linux-kernel - Re: [PATCH] PCI / ACPI: Make acpiphp ignore root bridges using PCIe native hotplug

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Message-Id: <201110251525.27446.rjw@sisk.pl>
Date:	Tue, 25 Oct 2011 15:25:27 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	Linux PCI <linux-pci@...r.kernel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Mailing List <linux-acpi@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [PATCH] PCI / ACPI: Make acpiphp ignore root bridges using PCIe native hotplug

On Tuesday, October 25, 2011, Kenji Kaneshige wrote:
> Looks good.
> This is also needed for SHPC native hotplug.

I don't think so, we still leave the SHPC _OSC for the driver to take care
of (which may not be the right thing, but I don't feel confident enough to
decide :-)).

Thanks,
Rafael


> (2011/10/22 7:43), Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki<rjw@...k.pl>
> >
> > If the kernel has requested control of the PCIe native hotplug
> > feature for a given root complex, the acpiphp driver should not try
> > to handle that root complex and it should leave it to pciehp.
> > Failing to do so causes problems to happen if acpiphp is loaded
> > before pciehp on such systems.
> >
> > To address this issue make find_root_bridges() ignore PCIe root
> > complexes with PCIe native hotplug enabled and make add_bridge()
> > return error code if PCIe native hotplug is enabled for the given
> > root port.  This causes acpiphp to refuse to load if PCIe native
> > hotplug is enabled for all complexes and to refuse binding to
> > the root complexes with PCIe native hotplug is enabled.
> >
> > Signed-off-by: Rafael J. Wysocki<rjw@...k.pl>
> > ---
> >   drivers/pci/hotplug/acpiphp_glue.c |   29 ++++++++++++++++++++++++-----
> >   1 file changed, 24 insertions(+), 5 deletions(-)
> >
> > Index: linux/drivers/pci/hotplug/acpiphp_glue.c
> > ===================================================================
> > --- linux.orig/drivers/pci/hotplug/acpiphp_glue.c
> > +++ linux/drivers/pci/hotplug/acpiphp_glue.c
> > @@ -458,8 +458,17 @@ static int add_bridge(acpi_handle handle
> >   {
> >   	acpi_status status;
> >   	unsigned long long tmp;
> > +	struct acpi_pci_root *root;
> >   	acpi_handle dummy_handle;
> >
> > +	/*
> > +	 * We shouldn't use this bridge if PCIe native hotplug control has been
> > +	 * granted by the BIOS for it.
> > +	 */
> > +	root = acpi_pci_find_root(handle);
> > +	if (root&&  (root->osc_control_set&  OSC_PCI_EXPRESS_NATIVE_HP_CONTROL))
> > +		return -ENODEV;
> > +
> >   	/* if the bridge doesn't have _STA, we assume it is always there */
> >   	status = acpi_get_handle(handle, "_STA",&dummy_handle);
> >   	if (ACPI_SUCCESS(status)) {
> > @@ -1297,13 +1306,23 @@ static void handle_hotplug_event_func(ac
> >   static acpi_status
> >   find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
> >   {
> > +	struct acpi_pci_root *root;
> >   	int *count = (int *)context;
> >
> > -	if (acpi_is_root_bridge(handle)) {
> > -		acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> > -				handle_hotplug_event_bridge, NULL);
> > -			(*count)++;
> > -	}
> > +	if (!acpi_is_root_bridge(handle))
> > +		return AE_OK;
> > +
> > +	root = acpi_pci_find_root(handle);
> > +	if (!root)
> > +		return AE_OK;
> > +
> > +	if (root->osc_control_set&  OSC_PCI_EXPRESS_NATIVE_HP_CONTROL)
> > +		return AE_OK;
> > +
> > +	(*count)++;
> > +	acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
> > +				    handle_hotplug_event_bridge, NULL);
> > +
> >   	return AE_OK ;
> >   }
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> > the body of a message to majordomo@...r.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> 
> 
> 

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