[PATCH] cdrom: support devices that have check_events but not media_changed

[Simon Arlott <simon@fire.lp0.eu>]

93aae17af1172c40c6f74b7294e93a90c3cfaa5d replaced the media_changed op
with the check_events op in drivers/scsi/sr.c

All users that check for the CDC_MEDIA_CHANGED capability try both
the check_events op and the media_changed op, but register_cdrom()
was requiring media_changed.

This patch fixes the capability checking and removes a redundant
check that media_changed != NULL.

The cdrom_select_disc ioctl is also using the two operations, so
they should be required for CDC_SELECT_DISC too.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
---
 drivers/cdrom/cdrom.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 14033a3..4716d76 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -409,7 +409,9 @@ int register_cdrom(struct cdrom_device_info *cdi)
 	}
 
 	ENSURE(drive_status, CDC_DRIVE_STATUS );
-	ENSURE(media_changed, CDC_MEDIA_CHANGED);
+	if (cdo->check_events == NULL && cdo->media_changed == NULL) {
+		*change_capability = ~(CDC_MEDIA_CHANGED | CDC_SELECT_DISC);
+	}
 	ENSURE(tray_move, CDC_CLOSE_TRAY | CDC_OPEN_TRAY);
 	ENSURE(lock_door, CDC_LOCK);
 	ENSURE(select_speed, CDC_SELECT_SPEED);
@@ -1471,7 +1473,7 @@ int cdrom_media_changed(struct cdrom_device_info *cdi)
 	/* This talks to the VFS, which doesn't like errors - just 1 or 0.  
 	 * Returning "0" is always safe (media hasn't been changed). Do that 
 	 * if the low-level cdrom driver dosn't support media changed. */ 
-	if (cdi == NULL || cdi->ops->media_changed == NULL)
+	if (cdi == NULL)
 		return 0;
 	if (!CDROM_CAN(CDC_MEDIA_CHANGED))
 		return 0;
-- 
1.7.0.4

-- 
Simon Arlott