Vishwanath BS <vishwanath.bs@xxxxxx> writes:
> This patch introduces an API to perform DVFS for a given voltage domain.
> It takes omap_vdd_dvfs_info pointer as input parameter, computes the highest
> requested voltage for that vdd and scales all the devices in that vdd to the
> requested frequency along with voltage scaling.
>
> Based on original patch from Thara.
>
> Signed-off-by: Vishwanath BS <vishwanath.bs@xxxxxx>
> Cc: Thara Gopinath <thara@xxxxxx>
> ---
> arch/arm/mach-omap2/dvfs.c | 87 +++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 86 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/dvfs.c b/arch/arm/mach-omap2/dvfs.c
> index 8832e4a..cefc2be 100755
> --- a/arch/arm/mach-omap2/dvfs.c
> +++ b/arch/arm/mach-omap2/dvfs.c
> @@ -21,7 +21,7 @@
> #include <plat/omap_device.h>
>
> /**
> - * struct omap_dev_user_list - Structure maitain userlist per devide
> + * struct omap_dev_user_list - Structure maitain userlist per device
this typo should be done in the original patch, not here.
> *
> * @dev: The device requesting for a particular frequency
> * @node: The list head entry
> @@ -413,6 +413,91 @@ static int omap_dvfs_remove_freq_request(struct omap_vdd_dvfs_info *dvfs_info,
> }
>
> /**
> + * omap_dvfs_voltage_scale() : API to scale the devices associated with a
> + * voltage domain vdd voltage.
This function scales both voltage and frequency, so the name
voltage_scale() is a bit misleading.
> + * @dvfs_info: omap_vdd_dvfs_info pointer for the required vdd
> + *
> + * This API runs through the list of devices associated with the
> + * voltage domain and scales the device rates to the one requested
> + * by the user or those corresponding to the new voltage of the
> + * voltage domain. Target voltage is the highest voltage in the vdd_user_list.
> + *
> + * Returns 0 on success
> + * else the error value.
> + */
> +static int omap_dvfs_voltage_scale(struct omap_vdd_dvfs_info *dvfs_info)
> +{
> + unsigned long curr_volt;
> + int is_volt_scaled = 0;
should be a bool
> + struct omap_vdd_dev_list *temp_dev;
> + struct plist_node *node;
> + int ret = 0;
> + struct voltagedomain *voltdm;
> + unsigned long volt;
> +
> + if (!dvfs_info || IS_ERR(dvfs_info)) {
> + pr_warning("%s: VDD specified does not exist!\n", __func__);
> + return -EINVAL;
> + }
> +
> + voltdm = dvfs_info->voltdm;
> +
> + mutex_lock(&dvfs_info->scaling_mutex);
> +
> + /* Find the highest voltage being requested */
> + node = plist_last(&dvfs_info->user_list);
> + volt = node->prio;
> +
> + curr_volt = omap_voltage_get_nom_volt(voltdm);
> +
> + if (curr_volt == volt) {
> + is_volt_scaled = 1;
> + } else if (curr_volt < volt) {
> + ret = omap_voltage_scale_vdd(voltdm, volt);
> + if (ret) {
> + pr_warning("%s: Unable to scale the %s to %ld volt\n",
> + __func__, voltdm->name, volt);
> + mutex_unlock(&dvfs_info->scaling_mutex);
> + return ret;
> + }
> + is_volt_scaled = 1;
> + }
> +
> + list_for_each_entry(temp_dev, &dvfs_info->dev_list, node) {
> + struct device *dev;
> + struct opp *opp;
> + unsigned long freq;
> +
> + dev = temp_dev->dev;
if you're doing this assignment here, might as well make 'dev' the
iterator instead of temp_dev.
This section would benefit with some comments. If I understand the code
correctly, something like:
If a frequency has been requested, use the highest requested frequency.
> + if (!plist_head_empty(&temp_dev->user_list)) {
> + node = plist_last(&temp_dev->user_list);
> + freq = node->prio;
otherwise check if device has OPP for this voltage
> + } else {
> + opp = omap_dvfs_find_voltage(dev, volt);
> + if (IS_ERR(opp))
> + continue;
This needs a comment to, but I'm not sure I understand what's going on
here. What it seems like:
if this device has no OPP for this voltage, just silently move on to the
next device? doesn't seem quite right, but not sure I fully grok the
failure modes of omap_dvfs_find_voltage()
Kevin
> + freq = opp_get_freq(opp);
> + }
> +
> + if (freq == omap_device_get_rate(dev)) {
> + dev_dbg(dev, "%s: Already at the requested"
> + "rate %ld\n", __func__, freq);
> + continue;
> + }
> +
> + ret |= omap_device_set_rate(dev, freq);
> + }
> +
> + if (!is_volt_scaled && !ret)
> + omap_voltage_scale_vdd(voltdm, volt);
> +
> + mutex_unlock(&dvfs_info->scaling_mutex);
> +
> + return 0;
> +}
> +
> +/**
> * omap_dvfs_init() - Initialize omap dvfs layer
> *
> * Initalizes omap dvfs layer. It basically allocates memory for
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