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SubjectRe: [PATCH 3/3] PCI Hotplug: workaround for Thunderbolt on Intel DZ77RE-75K motherboard
On Thu, Dec 13, 2012 at 10:48:20AM -0800, Greg KH wrote:
> On Thu, Dec 13, 2012 at 05:31:48PM +0200, Kirill A. Shutemov wrote:
> > From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> >
> > BIOS on Intel DZ77RE-75K motherboard notifies OS about Thunderbolt
> > hotplug before devices behind Thunderbolt are ready to be enumerated.
> >
> > Let's delay enumeration by 2 seconds.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > ---
> > drivers/pci/hotplug/acpiphp_glue.c | 16 +++++++++++++++-
> > 1 file changed, 15 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
> > index 1a2b3ca..165987a 100644
> > --- a/drivers/pci/hotplug/acpiphp_glue.c
> > +++ b/drivers/pci/hotplug/acpiphp_glue.c
> > @@ -49,6 +49,7 @@
> > #include <linux/mutex.h>
> > #include <linux/slab.h>
> > #include <linux/acpi.h>
> > +#include <linux/dmi.h>
> >
> > #include "../pci.h"
> > #include "acpiphp.h"
> > @@ -1327,6 +1328,19 @@ out:
> > static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
> > void *context)
> > {
> > + unsigned long delay = 0;
> > + const char *board_name;
> > +
> > + board_name = dmi_get_system_info(DMI_BOARD_NAME);
> > + /*
> > + * BIOS on Intel DZ77RE-75K motherboard notifies OS about Thunderbolt
> > + * hotplug before devices behind Thunderbolt are ready to be
> > + * enumerated.
> > + * Let's delay enumeration by 2 seconds.
> > + */
> > + if (board_name && !strcmp(board_name, "DZ77RE-75K"))
> > + delay = 2 * HZ;
>
> Again, no objection to this patch as-is, but should we make it a bit
> more "general" and provide a quirk table to make this type of fix easier
> for other motherboards? Shouldn't we also match on a manufacturer field
> as well as the board_name? The kernel provides a very easy to match on
> any arbritary set of DMI fields for this kind of problem that we could
> use here.

Something like this (untested):

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index 1a2b3ca..c4db634 100644
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -49,6 +49,7 @@
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/acpi.h>
+#include <linux/dmi.h>

#include "../pci.h"
#include "acpiphp.h"
@@ -1327,6 +1328,31 @@ out:
static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
void *context)
{
+ unsigned long delay = 0;
+ const struct dmi_system_id *match;
+ static const struct dmi_system_id sysids[] = {
+ /*
+ * BIOS on Intel DZ77RE-75K motherboard notifies OS about
+ * Thunderbolt hotplug before devices behind Thunderbolt are
+ * ready to be enumerated.
+ * Let's delay enumeration by 2 seconds.
+ */
+ {
+ .ident = "DZ77RE-75K",
+ .matches = {
+ DMI_MATCH(DMI_BOARD_VENDOR,
+ "Intel Corporation"),
+ DMI_MATCH(DMI_BOARD_NAME,
+ "DZ77RE-75K"),
+ },
+ .driver_data = (void *) (2 * HZ), /* delay */
+ },
+ };
+
+ match = dmi_first_match(sysids);
+ if (match)
+ delay = (unsigned long) match->driver_data;
+
/*
* Currently the code adds all hotplug events to the kacpid_wq
* queue when it should add hotplug events to the kacpi_hotplug_wq.
@@ -1336,7 +1362,7 @@ static void handle_hotplug_event_bridge(acpi_handle handle, u32 type,
* don't deadlock on hotplug actions.
*/
alloc_acpiphp_hp_work(handle, type, context,
- _handle_hotplug_event_bridge, 0);
+ _handle_hotplug_event_bridge, delay);
}

static void _handle_hotplug_event_func(struct work_struct *work)
--
Kirill A. Shutemov
[unhandled content-type:application/pgp-signature]
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