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

On 26 July 2017 at 20:08, Sebastian Reichel
<sebastian.reichel@collabora.co.uk> wrote:
> Hi,
>
> On Wed, Jul 26, 2017 at 11:05:25AM +0800, Baolin Wang wrote:
>> On 25 July 2017 at 17:59, Sebastian Reichel
>> <sebastian.reichel@collabora.co.uk> wrote:
>> > 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.
>>
>> Make sense. So I think I need to change like below:
>>
>> 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;
>> }
>> } else if (PTR_ERR(power->usb_phy) != -ENODEV &&
>> PTR_ERR(power->usb_phy) != -EINVAL) {
>> ret = PTR_ERR(power->usb_phy);
>> dev_err(&pdev->dev, "Failed to find USB phy: %d\n", ret);
>> goto err_bat_irq;
>> }
>>
>> The return value -EINVAL means the platform device does not have a
>> device node and -ENODEV means we did not set the 'usb-phy' phandle,
>> other errors we should bail out including -PROBE_DEFER. Is it OK for
>> you?
>
> Yes, but I think the following is better, which avoids
> spamming the log with probe defer messages.
>
> power->usb_phy = devm_usb_get_phy_by_phandle(&pdev->dev, "usb-phy", 0);
> ret = PTR_ERR_OR_ZERO(power->usb_phy);
>
> switch (ret) {
> case 0:
> 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;
> }
> break;
> case -EINVAL:
> case -ENODEV:
> /* ignore missing usb-phy, it's optional */
> power->usb_phy = NULL;
> break;
> default:
> dev_err(&pdev->dev, "Failed to find USB phy: %d\n", ret);
> /* fall-through */
> case -EPROBE_DEFER:
> goto err_bat_irq;
> break;
> }

OK. Thanks.

--
Baolin.wang
Best Regards

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