On Thursday, May 14, 2015 10:36:52 PM Rafael J. Wysocki wrote:
> On Thursday, May 14, 2015 03:31:26 PM Dominik Brodowski wrote:
> > By using a module parameter named acpi.supported_rev=<value>, the BIOS
> > may be told a different supported ACPI revision compared to the default
> > (which currently is 5, but will be modified to 2 when the revert of
> > b1ef29725865 is reverted).
> >
> > Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
> > ---
> > Documentation/kernel-parameters.txt | 14 ++++++++++++++
> > drivers/acpi/osl.c | 16 ++++++++++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> > index 61ab162..75f1f8e 100644
> > --- a/Documentation/kernel-parameters.txt
> > +++ b/Documentation/kernel-parameters.txt
> > @@ -335,6 +335,20 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> > to assume that this machine's pmtimer latches its value
> > and always returns good values.
> >
> > + acpi.rev= [HW,ACPI]
> > + Tell ACPI BIOS the supported ACPI REV
> > + Format: <int> in range 0..5
> > + Up to and including Linux v4.1, the BIOS was told which
> > + ACPI revision the ACPICA subsystem in Linux actually
> > + supports (which was 5 at the time); from v4.2 on, this
> > + value will be set statically to 2 to match the behavior
> > + of other ACPI implementations. As some BIOS may operate
> > + differently depending on which value _REV is set to, this
> > + parameter offers the capability to specify what to export
> > + to the BIOS. Note that such changes in the behavior of
> > + the BIOS may only be visible after cold booting the
> > + system with this parameter _twice_.
> > +
> > acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
> > Format: { level | edge | high | low }
> >
> > diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> > index db14a66..caa52f7 100644
> > --- a/drivers/acpi/osl.c
> > +++ b/drivers/acpi/osl.c
> > @@ -538,6 +538,11 @@ acpi_os_get_physical_address(void *virt, acpi_physical_address * phys)
> >
> > static char acpi_os_name[ACPI_MAX_OVERRIDE_LEN];
> >
> > +/* acpi_supported_rev is 0 in case of no override; overrides are limited to
> > + * values between 1 to 5. To simplify casting, use an unsigned long */
> > +static unsigned long acpi_supported_rev;
> > +module_param_named(rev, acpi_supported_rev, ulong, 0);
> > +
> > acpi_status
> > acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
> > char **new_val)
> > @@ -552,6 +557,17 @@ acpi_os_predefined_override(const struct acpi_predefined_names *init_val,
> > *new_val = acpi_os_name;
> > }
> >
> > + if (!memcmp(init_val->name, "_REV", 4) && (acpi_supported_rev > 0)) {
> > + if (acpi_supported_rev <= 5) {
>
> So the only value that would really make sense here is 5.
>
> 1 should never ever be used with Linux, 2 is the default, 3 is equivalent to 5
> for all practical purposes and 4 has never been used in practice, so it is
> meaningless.
>
> I'd be better to rename the command line switch to acpi.rev_override and
> simply do "acpi_supported_rev = 5" for it as well as in acpi_set_supported_rev()
> in [3/4].
>
> > + printk(KERN_INFO PREFIX
> > + "Overriding _REV definition to %lu\n",
> > + acpi_supported_rev);
> > + *new_val = (char *) acpi_supported_rev;
> > + } else
> > + printk(KERN_INFO PREFIX
> > + "_REV override must be between 1 to 5");
> > + }
> > +
> > return AE_OK;
> > }
Overall, what about the appended patch instead of your [2-3/4] (modulo the new
command line parameter description which is missing here ATM)?
---
drivers/acpi/Kconfig | 22 ++++++++++++++++++++++
drivers/acpi/blacklist.c | 26 ++++++++++++++++++++++++++
drivers/acpi/internal.h | 4 ++++
drivers/acpi/osl.c | 18 ++++++++++++++++++
4 files changed, 70 insertions(+)
Index: linux-pm/drivers/acpi/blacklist.c
===================================================================
--- linux-pm.orig/drivers/acpi/blacklist.c
+++ linux-pm/drivers/acpi/blacklist.c
@@ -162,6 +162,15 @@ static int __init dmi_disable_osi_win8(c
acpi_osi_setup("!Windows 2012");
return 0;
}
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+static int __init dmi_enable_rev_override(const struct dmi_system_id *d)
+{
+ printk(KERN_NOTICE PREFIX "DMI detected: %s (force ACPI _REV to 5)\n",
+ d->ident);
+ acpi_rev_override_setup(NULL);
+ return 0;
+}
+#endif
static struct dmi_system_id acpi_osi_dmi_table[] __initdata = {
{
@@ -325,6 +334,23 @@ static struct dmi_system_id acpi_osi_dmi
DMI_MATCH(DMI_PRODUCT_NAME, "1015PX"),
},
},
+
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+ /*
+ * DELL XPS 13 (2015) switches sound between HDA and I2S
+ * depending on the ACPI _REV callback. If userspace supports
+ * I2S sufficiently (or if you do not care about sound), you
+ * can safely disable this quirk.
+ */
+ {
+ .callback = dmi_enable_rev_override,
+ .ident = "DELL XPS 13 (2015)",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+ DMI_MATCH(DMI_PRODUCT_NAME, "XPS 13 9343"),
+ },
+ },
+#endif
{}
};
Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -23,6 +23,10 @@
#define PREFIX "ACPI: "
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+int __init acpi_rev_override_setup(char *str);
+#endif
+
acpi_status acpi_os_initialize1(void);
int init_acpi_device_notify(void);
int acpi_scan_init(void);
Index: linux-pm/drivers/acpi/osl.c
===================================================================
--- linux-pm.orig/drivers/acpi/osl.c
+++ linux-pm/drivers/acpi/osl.c
@@ -534,6 +534,19 @@ acpi_os_get_physical_address(void *virt,
}
#endif
+#ifdef CONFIG_ACPI_REV_OVERRIDE_POSSIBLE
+static bool acpi_rev_override;
+
+int __init acpi_rev_override_setup(char *str)
+{
+ acpi_rev_override = true;
+ return 1;
+}
+__setup("acpi_rev_override", acpi_rev_override_setup);
+#else
+#define acpi_rev_override false
+#endif
+
#define ACPI_MAX_OVERRIDE_LEN 100
static char acpi_os_name[ACPI_MAX_OVERRIDE_LEN];
@@ -552,6 +565,11 @@ acpi_os_predefined_override(const struct
*new_val = acpi_os_name;
}
+ if (!memcmp(init_val->name, "_REV", 4) && acpi_rev_override) {
+ printk(KERN_INFO PREFIX "Overriding _REV return value to 5\n");
+ *new_val = (char *)5;
+ }
+
return AE_OK;
}
Index: linux-pm/drivers/acpi/Kconfig
===================================================================
--- linux-pm.orig/drivers/acpi/Kconfig
+++ linux-pm/drivers/acpi/Kconfig
@@ -428,6 +428,28 @@ config XPOWER_PMIC_OPREGION
help
This config adds ACPI operation region support for XPower AXP288 PMIC.
++config ACPI_REV_OVERRIDE_POSSIBLE
+ bool "Allow supported ACPI revision to be overriden"
+ depends on X86
+ default y
+ help
+ The platform firmware on some systems expects Linux to return "5" as
+ the supported ACPI revision which makes it expose system configuration
+ information in a special way.
+
+ For example, based on what ACPI exports as the supported revision,
+ Dell XPS 13 (2015) configures its audio device to either work in HDA
+ mode or in I2S mode, where the former is supposed to be used on Linux
+ until the latter is fully supported (in the kernel as well as in user
+ space).
+
+ This option enables a DMI-based quirk for the above Dell machine (so
+ that HDA audio is exposed by the platform firmware to the kernel) and
+ makes it possible to force the kernel to return "5" as the supported
+ ACPI revision via the "acpi_rev_override" command line switch (when
+ using that switch it may be necessary to carry out a cold reboot
+ _twice_ in a row to make it take effect on the firmware).
+
endif
endif # ACPI
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