cpufreq: longhaul: Fix double invocation of cpufreq_freq_transition_begin/end
During frequency transitions, the cpufreq core takes the responsibility of
invoking cpufreq_freq_transition_begin() and cpufreq_freq_transition_end()
for those cpufreq drivers that define the ->target_index callback but don't
set the ASYNC_NOTIFICATION flag.
The longhaul cpufreq driver falls under this category, but this driver was
invoking the _begin() and _end() APIs itself around frequency transitions,
which led to double invocation of the _begin() API. The _begin API makes
contending callers wait until the previous invocation is complete. Hence,
the longhaul driver ended up waiting on itself, leading to system hangs
during boot.
Fix this by removing the calls to the _begin() and _end() APIs from the
longhaul driver, since they rightly belong to the cpufreq core.
(Note that during module_exit(), the longhaul driver sets the frequency
without any help from the cpufreq core. So add explicit calls to the
_begin() and _end() APIs around that frequency transition alone, to take
care of that special case.)
Fixes: 12478cf0c55e (cpufreq: Make sure frequency transitions are serialized)
Reported-and-tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/longhaul.c b/drivers/cpufreq/longhaul.c
index d00e5d1..5c4369b 100644
--- a/drivers/cpufreq/longhaul.c
+++ b/drivers/cpufreq/longhaul.c
@@ -242,7 +242,7 @@
* Sets a new clock ratio.
*/
-static void longhaul_setstate(struct cpufreq_policy *policy,
+static int longhaul_setstate(struct cpufreq_policy *policy,
unsigned int table_index)
{
unsigned int mults_index;
@@ -258,10 +258,12 @@
/* Safety precautions */
mult = mults[mults_index & 0x1f];
if (mult == -1)
- return;
+ return -EINVAL;
+
speed = calc_speed(mult);
if ((speed > highest_speed) || (speed < lowest_speed))
- return;
+ return -EINVAL;
+
/* Voltage transition before frequency transition? */
if (can_scale_voltage && longhaul_index < table_index)
dir = 1;
@@ -269,8 +271,6 @@
freqs.old = calc_speed(longhaul_get_cpu_mult());
freqs.new = speed;
- cpufreq_freq_transition_begin(policy, &freqs);
-
pr_debug("Setting to FSB:%dMHz Mult:%d.%dx (%s)\n",
fsb, mult/10, mult%10, print_speed(speed/1000));
retry_loop:
@@ -385,12 +385,14 @@
goto retry_loop;
}
}
- /* Report true CPU frequency */
- cpufreq_freq_transition_end(policy, &freqs, 0);
- if (!bm_timeout)
+ if (!bm_timeout) {
printk(KERN_INFO PFX "Warning: Timeout while waiting for "
"idle PCI bus.\n");
+ return -EBUSY;
+ }
+
+ return 0;
}
/*
@@ -631,9 +633,10 @@
unsigned int i;
unsigned int dir = 0;
u8 vid, current_vid;
+ int retval = 0;
if (!can_scale_voltage)
- longhaul_setstate(policy, table_index);
+ retval = longhaul_setstate(policy, table_index);
else {
/* On test system voltage transitions exceeding single
* step up or down were turning motherboard off. Both
@@ -648,7 +651,7 @@
while (i != table_index) {
vid = (longhaul_table[i].driver_data >> 8) & 0x1f;
if (vid != current_vid) {
- longhaul_setstate(policy, i);
+ retval = longhaul_setstate(policy, i);
current_vid = vid;
msleep(200);
}
@@ -657,10 +660,11 @@
else
i--;
}
- longhaul_setstate(policy, table_index);
+ retval = longhaul_setstate(policy, table_index);
}
+
longhaul_index = table_index;
- return 0;
+ return retval;
}
@@ -968,7 +972,15 @@
for (i = 0; i < numscales; i++) {
if (mults[i] == maxmult) {
+ struct cpufreq_freqs freqs;
+
+ freqs.old = policy->cur;
+ freqs.new = longhaul_table[i].frequency;
+ freqs.flags = 0;
+
+ cpufreq_freq_transition_begin(policy, &freqs);
longhaul_setstate(policy, i);
+ cpufreq_freq_transition_end(policy, &freqs, 0);
break;
}
}