floppy: tolerate DMA channel unavailability
The floppy driver is already written to be able to operate in virtual DMA
mode. Thus it can easily be adjusted to tolerate failure from
fd_request_dma() as long as virtual DMA mode is not disallowed.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index 80483aa..72803a3 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4388,11 +4388,15 @@
if (fd_request_dma()) {
DPRINT("Unable to grab DMA%d for the floppy driver\n",
FLOPPY_DMA);
- fd_free_irq();
- spin_lock_irqsave(&floppy_usage_lock, flags);
- usage_count--;
- spin_unlock_irqrestore(&floppy_usage_lock, flags);
- return -1;
+ if (can_use_virtual_dma & 2)
+ use_virtual_dma = can_use_virtual_dma = 1;
+ if (!(can_use_virtual_dma & 1)) {
+ fd_free_irq();
+ spin_lock_irqsave(&floppy_usage_lock, flags);
+ usage_count--;
+ spin_unlock_irqrestore(&floppy_usage_lock, flags);
+ return -1;
+ }
}
for (fdc = 0; fdc < N_FDC; fdc++) {