Re: [PATCH v2 6/8] PCI: acpiphp: workaround for Thunderbolt on Acer Aspire S5

From: Rafael J. Wysocki
Date: Thu Jul 04 2013 - 09:44:21 EST

Next message: Ramkumar Ramachandra: "[PATCH 0/2] Minor perf build fixes"
Previous message: Wei Yongjun: "[PATCH] ncpfs: fix error return code in ncp_parse_options()"
In reply to: Mika Westerberg: "Re: [PATCH v2 6/8] PCI: acpiphp: workaround for Thunderbolt on AcerAspire S5"
Next in thread: Mika Westerberg: "[PATCH v2.1 6/8] PCI: acpiphp: workaround for Thunderbolt on Acer Aspire S5"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Thursday, July 04, 2013 04:33:14 PM Mika Westerberg wrote:
> On Thu, Jul 04, 2013 at 03:14:58PM +0200, Rafael J. Wysocki wrote:
> > On Thursday, July 04, 2013 03:53:38 PM Mika Westerberg wrote:
> > > On Thu, Jul 04, 2013 at 02:36:00PM +0200, Rafael J. Wysocki wrote:
> > > > On Thursday, July 04, 2013 11:58:44 AM Mika Westerberg wrote:
> > > > > On Wed, Jul 03, 2013 at 11:40:42PM +0200, Rafael J. Wysocki wrote:
> > > > > > On Wednesday, July 03, 2013 05:04:53 PM Mika Westerberg wrote:
> > > > > > > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> > > > > > >
> > > > > > > Correct ACPI PCI hotplug imeplementation should have _RMV method in a
> > > > > > > PCI slot (device under pci bridge). In Acer Aspire S5 case we have it
> > > > > > > deeper in hierarchy:
> > > > > > >
> > > > > > > Device (RP05)
> > > > > > > {
> > > > > > > // ...
> > > > > > > Device (HRUP)
> > > > > > > {
> > > > > > > // ...
> > > > > > > Device (HRDN)
> > > > > > > {
> > > > > > > // ...
> > > > > > > Device (EPUP)
> > > > > > > {
> > > > > > > // ...
> > > > > > > Method (_RMV, 0, NotSerialized) // _RMV: Removal Status
> > > > > > > {
> > > > > > > Return (One)
> > > > > > > }
> > > > > > > }
> > > > > > > }
> > > > > > > }
> > > > > > > }
> > > > > > >
> > > > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > > > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > > > > > > ---
> > > > > > > drivers/pci/hotplug/acpi_pcihp.c | 13 +++++++++++++
> > > > > > > 1 file changed, 13 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
> > > > > > > index 2a47e82..d92ebfb 100644
> > > > > > > --- a/drivers/pci/hotplug/acpi_pcihp.c
> > > > > > > +++ b/drivers/pci/hotplug/acpi_pcihp.c
> > > > > > > @@ -422,6 +422,19 @@ static int pcihp_is_ejectable(acpi_handle handle)
> > > > > > > status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
> > > > > > > if (ACPI_SUCCESS(status) && removable)
> > > > > > > return 1;
> > > > > > > +
> > > > > > > + /*
> > > > > > > + * Workaround for Thunderbolt implementation on Acer Aspire S5.
> > > > > > > + *
> > > > > > > + * Correct ACPI PCI hotplug imeplementation has _RMV method in a PCI
> > > > > > > + * slot (device under pci bridge). In Acer Aspire S5 case we have it
> > > > > > > + * deeper in hierarchy.
> > > > > > > + */
> > > > > > > + status = acpi_evaluate_integer(handle, "HRDN.EPUP._RMV", NULL,
> > > > > > > + &removable);
> > > > > >
> > > > > > Well, calling stuff like this directly from a general function is kind of ugly.
> > > > > >
> > > > > > Can we use something like a quirk instead? A DMI check or something?
> > > > >
> > > > > Sure we can. How about something like the patch below?
> > > >
> > > > Well, it goes into the right (to me) direction. :-)
> > > >
> > > > Some comments below.
> > > >
> > > > > From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > > > > Subject: [PATCH] PCI: acpiphp: workaround for Thunderbolt on Acer Aspire S5
> > > > >
> > > > > The acpiphp driver finds out whether the device is removable by checking
> > > > > whether it has _RMV method directly behind it (and if it returns 1).
> > > > > However, at least on Acer Aspire S5 with Thunderbolt host router has this
> > > > > method placed behind a device called EPUP (endpoint upstream port?) and not
> > > > > in the usual place expected by the acpiphp driver. The ASL code below shows
> > > > > how this is done on that machine:
> > > > >
> > > > > Device (RP05)
> > > > > {
> > > > > ...
> > > > > Device (HRUP)
> > > > > {
> > > > > Name (_ADR, Zero)
> > > > > Name (_PRW, Package (0x02)
> > > > > {
> > > > > 0x09,
> > > > > 0x04
> > > > > })
> > > > > Device (HRDN)
> > > > > {
> > > > > Name (_ADR, 0x00040000)
> > > > > Name (_PRW, Package (0x02)
> > > > > {
> > > > > 0x09,
> > > > > 0x04
> > > > > })
> > > > > Device (EPUP)
> > > > > {
> > > > > Name (_ADR, Zero)
> > > > > Method (_RMV, 0, NotSerialized)
> > > > > {
> > > > > Return (One)
> > > > > }
> > > > > }
> > > > > }
> > > > > }
> > > > > ...
> > > > >
> > > > > Fix this by adding a DMI quirk for the Acer Aspire S5 machine that gives an
> > > > > alternative path to the _RMV method.
> > > > >
> > > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> > > > > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > > > > ---
> > > > > drivers/pci/hotplug/acpi_pcihp.c | 57 ++++++++++++++++++++++++++++++++++++----
> > > > > 1 file changed, 52 insertions(+), 5 deletions(-)
> > > > >
> > > > > diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
> > > > > index 2a47e82..99fccf3 100644
> > > > > --- a/drivers/pci/hotplug/acpi_pcihp.c
> > > > > +++ b/drivers/pci/hotplug/acpi_pcihp.c
> > > > > @@ -33,6 +33,7 @@
> > > > > #include <linux/acpi.h>
> > > > > #include <linux/pci-acpi.h>
> > > > > #include <linux/slab.h>
> > > > > +#include <linux/dmi.h>
> > > > >
> > > > > #define MY_NAME "acpi_pcihp"
> > > > >
> > > > > @@ -408,21 +409,67 @@ got_one:
> > > > > }
> > > > > EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
> > > > >
> > > > > +/**
> > > > > + * pcihp_is_removable - is the given ACPI device removable
> > > > > + * @handle: ACPI handle of the device
> > > > > + *
> > > > > + * Try to find out whether the given ACPI device is removable by evaluating
> > > > > + * its _RMV and returning the result. If we can't find the _RMV directly
> > > > > + * under the device use system specific quirks to locate it.
> > > > > + */
> > > > > +static bool pcihp_is_removable(acpi_handle handle)
> > > > > +{
> > > >
> > > > People are generally used to seeing DMI lists outside of functions.
> > >
> > > OK.
> > >
> > > > > + static const struct dmi_system_id rmv_paths[] = {
> > > > > + {
> > > > > + /*
> > > > > + * On Acer Aspire S5 the _RMV method for the
> > > > > + * Thunderbolt host router upstream port is not
> > > > > + * located directly under the device but it is
> > > > > + * instead placed a bit deeper in the hierarchy.
> > > > > + */
> > > > > + .ident = "Acer Aspire S5",
> > > > > + .matches = {
> > > > > + DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
> > > > > + DMI_MATCH(DMI_PRODUCT_NAME, "Aspire S5-391"),
> > > > > + },
> > > > > + .driver_data = "HRDN.EPUP._RMV",
> > > >
> > > > Use .callback instead? ->
> > > >
> > > > > + },
> > > > > + { }
> > > > > + };
> > > > > + const struct dmi_system_id *id;
> > > > > + unsigned long long removable;
> > > > > + acpi_status status;
> > > > > +
> > > > > + status = acpi_evaluate_integer(handle, "_RMV", NULL, &removable);
> > > > > + if (ACPI_SUCCESS(status))
> > > > > + return !!removable;
> > > > > +
> > > > > + /* Try system specific quirks */
> > > > > + id = dmi_first_match(rmv_paths);
> > > > > + if (id && id->driver_data) {
> > > >
> > > > -> And here do
> > > >
> > > > if (id && id->callback)
> > > > return id->callback(id);
> > >
> > > There is a problem with the above that we can't pass an ACPI handle to the
> > > callback function.
> >
> > Ah, right.
> >
> > Well, you can do
> >
> > if (id && id->driver_data) {
> > bool (*callback)(acpi_handle) = id->driver_data;
> >
> > return callback(handle);
> > }
> >
> > although it's a bit hackish.
>
> I'm thinking that passing just the path from driver_data might be simpler
> in this case ;-) But I'm fine with changing it to be a callback as well.

No, it probably isn't worth the effort for just one system.

> > > >
> > > > > + char path[64];
> > > > > +
> > > > > + strlcpy(path, id->driver_data, sizeof(path));
> >
> > BTW, why didn't you want to pass id->driver_data directly here?
>
> acpi_evaluate_integer() takes acpi_string as parameter which is 'char *',
> not 'const char *'.
>
> Doing:
>
> .driver_data = "HRDN.EPUP._RMV",
>
> might place that string to a read-only area (as it is constant), if I
> understand C correctly. So even though I know that acpi_evaluate_interger()
> doesn't change the parameter, there's no guarantee that it doesn't do that
> in the future.

I think you can safely assume that acpi_evaluate_integer() won't try to modify
path (there are too many places where string literals are passed to it).

IOW, please just pass id->driver_data to it.

>
> >
> > > > > + status = acpi_evaluate_integer(handle, path, NULL, &removable);
> > > > > + if (ACPI_SUCCESS(status))
> > > > > + return !!removable;
> > > > > + }
> > > > > +
> > > > > + return false;
> > > > > +}
> > > > > +

Thanks,
Rafael

--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

Next message: Ramkumar Ramachandra: "[PATCH 0/2] Minor perf build fixes"
Previous message: Wei Yongjun: "[PATCH] ncpfs: fix error return code in ncp_parse_options()"
In reply to: Mika Westerberg: "Re: [PATCH v2 6/8] PCI: acpiphp: workaround for Thunderbolt on AcerAspire S5"
Next in thread: Mika Westerberg: "[PATCH v2.1 6/8] PCI: acpiphp: workaround for Thunderbolt on Acer Aspire S5"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]