From: "Jan Beulich" 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 Signed-off-by: Andrew Morton --- drivers/block/floppy.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff -puN drivers/block/floppy.c~floppy-tolerate-dma-channel-unavailability drivers/block/floppy.c --- a/drivers/block/floppy.c~floppy-tolerate-dma-channel-unavailability +++ a/drivers/block/floppy.c @@ -4392,11 +4392,15 @@ static int floppy_grab_irq_and_dma(void) 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++) { _