[PATCH] net/niu: remove one superfluous dma mask check

[PATCH] net/niu: remove one superfluous dma mask check

[Sebastian Andrzej Siewior]

The idea here seems to be to get a 44bit DMA mask working and if this
fails it should fallback to a 32bit DMA mask. The dma_mask variable is
assigned once to 44bit and never updated. pci_set_dma_mask() and
pci_set_consistent_dma_mask() are both implemented as functions so there
is no evil macro which might update dma_mask. Looking at the assembly, I
see a call to dma_set_mask() followed by dma_supported() and then a jump
passed the second dma_set_mask(). The only way to get to second
dma_set_mask() call is by an error code in the first one.

So I hereby remove the check since it looks superfluous. Please ignore
the path if there is black magic involved.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/ethernet/sun/niu.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/sun/niu.c b/drivers/net/ethernet/sun/niu.c
index c99b3b0..703c8cc 100644
--- a/drivers/net/ethernet/sun/niu.c
+++ b/drivers/net/ethernet/sun/niu.c
@@ -9838,7 +9838,7 @@ static int __devinit niu_pci_init_one(struct pci_dev *pdev,
 			goto err_out_release_parent;
 		}
 	}
-	if (err || dma_mask == DMA_BIT_MASK(32)) {
+	if (err) {
 		err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
 		if (err) {
 			dev_err(&pdev->dev, "No usable DMA configuration, aborting\n");
-- 
1.7.10

Re: [PATCH] net/niu: remove one superfluous dma mask check

[David Miller]

From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu,  3 May 2012 20:22:00 +0200

> The idea here seems to be to get a 44bit DMA mask working and if this
> fails it should fallback to a 32bit DMA mask. The dma_mask variable is
> assigned once to 44bit and never updated. pci_set_dma_mask() and
> pci_set_consistent_dma_mask() are both implemented as functions so there
> is no evil macro which might update dma_mask. Looking at the assembly, I
> see a call to dma_set_mask() followed by dma_supported() and then a jump
> passed the second dma_set_mask(). The only way to get to second
> dma_set_mask() call is by an error code in the first one.
> 
> So I hereby remove the check since it looks superfluous. Please ignore
> the path if there is black magic involved.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

It looks like it's been this way since day one. :-)

Applied, thanks.