From: Jan Beulich <jbeulich@novell.com>
Date: Wed, 17 Oct 2007 06:27:32 +0000 (-0700)
Subject: floppy: tolerate DMA channel unavailability
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=2e9c47cd4d451c57868c898672802eec9867ae1e;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

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 80483aac4cc..72803a3585f 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -4388,11 +4388,15 @@ 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++) {