ohci1394: make phys_dma parameter read-only

Being able to switch physical DMA on and off at run time would be a nice
feature but a PITA to support by highlevel drivers and userspace apps.
Therefore allow it only to be set when the driver is being loaded.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>

drivers/ieee1394/ohci1394.c

@@ -163,7 +163,7 @@ printk(level "%s: fw-host%d: " fmt "\n" , OHCI1394_DRIVER_NAME, ohci->host->id ,
 
 /* Module Parameters */
 static int phys_dma = 1;
-module_param(phys_dma, int, 0644);
+module_param(phys_dma, int, 0444);
 MODULE_PARM_DESC(phys_dma, "Enable physical dma (default = 1).");
 
 static void dma_trm_tasklet(unsigned long data);