Re: [PATCH] power: supply: axp288-charger: Optimize register reading method

From: Sebastian Reichel
Date: Tue Oct 12 2021 - 11:12:07 EST

Hi,

On Tue, Oct 12, 2021 at 09:52:52AM +0200, Hans de Goede wrote:
> On 10/12/21 7:45 AM, Kate Hsuan wrote:
> > The original implementation access the charger the same register value
> > several times to get the charger status, such as online, enabled, and
> > bus limits. It takes a long time and bandwidth for every "status get"
> > operation. 
> >
> > To reduce the access of the register and save bandwidth, this commit
> > integrated every read operation into only one "register value get" 
> > operation and cache them in the variables. Once the "get properties"
> > is requested from the user space, the cached information can be returned
> > immediately.
> >
> > I2C access between Linux kernel and P-Unit is improved by explicitly taking
> > semaphore once for the entire set of register accesses in the new
> > axp288_charger_usb_update_property() function. The I2C-Bus to the XPower
> > AXP288 is shared between the Linux kernel and SoCs P-Unit. The P-Unit
> > has a semaphore which the kernel must "lock" before it may use the bus.
> > If not explicitly taken by the I2C-Driver, then this semaphore is
> > automatically taken by the I2C-bus-driver for each I2C-transfer. In
> > other words, the semaphore will be locked and released several times for
> > entire set of register accesses.
> >
> > Signed-off-by: Kate Hsuan <hpa@xxxxxxxxxx>
>
> Thanks, patch looks good to me:
>
> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>
> I've also given this a test run on a device with an AXP288 PMIC:
>
> Tested-by: Hans de Goede <hdegoede@xxxxxxxxxx>

Thanks, queued.

-- Sebastian

>
> Regards,
>
> Hans
>
> > ---
> > drivers/power/supply/axp288_charger.c | 150 +++++++++++++++++---------
> > 1 file changed, 99 insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/power/supply/axp288_charger.c b/drivers/power/supply/axp288_charger.c
> > index b9553be9bed5..fd4983c98fd9 100644
> > --- a/drivers/power/supply/axp288_charger.c
> > +++ b/drivers/power/supply/axp288_charger.c
> > @@ -22,6 +22,7 @@
> > #include <linux/mfd/axp20x.h>
> > #include <linux/extcon.h>
> > #include <linux/dmi.h>
> > +#include <asm/iosf_mbi.h>
> >
> > #define PS_STAT_VBUS_TRIGGER BIT(0)
> > #define PS_STAT_BAT_CHRG_DIR BIT(2)
> > @@ -95,6 +96,8 @@
> > #define CV_4200MV 4200 /* 4200mV */
> > #define CV_4350MV 4350 /* 4350mV */
> >
> > +#define AXP288_REG_UPDATE_INTERVAL (60 * HZ)
> > +
> > #define AXP288_EXTCON_DEV_NAME "axp288_extcon"
> > #define USB_HOST_EXTCON_HID "INT3496"
> > #define USB_HOST_EXTCON_NAME "INT3496:00"
> > @@ -118,6 +121,7 @@ struct axp288_chrg_info {
> > struct regmap_irq_chip_data *regmap_irqc;
> > int irq[CHRG_INTR_END];
> > struct power_supply *psy_usb;
> > + struct mutex lock;
> >
> > /* OTG/Host mode */
> > struct {
> > @@ -138,6 +142,12 @@ struct axp288_chrg_info {
> > int cv;
> > int max_cc;
> > int max_cv;
> > +
> > + unsigned long last_updated;
> > + unsigned int input_status;
> > + unsigned int op_mode;
> > + unsigned int backend_control;
> > + bool valid;
> > };
> >
> > static inline int axp288_charger_set_cc(struct axp288_chrg_info *info, int cc)
> > @@ -197,11 +207,8 @@ static inline int axp288_charger_set_cv(struct axp288_chrg_info *info, int cv)
> > static int axp288_charger_get_vbus_inlmt(struct axp288_chrg_info *info)
> > {
> > unsigned int val;
> > - int ret;
> >
> > - ret = regmap_read(info->regmap, AXP20X_CHRG_BAK_CTRL, &val);
> > - if (ret < 0)
> > - return ret;
> > + val = info->backend_control;
> >
> > val >>= CHRG_VBUS_ILIM_BIT_POS;
> > switch (val) {
> > @@ -297,55 +304,34 @@ static int axp288_charger_enable_charger(struct axp288_chrg_info *info,
> >
> > static int axp288_charger_is_present(struct axp288_chrg_info *info)
> > {
> > - int ret, present = 0;
> > - unsigned int val;
> > -
> > - ret = regmap_read(info->regmap, AXP20X_PWR_INPUT_STATUS, &val);
> > - if (ret < 0)
> > - return ret;
> > + int present = 0;
> >
> > - if (val & PS_STAT_VBUS_PRESENT)
> > + if (info->input_status & PS_STAT_VBUS_PRESENT)
> > present = 1;
> > return present;
> > }
> >
> > static int axp288_charger_is_online(struct axp288_chrg_info *info)
> > {
> > - int ret, online = 0;
> > - unsigned int val;
> > -
> > - ret = regmap_read(info->regmap, AXP20X_PWR_INPUT_STATUS, &val);
> > - if (ret < 0)
> > - return ret;
> > + int online = 0;
> >
> > - if (val & PS_STAT_VBUS_VALID)
> > + if (info->input_status & PS_STAT_VBUS_VALID)
> > online = 1;
> > return online;
> > }
> >
> > static int axp288_get_charger_health(struct axp288_chrg_info *info)
> > {
> > - int ret, pwr_stat, chrg_stat;
> > int health = POWER_SUPPLY_HEALTH_UNKNOWN;
> > - unsigned int val;
> >
> > - ret = regmap_read(info->regmap, AXP20X_PWR_INPUT_STATUS, &val);
> > - if ((ret < 0) || !(val & PS_STAT_VBUS_PRESENT))
> > + if (!(info->input_status & PS_STAT_VBUS_PRESENT))
> > goto health_read_fail;
> > - else
> > - pwr_stat = val;
> >
> > - ret = regmap_read(info->regmap, AXP20X_PWR_OP_MODE, &val);
> > - if (ret < 0)
> > - goto health_read_fail;
> > - else
> > - chrg_stat = val;
> > -
> > - if (!(pwr_stat & PS_STAT_VBUS_VALID))
> > + if (!(info->input_status & PS_STAT_VBUS_VALID))
> > health = POWER_SUPPLY_HEALTH_DEAD;
> > - else if (chrg_stat & CHRG_STAT_PMIC_OTP)
> > + else if (info->op_mode & CHRG_STAT_PMIC_OTP)
> > health = POWER_SUPPLY_HEALTH_OVERHEAT;
> > - else if (chrg_stat & CHRG_STAT_BAT_SAFE_MODE)
> > + else if (info->op_mode & CHRG_STAT_BAT_SAFE_MODE)
> > health = POWER_SUPPLY_HEALTH_SAFETY_TIMER_EXPIRE;
> > else
> > health = POWER_SUPPLY_HEALTH_GOOD;
> > @@ -362,30 +348,86 @@ static int axp288_charger_usb_set_property(struct power_supply *psy,
> > int ret = 0;
> > int scaled_val;
> >
> > + mutex_lock(&info->lock);
> > switch (psp) {
> > case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> > scaled_val = min(val->intval, info->max_cc);
> > scaled_val = DIV_ROUND_CLOSEST(scaled_val, 1000);
> > ret = axp288_charger_set_cc(info, scaled_val);
> > - if (ret < 0)
> > + if (ret < 0) {
> > dev_warn(&info->pdev->dev, "set charge current failed\n");
> > + goto out;
> > + }
> > break;
> > case POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE:
> > scaled_val = min(val->intval, info->max_cv);
> > scaled_val = DIV_ROUND_CLOSEST(scaled_val, 1000);
> > ret = axp288_charger_set_cv(info, scaled_val);
> > - if (ret < 0)
> > + if (ret < 0) {
> > dev_warn(&info->pdev->dev, "set charge voltage failed\n");
> > + goto out;
> > + }
> > break;
> > case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> > ret = axp288_charger_set_vbus_inlmt(info, val->intval);
> > - if (ret < 0)
> > + if (ret < 0) {
> > dev_warn(&info->pdev->dev, "set input current limit failed\n");
> > + goto out;
> > + }
> > + info->valid = false;
> > break;
> > default:
> > ret = -EINVAL;
> > }
> >
> > +out:
> > + mutex_unlock(&info->lock);
> > + return ret;
> > +}
> > +
> > +static int axp288_charger_reg_readb(struct axp288_chrg_info *info, int reg, unsigned int *ret_val)
> > +{
> > + int ret;
> > +
> > + ret = regmap_read(info->regmap, reg, ret_val);
> > + if (ret < 0) {
> > + dev_err(&info->pdev->dev, "Error %d on reading value from register 0x%04x\n",
> > + ret,
> > + reg);
> > + return ret;
> > + }
> > + return 0;
> > +}
> > +
> > +static int axp288_charger_usb_update_property(struct axp288_chrg_info *info)
> > +{
> > + int ret = 0;
> > +
> > + if (info->valid && time_before(jiffies, info->last_updated + AXP288_REG_UPDATE_INTERVAL))
> > + return 0;
> > +
> > + dev_dbg(&info->pdev->dev, "Charger updating register values...\n");
> > +
> > + ret = iosf_mbi_block_punit_i2c_access();
> > + if (ret < 0)
> > + return ret;
> > +
> > + ret = axp288_charger_reg_readb(info, AXP20X_PWR_INPUT_STATUS, &info->input_status);
> > + if (ret < 0)
> > + goto out;
> > +
> > + ret = axp288_charger_reg_readb(info, AXP20X_PWR_OP_MODE, &info->op_mode);
> > + if (ret < 0)
> > + goto out;
> > +
> > + ret = axp288_charger_reg_readb(info, AXP20X_CHRG_BAK_CTRL, &info->backend_control);
> > + if (ret < 0)
> > + goto out;
> > +
> > + info->last_updated = jiffies;
> > + info->valid = true;
> > +out:
> > + iosf_mbi_unblock_punit_i2c_access();
> > return ret;
> > }
> >
> > @@ -396,6 +438,11 @@ static int axp288_charger_usb_get_property(struct power_supply *psy,
> > struct axp288_chrg_info *info = power_supply_get_drvdata(psy);
> > int ret;
> >
> > + mutex_lock(&info->lock);
> > + ret = axp288_charger_usb_update_property(info);
> > + if (ret < 0)
> > + goto out;
> > +
> > switch (psp) {
> > case POWER_SUPPLY_PROP_PRESENT:
> > /* Check for OTG case first */
> > @@ -403,10 +450,7 @@ static int axp288_charger_usb_get_property(struct power_supply *psy,
> > val->intval = 0;
> > break;
> > }
> > - ret = axp288_charger_is_present(info);
> > - if (ret < 0)
> > - return ret;
> > - val->intval = ret;
> > + val->intval = axp288_charger_is_present(info);
> > break;
> > case POWER_SUPPLY_PROP_ONLINE:
> > /* Check for OTG case first */
> > @@ -414,10 +458,7 @@ static int axp288_charger_usb_get_property(struct power_supply *psy,
> > val->intval = 0;
> > break;
> > }
> > - ret = axp288_charger_is_online(info);
> > - if (ret < 0)
> > - return ret;
> > - val->intval = ret;
> > + val->intval = axp288_charger_is_online(info);
> > break;
> > case POWER_SUPPLY_PROP_HEALTH:
> > val->intval = axp288_get_charger_health(info);
> > @@ -435,16 +476,15 @@ static int axp288_charger_usb_get_property(struct power_supply *psy,
> > val->intval = info->max_cv * 1000;
> > break;
> > case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> > - ret = axp288_charger_get_vbus_inlmt(info);
> > - if (ret < 0)
> > - return ret;
> > - val->intval = ret;
> > + val->intval = axp288_charger_get_vbus_inlmt(info);
> > break;
> > default:
> > - return -EINVAL;
> > + ret = -EINVAL;
> > }
> >
> > - return 0;
> > +out:
> > + mutex_unlock(&info->lock);
> > + return ret;
> > }
> >
> > static int axp288_charger_property_is_writeable(struct power_supply *psy,
> > @@ -540,7 +580,9 @@ static irqreturn_t axp288_charger_irq_thread_handler(int irq, void *dev)
> > dev_warn(&info->pdev->dev, "Spurious Interrupt!!!\n");
> > goto out;
> > }
> > -
> > + mutex_lock(&info->lock);
> > + info->valid = false;
> > + mutex_unlock(&info->lock);
> > power_supply_changed(info->psy_usb);
> > out:
> > return IRQ_HANDLED;
> > @@ -613,6 +655,9 @@ static void axp288_charger_extcon_evt_worker(struct work_struct *work)
> > if (!(val & PS_STAT_VBUS_VALID)) {
> > dev_dbg(&info->pdev->dev, "USB charger disconnected\n");
> > axp288_charger_enable_charger(info, false);
> > + mutex_lock(&info->lock);
> > + info->valid = false;
> > + mutex_unlock(&info->lock);
> > power_supply_changed(info->psy_usb);
> > return;
> > }
> > @@ -644,6 +689,9 @@ static void axp288_charger_extcon_evt_worker(struct work_struct *work)
> > dev_err(&info->pdev->dev,
> > "error setting current limit (%d)\n", ret);
> >
> > + mutex_lock(&info->lock);
> > + info->valid = false;
> > + mutex_unlock(&info->lock);
> > power_supply_changed(info->psy_usb);
> > }
> >
> >
>

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