Re: [PATCH V4 1/2] cpufreq: Mark x86 drivers with CPUFREQ_SKIP_INITIAL_FREQ_CHECK flag

Dirk Brandewie <dirk.brandewie@xxxxxxxxx> · Mon, 02 Dec 2013 07:23:01 -0800

Sorry for late response to these threads.  Holiday weekend in the US.

On 11/29/2013 06:14 AM, Viresh Kumar wrote:
On some systems we can't really say what frequency we're running at the moment
and so for these we shouldn't check if we are running at a frequency present in
frequency table. For now mark all x86 drivers with this flag:
CPUFREQ_SKIP_INITIAL_FREQ_CHECK.

This patch also defines this macro. It will be used in cpufreq.c in the next
patch.

Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
V3->V4:
- Reversed the order of patches
- Moved definition of CPUFREQ_SKIP_INITIAL_FREQ_CHECK to patch 1/2 instead of
   2/2.

  drivers/cpufreq/acpi-cpufreq.c       | 1 +
  drivers/cpufreq/cpufreq-nforce2.c    | 1 +
  drivers/cpufreq/e_powersaver.c       | 1 +
  drivers/cpufreq/elanfreq.c           | 1 +
  drivers/cpufreq/gx-suspmod.c         | 1 +
  drivers/cpufreq/ia64-acpi-cpufreq.c  | 1 +
  drivers/cpufreq/intel_pstate.c       | 2 +-

NAK for intel_pstate.  The code that will use this flag also uses has_target()
which is false for intel_pstate.

I think the logic for this patch is inverted. Why are we adding a flag to
drivers where the bug cannot exist? I would be happier if the flag was
CPUFREQ_NEED_INITIAL_FREQ_WORKAROUND to mark the platforms where the bug may 
exist let those platforms cary the flag for the next 10+ years.

I still believe that this bug should be dealt with in platform specific code
since this is working around a bootloader bug.  Are there platforms in the wild
that even need this code or is this to support early platform bringup?



  drivers/cpufreq/longhaul.c           | 1 +
  drivers/cpufreq/longrun.c            | 2 +-
  drivers/cpufreq/p4-clockmod.c        | 1 +
  drivers/cpufreq/pcc-cpufreq.c        | 2 +-
  drivers/cpufreq/powernow-k6.c        | 1 +
  drivers/cpufreq/powernow-k7.c        | 1 +
  drivers/cpufreq/powernow-k8.c        | 3 ++-
  drivers/cpufreq/sc520_freq.c         | 1 +
  drivers/cpufreq/speedstep-centrino.c | 1 +
  drivers/cpufreq/speedstep-ich.c      | 1 +
  drivers/cpufreq/speedstep-smi.c      | 1 +
  include/linux/cpufreq.h              | 9 +++++++++
  19 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index caf41eb..b8e4f79 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -903,6 +903,7 @@ static struct freq_attr *acpi_cpufreq_attr[] = {
  };

  static struct cpufreq_driver acpi_cpufreq_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= acpi_cpufreq_target,
  	.bios_limit	= acpi_processor_get_bios_limit,
diff --git a/drivers/cpufreq/cpufreq-nforce2.c b/drivers/cpufreq/cpufreq-nforce2.c
index a05b876..b3222f6 100644
--- a/drivers/cpufreq/cpufreq-nforce2.c
+++ b/drivers/cpufreq/cpufreq-nforce2.c
@@ -370,6 +370,7 @@ static int nforce2_cpu_exit(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver nforce2_driver = {
+	.flags = CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.name = "nforce2",
  	.verify = nforce2_verify,
  	.target = nforce2_target,
diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
index 9012b8b..0826bda 100644
--- a/drivers/cpufreq/e_powersaver.c
+++ b/drivers/cpufreq/e_powersaver.c
@@ -389,6 +389,7 @@ static int eps_cpu_exit(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver eps_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= eps_target,
  	.init		= eps_cpu_init,
diff --git a/drivers/cpufreq/elanfreq.c b/drivers/cpufreq/elanfreq.c
index de08acf..426d14d 100644
--- a/drivers/cpufreq/elanfreq.c
+++ b/drivers/cpufreq/elanfreq.c
@@ -194,6 +194,7 @@ __setup("elanfreq=", elanfreq_setup);


  static struct cpufreq_driver elanfreq_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.get		= elanfreq_get_cpu_frequency,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= elanfreq_target,
diff --git a/drivers/cpufreq/gx-suspmod.c b/drivers/cpufreq/gx-suspmod.c
index d83e826..7bfad48 100644
--- a/drivers/cpufreq/gx-suspmod.c
+++ b/drivers/cpufreq/gx-suspmod.c
@@ -438,6 +438,7 @@ static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)
   *   MediaGX/Geode GX initialize cpufreq driver
   */
  static struct cpufreq_driver gx_suspmod_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.get		= gx_get_cpuspeed,
  	.verify		= cpufreq_gx_verify,
  	.target		= cpufreq_gx_target,
diff --git a/drivers/cpufreq/ia64-acpi-cpufreq.c b/drivers/cpufreq/ia64-acpi-cpufreq.c
index 53c6ac6..907bf9a 100644
--- a/drivers/cpufreq/ia64-acpi-cpufreq.c
+++ b/drivers/cpufreq/ia64-acpi-cpufreq.c
@@ -344,6 +344,7 @@ acpi_cpufreq_cpu_exit (


  static struct cpufreq_driver acpi_cpufreq_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify 	= cpufreq_generic_frequency_table_verify,
  	.target_index	= acpi_cpufreq_target,
  	.get 		= acpi_cpufreq_get,
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 5f1cbae..6c8f5d3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -725,7 +725,7 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver intel_pstate_driver = {
-	.flags		= CPUFREQ_CONST_LOOPS,
+	.flags		= CPUFREQ_CONST_LOOPS | CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= intel_pstate_verify_policy,
  	.setpolicy	= intel_pstate_set_policy,
  	.get		= intel_pstate_get,
diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c
index 45bafdd..16c0a37 100644
--- a/drivers/cpufreq/longhaul.c
+++ b/drivers/cpufreq/longhaul.c
@@ -909,6 +909,7 @@ static int longhaul_cpu_init(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver longhaul_driver = {
+	.flags	= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify	= cpufreq_generic_frequency_table_verify,
  	.target_index = longhaul_target,
  	.get	= longhaul_get,
diff --git a/drivers/cpufreq/longrun.c b/drivers/cpufreq/longrun.c
index 074971b..b67d341 100644
--- a/drivers/cpufreq/longrun.c
+++ b/drivers/cpufreq/longrun.c
@@ -278,7 +278,7 @@ static int longrun_cpu_init(struct cpufreq_policy *policy)


  static struct cpufreq_driver longrun_driver = {
-	.flags		= CPUFREQ_CONST_LOOPS,
+	.flags		= CPUFREQ_CONST_LOOPS | CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= longrun_verify_policy,
  	.setpolicy	= longrun_set_policy,
  	.get		= longrun_get,
diff --git a/drivers/cpufreq/p4-clockmod.c b/drivers/cpufreq/p4-clockmod.c
index 3d1cba9..92b7e2b 100644
--- a/drivers/cpufreq/p4-clockmod.c
+++ b/drivers/cpufreq/p4-clockmod.c
@@ -234,6 +234,7 @@ static unsigned int cpufreq_p4_get(unsigned int cpu)
  }

  static struct cpufreq_driver p4clockmod_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= cpufreq_p4_target,
  	.init		= cpufreq_p4_cpu_init,
diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c
index e2b4f40..eafe4ca 100644
--- a/drivers/cpufreq/pcc-cpufreq.c
+++ b/drivers/cpufreq/pcc-cpufreq.c
@@ -571,7 +571,7 @@ static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver pcc_cpufreq_driver = {
-	.flags = CPUFREQ_CONST_LOOPS,
+	.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.get = pcc_get_freq,
  	.verify = pcc_cpufreq_verify,
  	.target = pcc_cpufreq_target,
diff --git a/drivers/cpufreq/powernow-k6.c b/drivers/cpufreq/powernow-k6.c
index 643e795..fe60021 100644
--- a/drivers/cpufreq/powernow-k6.c
+++ b/drivers/cpufreq/powernow-k6.c
@@ -150,6 +150,7 @@ static unsigned int powernow_k6_get(unsigned int cpu)
  }

  static struct cpufreq_driver powernow_k6_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= powernow_k6_target,
  	.init		= powernow_k6_cpu_init,
diff --git a/drivers/cpufreq/powernow-k7.c b/drivers/cpufreq/powernow-k7.c
index 946708a..4e67abc 100644
--- a/drivers/cpufreq/powernow-k7.c
+++ b/drivers/cpufreq/powernow-k7.c
@@ -679,6 +679,7 @@ static int powernow_cpu_exit(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver powernow_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= powernow_target,
  	.get		= powernow_get,
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 0023c7d..ffe89ba 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -1204,7 +1204,8 @@ out:
  }

  static struct cpufreq_driver cpufreq_amd64_driver = {
-	.flags		= CPUFREQ_ASYNC_NOTIFICATION,
+	.flags		= CPUFREQ_ASYNC_NOTIFICATION |
+				CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= powernowk8_target,
  	.bios_limit	= acpi_processor_get_bios_limit,
diff --git a/drivers/cpufreq/sc520_freq.c b/drivers/cpufreq/sc520_freq.c
index 6adb354..d6a1cf6 100644
--- a/drivers/cpufreq/sc520_freq.c
+++ b/drivers/cpufreq/sc520_freq.c
@@ -89,6 +89,7 @@ static int sc520_freq_cpu_init(struct cpufreq_policy *policy)


  static struct cpufreq_driver sc520_freq_driver = {
+	.flags	= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.get	= sc520_freq_get_cpu_frequency,
  	.verify	= cpufreq_generic_frequency_table_verify,
  	.target_index = sc520_freq_target,
diff --git a/drivers/cpufreq/speedstep-centrino.c b/drivers/cpufreq/speedstep-centrino.c
index 4e1daca..887fd43 100644
--- a/drivers/cpufreq/speedstep-centrino.c
+++ b/drivers/cpufreq/speedstep-centrino.c
@@ -505,6 +505,7 @@ out:
  }

  static struct cpufreq_driver centrino_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.name		= "centrino", /* should be speedstep-centrino,
  					 but there's a 16 char limit */
  	.init		= centrino_cpu_init,
diff --git a/drivers/cpufreq/speedstep-ich.c b/drivers/cpufreq/speedstep-ich.c
index 7639b2b..67596e7 100644
--- a/drivers/cpufreq/speedstep-ich.c
+++ b/drivers/cpufreq/speedstep-ich.c
@@ -307,6 +307,7 @@ static int speedstep_cpu_init(struct cpufreq_policy *policy)


  static struct cpufreq_driver speedstep_driver = {
+	.flags	= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.name	= "speedstep-ich",
  	.verify	= cpufreq_generic_frequency_table_verify,
  	.target_index = speedstep_target,
diff --git a/drivers/cpufreq/speedstep-smi.c b/drivers/cpufreq/speedstep-smi.c
index 0f5326d..4f23289 100644
--- a/drivers/cpufreq/speedstep-smi.c
+++ b/drivers/cpufreq/speedstep-smi.c
@@ -308,6 +308,7 @@ static int speedstep_resume(struct cpufreq_policy *policy)
  }

  static struct cpufreq_driver speedstep_driver = {
+	.flags		= CPUFREQ_SKIP_INITIAL_FREQ_CHECK,
  	.name		= "speedstep-smi",
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= speedstep_target,
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index ee5fe9d..13b8802 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -252,6 +252,15 @@ struct cpufreq_driver {
   */
  #define CPUFREQ_ASYNC_NOTIFICATION  (1 << 4)

+/*
+ * Set by drivers which don't want cpufreq core to check if CPU is running at a
+ * frequency present in freq-table exposed by the driver. For other drivers if
+ * CPU is found running at an out of table freq, we will try to set it to a freq
+ * from the table. And if that fails, we will stop further boot process by
+ * issuing a BUG_ON().
+ */
+#define CPUFREQ_SKIP_INITIAL_FREQ_CHECK	(1 << 5)
+
  int cpufreq_register_driver(struct cpufreq_driver *driver_data);
  int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);



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