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    SubjectRe: [PATCH 3/3] intel_pstate: add module and kernel command line parameter to ignore ACPI _PPC
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    > 在 2014年11月20日,03:05,Kristen Carlson Accardi <kristen@linux.intel.com> 写道:
    >
    > On Tue, 18 Nov 2014 17:37:06 +0900
    > Ethan Zhao <ethan.zhao@oracle.com> wrote:
    >
    >> Add kernel command line parameter
    >> intel_pstate = ignore_acpi_ppc
    >> and module parameter
    >> ignore_acpi_ppc = 1
    >> to allow driver to ignore the ACPI _PPC existence even for Sun x86 servers.
    >> These parameter could be used for debug\test\workaround etc purpose.
    >>
    >> Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>
    >
    > What if we used a more generic parameter like "force" that would bypass
    > any vendor specific checks and just load anyway? This way we don't have
    > to add new parameters everything some new thing shows up that we want to
    > ignore.
    >
    To be honest, I prefer more generic parameter. But to avoid the possible negative affect
    To another vendors. I back to this way.

    Thanks,
    Ethan
    >> ---
    >> Documentation/kernel-parameters.txt | 3 +++
    >> drivers/cpufreq/intel_pstate.c | 8 +++++++-
    >> 2 files changed, 10 insertions(+), 1 deletion(-)
    >>
    >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
    >> index 4c81a86..f502b85 100644
    >> --- a/Documentation/kernel-parameters.txt
    >> +++ b/Documentation/kernel-parameters.txt
    >> @@ -1446,6 +1446,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
    >> disable
    >> Do not enable intel_pstate as the default
    >> scaling driver for the supported processors
    >> + ignore_acpi_ppc
    >> + Ignore the existence of ACPI method _PPC for Sun x86 servers
    >> + and load the driver.
    >>
    >> intremap= [X86-64, Intel-IOMMU]
    >> on enable Interrupt Remapping (default)
    >> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
    >> index 7c5faea..388387b 100644
    >> --- a/drivers/cpufreq/intel_pstate.c
    >> +++ b/drivers/cpufreq/intel_pstate.c
    >> @@ -870,6 +870,7 @@ static struct cpufreq_driver intel_pstate_driver = {
    >> };
    >>
    >> static int __initdata no_load;
    >> +static unsigned int ignore_acpi_ppc;
    >>
    >> static int intel_pstate_msrs_not_valid(void)
    >> {
    >> @@ -990,7 +991,7 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
    >> intel_pstate_no_acpi_pss())
    >> return true;
    >> if (!strncmp(hdr.oem_id, v_info->oem_id, ACPI_OEM_ID_SIZE) &&
    >> - intel_pstate_has_acpi_ppc())
    >> + intel_pstate_has_acpi_ppc() && !ignore_acpi_ppc)
    >> return true;
    >> }
    >>
    >> @@ -1066,11 +1067,16 @@ static int __init intel_pstate_setup(char *str)
    >>
    >> if (!strcmp(str, "disable"))
    >> no_load = 1;
    >> + if (!strcmp(str, "ignore_acpi_ppc"))
    >> + ignore_acpi_ppc = 1;
    >> return 0;
    >> }
    >> early_param("intel_pstate", intel_pstate_setup);
    >> #endif
    >>
    >> +module_param(ignore_acpi_ppc, uint, 0644);
    >> +MODULE_PARM_DESC(ignore_acpi_ppc,
    >> + "value 0 or non-zero. non-zero -> ignore ACPI _PPC and load this driver");
    >> MODULE_AUTHOR("Dirk Brandewie <dirk.j.brandewie@intel.com>");
    >> MODULE_DESCRIPTION("'intel_pstate' - P state driver Intel Core processors");
    >> MODULE_LICENSE("GPL");
    >


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