Re: [PATCH v3 3/3] power: wm831x_power: Support USB charger current limit management

[Baolin Wang]

Hi,

On 26 July 2017 at 20:08, Sebastian Reichel
<sebastian.reichel@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx> 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@xxxxxxxxxx>
>> >> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
>> >> ---
>> >>  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