linux-kernel - Re: [PATCH 3.13 08/32] PCI: Enable INTx in pci_reenable

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Message-ID: <1398090269.3624.116.camel@deadeye.wl.decadent.org.uk>
Date:	Mon, 21 Apr 2014 15:24:29 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>
Subject: Re: [PATCH 3.13 08/32] PCI: Enable INTx in pci_reenable_device()
 only when MSI/MSI-X not enabled

On Sun, 2014-04-20 at 19:13 -0700, Greg Kroah-Hartman wrote:
> 3.13-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> commit 866d54177b4e671cd52bed1fb487d140d7b691f5 upstream.
> 
> Andreas reported that after 1f42db786b14 ("PCI: Enable INTx if BIOS left
> them disabled"), pciehp surprise removal stopped working.
> 
> This happens because pci_reenable_device() on the hotplug bridge (used in
> the pciehp_configure_device() path) clears the Interrupt Disable bit, which
> apparently breaks the bridge's MSI hotplug event reporting.
> 
> Previously we cleared the Interrupt Disable bit in do_pci_enable_device(),
> which is used by both pci_enable_device() and pci_reenable_device().  But
> we use pci_reenable_device() after the driver may have enabled MSI or
> MSI-X, and we *set* Interrupt Disable as part of enabling MSI/MSI-X.
> 
> This patch clears Interrupt Disable only when MSI/MSI-X has not been
> enabled.
> 
> Fixes: 1f42db786b14 PCI: Enable INTx if BIOS left them disabled
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=71691
> Reported-and-tested-by: Andreas Noever <andreas.noever@...il.com>
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> CC: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> 
> ---
>  drivers/pci/pci.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1134,6 +1134,9 @@ static int do_pci_enable_device(struct p
>  	if (dev->msi_enabled || dev->msix_enabled)
>  		return 0;
>  
> +	if (dev->msi_enabled || dev->msix_enabled)
> +		return 0;
> +

This fix seems to have been applied to two upstream branches and you
have already applied one instance.

Ben.

>  	pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
>  	if (pin) {
>  		pci_read_config_word(dev, PCI_COMMAND, &cmd);
> 
> 
> --
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-- 
Ben Hutchings
Knowledge is power.  France is bacon.

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