On Sat, Oct 14, 2006 at 01:48:55PM -0700, Andrew Morton wrote: > On Sat, 14 Oct 2006 08:02:49 -0600 > Matthew Wilcox <[EMAIL PROTECTED]> wrote: > > > On Fri, Oct 13, 2006 at 09:41:35PM -0700, Andrew Morton wrote: > > > Bisection shows that this patch > > > (pci-check-that-mwi-bit-really-did-get-set.patch in Greg's PCI tree) > > > breaks > > > suspend-to-disk on my Vaio. It writes the suspend image and gets to the > > > point where it's supposed to power down, but doesn't. > > > > How odd. What driver is calling pci_set_mwi() on the suspend path? > > ehci_pci_reinit(). I stuck a dump_stack() in there. See > http://userweb.kernel.org/~akpm/s5000342.jpg
Thanks for the picture; that's really helpful. I see. We hibernate all the devices then wake them all back up again. No doubt there's a good reason for this. Still doesn't make much sense, though. As far as I can see, the only consequence of this particular patch is that 1) we do an additional read from PCI_COMMAND and 2) we can return -EINVAL in one additional case. But the only effect of returning EINVAL is a printk (for this particular driver): /* PCI Memory-Write-Invalidate cycle support is optional (uncommon) */ retval = pci_set_mwi(pdev); if (!retval) ehci_dbg(ehci, "MWI active\n"); ehci_port_power(ehci, 0); return 0; So even if we return EINVAL ... big deal. Is it possible reading PCI_COMMAND too quickly after writing it causes a foul-up? That would be weird ... so I suppose there's a few things I can ask you to try: 1. Stop reading the register back altogether. This should revert the behaviour to the prepatch state: - pci_read_config_word(dev, PCI_COMMAND, &cmd); +// pci_read_config_word(dev, PCI_COMMAND, &cmd); 2. Put an mdelay(1); before that line 3. Change the last line to just return 0. - return (cmd & PCI_COMMAND_INVALIDATE) ? 0 : -EINVAL; + return 0; > > What drivers do you have loaded on the Vaio? > > sony:/home/akpm> lsmod I don't see any of the other drivers calling pci_set_mwi, so i guess we're looking at the right suspect. I feel rather guilty about the amount of time you're spending on this; any bugs you want me to look at as penance? - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html