cpufreq: speedstep-smi: enable interrupts when waiting

[linux-drm-fsl-dcu.git] / drivers / cpufreq / speedstep-smi.c

diff --git a/drivers/cpufreq/speedstep-smi.c b/drivers/cpufreq/speedstep-smi.c
index 5fc96d5d656bafc251293d753be52326257a6c0b..819229e824fb69dde06d44d8726d95b5697d29da 100644 (file)
--- a/drivers/cpufreq/speedstep-smi.c
+++ b/drivers/cpufreq/speedstep-smi.c
@@ -156,6 +156,7 @@ static void speedstep_set_state(unsigned int state)
                return;
 
        /* Disable IRQs */
+       preempt_disable();
        local_irq_save(flags);
 
        command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
@@ -166,9 +167,19 @@ static void speedstep_set_state(unsigned int state)
 
        do {
                if (retry) {
+                       /*
+                        * We need to enable interrupts, otherwise the blockage
+                        * won't resolve.
+                        *
+                        * We disable preemption so that other processes don't
+                        * run. If other processes were running, they could
+                        * submit more DMA requests, making the blockage worse.
+                        */
                        pr_debug("retry %u, previous result %u, waiting...\n",
                                        retry, result);
+                       local_irq_enable();
                        mdelay(retry * 50);
+                       local_irq_disable();
                }
                retry++;
                __asm__ __volatile__(
@@ -185,6 +196,7 @@ static void speedstep_set_state(unsigned int state)
 
        /* enable IRQs */
        local_irq_restore(flags);
+       preempt_enable();
 
        if (new_state == state)
                pr_debug("change to %u MHz succeeded after %u tries "