize, as specified by the USB Spec. This
makes sure this driver uses, by default, the most optimal value for IN and OUT
endpoint requests.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

The new version of alloc_ep_req() already aligns the buffer size to
wMaxPacketSize on OUT endpoints.

Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

We added some new locking here, but missed an error path where we need
to unlock.

Fixes: 9acdf4df2fc4 ('usb: gadget: f_midi: added spinlock on transmit function')
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

buflen by default (256) is smaller than wMaxPacketSize (512) in high-speed
devices.

That caused the OUT endpoint to freeze if the host send any data packet of
length greater than 256 bytes.

This is an example dump of what happended on that enpoint:
HOST:   [DATA][Length=260][...]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
HOST:   [PING]
DEVICE: [NAK]
...
HOST:   [PING]
DEVICE: [NAK]

This patch fixes this problem by setting the minimum usb_request's buffer size
for the OUT endpoint as its wMaxPacketSize.

Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Felipe F. Tonello <eu@felipetonello.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>