From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mtiwmhc12.worldnet.att.net ([204.127.131.116]:47923 "EHLO mtiwmhc12.worldnet.att.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751500AbYGBQzA (ORCPT ); Wed, 2 Jul 2008 12:55:00 -0400 Message-ID: <486BB332.6000703@lwfinger.net> (sfid-20080702_185505_871837_D7351577) Date: Wed, 02 Jul 2008 11:56:18 -0500 From: Larry Finger MIME-Version: 1.0 To: akpm@linux-foundation.org CC: Adrian Bunk , dhowells@redhat.com, linville@tuxdriver.com, mb@bu3sch.de, stefano.brivio@polimi.it, Broadcom Linux , wireless Subject: Re: + drivers-net-wireless-b43legacy-dmac-remove-the-switch-in-b43legacy_dma_init.patch added to -mm tree References: <200807020835.m628Zx2e007473@imap1.linux-foundation.org> In-Reply-To: <200807020835.m628Zx2e007473@imap1.linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: akpm@linux-foundation.org wrote: > The patch titled > drivers/net/wireless/b43legacy/dma.c: remove the switch in b43legacy_dma_init() > has been added to the -mm tree. Its filename is > drivers-net-wireless-b43legacy-dmac-remove-the-switch-in-b43legacy_dma_init.patch > > ------------------------------------------------------ > Subject: drivers/net/wireless/b43legacy/dma.c: remove the switch in b43legacy_dma_init() > From: Adrian Bunk > > The gcc 3.4 fork used to compile the MN10300 port emits unwanted > __ucmpdi2() calls for this switch on a 64bit value. > > Fix it by transforming the switch to equivalent "if ... else if ..." > statements. > > Signed-off-by: Adrian Bunk > Cc: David Howells > Cc: Stefano Brivio > Cc: John W. Linville > Cc: Michael Buesch > Cc: Larry Finger > Signed-off-by: Andrew Morton > --- > > drivers/net/wireless/b43legacy/dma.c | 16 ++++++---------- > 1 file changed, 6 insertions(+), 10 deletions(-) > > diff -puN drivers/net/wireless/b43legacy/dma.c~drivers-net-wireless-b43legacy-dmac-remove-the-switch-in-b43legacy_dma_init drivers/net/wireless/b43legacy/dma.c > --- a/drivers/net/wireless/b43legacy/dma.c~drivers-net-wireless-b43legacy-dmac-remove-the-switch-in-b43legacy_dma_init > +++ a/drivers/net/wireless/b43legacy/dma.c > @@ -1027,19 +1027,15 @@ int b43legacy_dma_init(struct b43legacy_ > enum b43legacy_dmatype type; > > dmamask = supported_dma_mask(dev); > - switch (dmamask) { > - default: > - B43legacy_WARN_ON(1); > - case DMA_30BIT_MASK: > + > + if (dmamask == DMA_30BIT_MASK) > type = B43legacy_DMA_30BIT; > - break; > - case DMA_32BIT_MASK: > + else if (dmamask == DMA_32BIT_MASK) > type = B43legacy_DMA_32BIT; > - break; > - case DMA_64BIT_MASK: > + else if (dmamask == DMA_64BIT_MASK) > type = B43legacy_DMA_64BIT; > - break; > - } > + else > + B43legacy_WARN_ON(1); > > err = ssb_dma_set_mask(dev->dev, dmamask); > if (err) { > _ Andrew, When I received your E-mail, I wondered why there was not a similar "fix" for b43. It was then I discovered how much b43 and b43legacy had diverged while I wasn't looking. I have no objections to your patch; however, I wonder if it might be better to fix b43legacy in the same way that b43 was changed. I have prepared and tested such a fix (shown below). The only problem with this is that the patch is much more intrusive than Adrian's and there may be a problem getting it into 2.6.26 before it is released, but then I do not think that you intend to send the -mm patch to 2.6.26. What do you think is the best route to go? Larry ================================================= Index: linux-2.6/drivers/net/wireless/b43legacy/dma.c =================================================================== --- linux-2.6.orig/drivers/net/wireless/b43legacy/dma.c +++ linux-2.6/drivers/net/wireless/b43legacy/dma.c @@ -860,6 +860,18 @@ static u64 supported_dma_mask(struct b43 return DMA_30BIT_MASK; } +static enum b43legacy_dmatype dma_mask_to_engine_type(u64 dmamask) +{ + if (dmamask == DMA_30BIT_MASK) + return B43legacy_DMA_30BIT; + if (dmamask == DMA_32BIT_MASK) + return B43legacy_DMA_32BIT; + if (dmamask == DMA_64BIT_MASK) + return B43legacy_DMA_64BIT; + B43legacy_WARN_ON(1); + return B43legacy_DMA_30BIT; +} + /* Main initialization function. */ static struct b43legacy_dmaring *b43legacy_setup_dmaring(struct b43legacy_wldev *dev, @@ -1019,6 +1031,43 @@ void b43legacy_dma_free(struct b43legacy dma->tx_ring0 = NULL; } +static int b43legacy_dma_set_mask(struct b43legacy_wldev *dev, u64 mask) +{ + u64 orig_mask = mask; + bool fallback = 0; + int err; + + /* Try to set the DMA mask. If it fails, try falling back to a + * lower mask, as we can always also support a lower one. */ + while (1) { + err = ssb_dma_set_mask(dev->dev, mask); + if (!err) + break; + if (mask == DMA_64BIT_MASK) { + mask = DMA_32BIT_MASK; + fallback = 1; + continue; + } + if (mask == DMA_32BIT_MASK) { + mask = DMA_30BIT_MASK; + fallback = 1; + continue; + } + b43legacyerr(dev->wl, "The machine/kernel does not support " + "the required %u-bit DMA mask\n", + (unsigned int)dma_mask_to_engine_type(orig_mask)); + return -EOPNOTSUPP; + } + if (fallback) { + b43legacyinfo(dev->wl, "DMA mask fallback from %u-bit to %u-" + "bit\n", + (unsigned int)dma_mask_to_engine_type(orig_mask), + (unsigned int)dma_mask_to_engine_type(mask)); + } + + return 0; +} + int b43legacy_dma_init(struct b43legacy_wldev *dev) { struct b43legacy_dma *dma = &dev->dma; @@ -1028,21 +1077,8 @@ int b43legacy_dma_init(struct b43legacy_ enum b43legacy_dmatype type; dmamask = supported_dma_mask(dev); - switch (dmamask) { - default: - B43legacy_WARN_ON(1); - case DMA_30BIT_MASK: - type = B43legacy_DMA_30BIT; - break; - case DMA_32BIT_MASK: - type = B43legacy_DMA_32BIT; - break; - case DMA_64BIT_MASK: - type = B43legacy_DMA_64BIT; - break; - } - - err = ssb_dma_set_mask(dev->dev, dmamask); + type = dma_mask_to_engine_type(dmamask); + err = b43legacy_dma_set_mask(dev, dmamask); if (err) { #ifdef CONFIG_B43LEGACY_PIO b43legacywarn(dev->wl, "DMA for this device not supported. 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