Implement a downcounter for the synchronize cache command. There are devices

that do not support it (probably because they do not have a cache at all like
in flash media) and this should at least avoid spamming the syslog when this is
the case. It will try 5 times and then disable syncing for that device. Untested
as of yet though.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24803 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/drivers/disk/usb/usb_disk/usb_disk.cpp

@@ -436,10 +436,21 @@ usb_disk_update_capacity(device_lun *lun)
 status_t
 usb_disk_synchronize(device_lun *lun, bool force)
 {
+	if (lun->device->sync_support == 0) {
+		// this device repeatedly reported an illegal request when syncing
+		// it obviously does really not support this command...
+		return B_UNSUPPORTED;
+	}
+
 	if (lun->should_sync || force) {
 		status_t result = usb_disk_operation(lun, SCSI_SYNCHRONIZE_CACHE_10,
 			10, 0, 0, NULL, NULL, false);
 		lun->should_sync = false;
+
+		if (result == B_OK)
+			lun->device->sync_support = SYNC_SUPPORT_RELOAD;
+		else if (result == B_DEV_INVALID_IOCTL)
+			lun->device->sync_support--;
 		return result;
 	}
 
@@ -474,6 +485,7 @@ usb_disk_device_added(usb_device newDevice, void **cookie)
 	device->open_count = 0;
 	device->interface = 0xff;
 	device->current_tag = 0;
+	device->sync_support = SYNC_SUPPORT_RELOAD;
 	device->luns = NULL;
 
 	// scan through the interfaces to find our bulk-only data interface

src/add-ons/kernel/drivers/disk/usb/usb_disk/usb_disk.h

@@ -25,6 +25,8 @@
 #define CSW_STATUS_COMMAND_FAILED	0x01
 #define CSW_STATUS_PHASE_ERROR		0x02
 
+#define SYNC_SUPPORT_RELOAD			5
+
 typedef struct device_lun_s device_lun;
 
 // holds common information about an attached device (pointed to by luns)
@@ -40,6 +42,7 @@ typedef struct disk_device_s {
 	usb_pipe	bulk_out;
 	uint8		interface;
 	uint32		current_tag;
+	uint8		sync_support;
 
 	// used to store callback information
 	sem_id		notify;