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Date: Mon, 16 Oct 2006 10:44:30 +1000 From: Paul Mackerras <paulus@...ba.org> To: Andrew Morton <akpm@...l.org> Cc: Alan Cox <alan@...rguk.ukuu.org.uk>, David Brownell <david-b@...bell.net>, matthew@....cx, val_henson@...ux.intel.com, netdev@...r.kernel.org, linux-pci@...ey.karlin.mff.cuni.cz, linux-kernel@...r.kernel.org, gregkh@...e.de Subject: Re: [PATCH 1/2] [PCI] Check that MWI bit really did get set Andrew Morton writes: > Let me restore the words from my earlier email which you removed so that > you could say that: > > For you the driver author to make assumptions about what's happening > inside pci_set_mwi() is a layering violation. Maybe the bridge got > hot-unplugged. Maybe the attempt to set MWI caused some synchronous PCI > error. For example, take a look at the various implementations of > pci_ops.read() around the place - various of them can fail for various > reasons. Maybe aliens are firing a ray-gun at the card. I think it's fundamentally wrong for the driver to deny service completely because of a maybe. Either there was a transient error that only affected the attempt to set MWI, in which case a printk (inside pci_set_mwi!) is appropriate, and we carry on. Or there is a persistent error condition, in which case the driver will see something else fail soon enough - something that the driver actually needs to have working in order to operate - and fail at that point. For the driver to stop and refuse to go any further because of an error in pci_set_mwi has far more disadvantages than advantages. Paul. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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