Re: [alsa-devel] [PATCH 1/3 v4 RESEND] mfd: arizona: Export function to control subsystem DVFS

+int arizona_dvfs_down(struct arizona *arizona, unsigned int flags) +{

• int ret = 0;
• mutex_lock(&arizona->subsys_max_lock);
• if ((arizona->subsys_max_rq & flags) != flags)

• dev_warn(arizona->dev, "Unbalanced DVFS down: %x\n", flags);
  

This warning is bogus and should be removed. These are just simple on/off bit flags, not a reference count. If a requestor is already at the lower DVFS state we just do nothing.

It was done this way to keep the code simple and lower risk. None of the blocks that need to move the DVFS frequency up and down have multiple users so they are simple either/or cases that don't currently reference count themselves. So having a boolean flag to match the state of each block keeps the change set smaller.

• arizona->subsys_max_rq &= ~flags;
• if (arizona->subsys_max_rq == 0) {

• switch (arizona->type) {
  

• case WM5102:
  

• case WM8997:
  

• 	ret = regmap_update_bits(arizona->regmap,
  

• 			ARIZONA_DYNAMIC_FREQUENCY_SCALING_1,
  

• 			ARIZONA_SUBSYS_MAX_FREQ, 0);
  

• 	if (ret != 0)
  

• 		dev_err(arizona->dev,
  

• 			"Failed to disable subsys max: %d\n",
  

• 			ret);
  

• 	ret = regulator_set_voltage(arizona->dcvdd,
  

• 				    1200000, 1800000);
  

• 	if (ret != 0)
  

• 		dev_err(arizona->dev,
  

• 			"Failed to set DCVDD (DVFS down): %d\n",
  

• 			ret);
  

• 	break;
  

• default:
  

• 	break;
  

• }
  

• }
• mutex_unlock(&arizona->subsys_max_lock);
• return ret;

+} +EXPORT_SYMBOL_GPL(arizona_dvfs_down);