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SubjectRe: [PATCH v3 3/3] power: wm831x_power: Support USB charger current limit management
Hi,

On Tue, Jul 25, 2017 at 04:00:01PM +0800, Baolin Wang wrote:
> Integrate with the newly added USB charger interface to limit the current
> we draw from the USB input based on the input device configuration
> identified by the USB stack, allowing us to charge more quickly from high
> current inputs without drawing more current than specified from others.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> Documentation/devicetree/bindings/mfd/wm831x.txt | 1 +
> drivers/power/supply/wm831x_power.c | 58 ++++++++++++++++++++++
> 2 files changed, 59 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mfd/wm831x.txt b/Documentation/devicetree/bindings/mfd/wm831x.txt
> index 9f8b743..4e3bc07 100644
> --- a/Documentation/devicetree/bindings/mfd/wm831x.txt
> +++ b/Documentation/devicetree/bindings/mfd/wm831x.txt
> @@ -31,6 +31,7 @@ Required properties:
> ../interrupt-controller/interrupts.txt
>
> Optional sub-nodes:
> + - usb-phy : Contains a phandle to the USB PHY.
> - regulators : Contains sub-nodes for each of the regulators supplied by
> the device. The regulators are bound using their names listed below:
>
> diff --git a/drivers/power/supply/wm831x_power.c b/drivers/power/supply/wm831x_power.c
> index 7082301..d3948ab 100644
> --- a/drivers/power/supply/wm831x_power.c
> +++ b/drivers/power/supply/wm831x_power.c
> @@ -13,6 +13,7 @@
> #include <linux/platform_device.h>
> #include <linux/power_supply.h>
> #include <linux/slab.h>
> +#include <linux/usb/phy.h>
>
> #include <linux/mfd/wm831x/core.h>
> #include <linux/mfd/wm831x/auxadc.h>
> @@ -31,6 +32,8 @@ struct wm831x_power {
> char usb_name[20];
> char battery_name[20];
> bool have_battery;
> + struct usb_phy *usb_phy;
> + struct notifier_block usb_notify;
> };
>
> static int wm831x_power_check_online(struct wm831x *wm831x, int supply,
> @@ -125,6 +128,43 @@ static int wm831x_usb_get_prop(struct power_supply *psy,
> POWER_SUPPLY_PROP_VOLTAGE_NOW,
> };
>
> +/* In milliamps */
> +static const unsigned int wm831x_usb_limits[] = {
> + 0,
> + 2,
> + 100,
> + 500,
> + 900,
> + 1500,
> + 1800,
> + 550,
> +};
> +
> +static int wm831x_usb_limit_change(struct notifier_block *nb,
> + unsigned long limit, void *data)
> +{
> + struct wm831x_power *wm831x_power = container_of(nb,
> + struct wm831x_power,
> + usb_notify);
> + unsigned int i, best;
> +
> + /* Find the highest supported limit */
> + best = 0;
> + for (i = 0; i < ARRAY_SIZE(wm831x_usb_limits); i++) {
> + if (limit >= wm831x_usb_limits[i] &&
> + wm831x_usb_limits[best] < wm831x_usb_limits[i])
> + best = i;
> + }
> +
> + dev_dbg(wm831x_power->wm831x->dev,
> + "Limiting USB current to %umA", wm831x_usb_limits[best]);
> +
> + wm831x_set_bits(wm831x_power->wm831x, WM831X_POWER_STATE,
> + WM831X_USB_ILIM_MASK, best);
> +
> + return 0;
> +}
> +
> /*********************************************************************
> * Battery properties
> *********************************************************************/
> @@ -607,6 +647,19 @@ static int wm831x_power_probe(struct platform_device *pdev)
> }
> }
>
> + power->usb_phy = devm_usb_get_phy_by_phandle(&pdev->dev,
> + "usb-phy", 0);
> + if (!IS_ERR(power->usb_phy)) {
> + power->usb_notify.notifier_call = wm831x_usb_limit_change;
> + ret = usb_register_notifier(power->usb_phy,
> + &power->usb_notify);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to register notifier: %d\n",
> + ret);
> + goto err_bat_irq;
> + }
> + }

No error handling for power->usb_phy? I think you should bail out
for all errors except for "not defined in DT". Especially I would
expect probe defer handling in case the power supply driver is
loaded before the phy driver.

> return ret;
>
> err_bat_irq:
> @@ -637,6 +690,11 @@ static int wm831x_power_remove(struct platform_device *pdev)
> struct wm831x *wm831x = wm831x_power->wm831x;
> int irq, i;
>
> + if (!IS_ERR(wm831x_power->usb_phy)) {
> + usb_unregister_notifier(wm831x_power->usb_phy,
> + &wm831x_power->usb_notify);
> + }
> +
> for (i = 0; i < ARRAY_SIZE(wm831x_bat_irqs); i++) {
> irq = wm831x_irq(wm831x,
> platform_get_irq_byname(pdev,

-- Sebastian
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