Hack to fix not working spindown over Firewire

[Tino Keitel <tino.keitel@gmx.de>]

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Hi folks,

I like the manage_start_stop feature of the SD driver to spin down the
hard disks (SATA and USB) during suspend. However, it didn't work with
my Firewire hard disk.

After some research I found out that I can spin down the disk with
sg_start --pc=2, and spin it up with sg_start --pc=1. I adopted this
into sd_start_stop_device() with the vendor name of the device
hardcoded (see the attached patch) and now my Firewire hard disk spins
down on suspend and spins up on resume.

Is there any chance to get this behaviour without such ugly changes to
the kernel? I had to make it conditional by checking the device as
otherwise the SATA disk reports an error.

Regards,
Tino

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diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 3cea17d..4d7dbd6 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1788,8 +1788,16 @@ static int sd_start_stop_device(struct scsi_disk *sdkp, int start)
 	struct scsi_device *sdp = sdkp->device;
 	int res;
 
-	if (start)
+	if (start) {
 		cmd[4] |= 1;	/* START */
+		if(!strncmp(sdp->vendor, "WDC WD32", 8)) {
+			cmd[4] |= (1 << 4); /* power condition */
+		}
+	} else {
+		if(!strncmp(sdp->vendor, "WDC WD32", 8)) {
+			cmd[4] |= (2 << 4); /* power condition */
+		}
+	}
 
 	if (!scsi_device_online(sdp))
 		return -ENODEV;