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Date: Thu, 30 Jun 2016 19:01:06 +0800
From: Baolin Wang <baolin.wang@...aro.org>
To: Felipe Balbi <balbi@...nel.org>
Cc: Greg KH <gregkh@...uxfoundation.org>,
Sebastian Reichel <sre@...nel.org>,
Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
David Woodhouse <dwmw2@...radead.org>, robh@...nel.org,
Jun Li <jun.li@....com>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Ruslan Bilovol <ruslan.bilovol@...il.com>,
Peter Chen <peter.chen@...escale.com>,
Alan Stern <stern@...land.harvard.edu>, r.baldyga@...sung.com,
grygorii.strashko@...com,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
Lee Jones <lee.jones@...aro.org>,
Mark Brown <broonie@...nel.org>,
Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
patches@...nsource.wolfsonmicro.com,
Linux PM list <linux-pm@...r.kernel.org>,
USB <linux-usb@...r.kernel.org>,
device-mainlining@...ts.linuxfoundation.org,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v14 1/4] usb: gadget: Introduce the usb charger framework
Hi Felipe,
On 30 June 2016 at 18:30, Felipe Balbi <balbi@...nel.org> wrote:
>
> Hi,
>
> Baolin Wang <baolin.wang@...aro.org> writes:
>> +static ssize_t charger_state_show(struct device *dev,
>> + struct device_attribute *attr,
>> + char *buf)
>> +{
>> + struct usb_charger *uchger = dev_to_uchger(dev);
>> + int cnt;
>> +
>> + switch (uchger->state) {
>> + case USB_CHARGER_PRESENT:
>> + cnt = sprintf(buf, "%s\n", "PRESENT");
>> + break;
>> + case USB_CHARGER_REMOVE:
>> + cnt = sprintf(buf, "%s\n", "REMOVE");
>> + break;
>> + default:
>> + cnt = sprintf(buf, "%s\n", "UNKNOWN");
>> + break;
>
> are these the only states we need? Don't we need at least "CHARGING" and
> "ERROR" or something like that? Maybe those are exposed elsewhere,
> dunno.
Present state means we are charging. For charging error, I think it
can be exposed in power driver, which is more proper. Until now I only
see PRESENT and REMOVE state are useful.
>
>> +static int __usb_charger_set_cur_limit_by_type(struct usb_charger *uchger,
>> + enum usb_charger_type type,
>> + unsigned int cur_limit)
>> +{
>> + if (WARN(!uchger, "charger can not be NULL"))
>> + return -EINVAL;
>
> IIRC, I mentioned that this should assume charger to be a valid
> pointer. Look at this, for a second:
>
> You check that you have a valid pointer here...
Okay. I will remove this.
>
>> +int usb_charger_set_cur_limit_by_type(struct usb_charger *uchger,
>> + enum usb_charger_type type,
>> + unsigned int cur_limit)
>> +{
>> + int ret;
>> +
>> + if (WARN(!uchger, "charger can not be NULL"))
>> + return -EINVAL;
>
> ... and here, before calling the other function. This is the only place
> which should check for valid uchger.
Okay.
>
>> + mutex_lock(&uchger->lock);
>> + ret = __usb_charger_set_cur_limit_by_type(uchger, type, cur_limit);
>> + mutex_unlock(&uchger->lock);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(usb_charger_set_cur_limit_by_type);
>> +
>> +/*
>> + * usb_charger_set_cur_limit() - Set the current limitation.
>> + * @uchger - the usb charger instance.
>> + * @cur_limit_set - the current limitation.
>> + */
>> +int usb_charger_set_cur_limit(struct usb_charger *uchger,
>> + struct usb_charger_cur_limit *cur_limit_set)
>> +{
>> + if (WARN(!uchger || !cur_limit_set, "charger or setting can't be NULL"))
>> + return -EINVAL;
>
> I can see a pattern here. Not *all* errors need a splat. Sometimes a
> simple pr_err() or dev_err() (when you have a valid dev pointer) are
> enough.
Make sense.
>
>> diff --git a/include/linux/usb/charger.h b/include/linux/usb/charger.h
>> new file mode 100644
>> index 0000000..d2e745e
>> --- /dev/null
>> +++ b/include/linux/usb/charger.h
>> @@ -0,0 +1,164 @@
>> +#ifndef __LINUX_USB_CHARGER_H__
>> +#define __LINUX_USB_CHARGER_H__
>> +
>> +#include <uapi/linux/usb/ch9.h>
>> +#include <uapi/linux/usb/charger.h>
>> +
>> +#define CHARGER_NAME_MAX 30
>> +
>> +/* Current limitation by charger type */
>> +struct usb_charger_cur_limit {
>> + unsigned int sdp_cur_limit;
>> + unsigned int dcp_cur_limit;
>> + unsigned int cdp_cur_limit;
>> + unsigned int aca_cur_limit;
>> +};
>> +
>> +struct usb_charger_nb {
>> + struct notifier_block nb;
>> + struct usb_charger *uchger;
>> +};
>> +
>
> please add KernelDoc here. And mention the fields which aren't supposed
> to be accessed directly but should rely on the accessor functions. At
> least type and state prefer to be accessed by their respective
> getter/setter methods.
Will add kernel doc for struct usb_charger. Thanks for your comments.
>
>> +struct usb_charger {
>> + char name[CHARGER_NAME_MAX];
>> + struct list_head list;
>> + struct raw_notifier_head uchger_nh;
>> + /* protect the notifier head and charger */
>> + struct mutex lock;
>> + int id;
>> + enum usb_charger_type type;
>> + enum usb_charger_state state;
>> +
>> + /* for supporting extcon usb gpio */
>> + struct extcon_dev *extcon_dev;
>> + struct usb_charger_nb extcon_nb;
>> +
>> + /* for supporting usb gadget */
>> + struct usb_gadget *gadget;
>> + enum usb_device_state old_gadget_state;
>> +
>> + /* for supporting power supply */
>> + struct power_supply *psy;
>> +
>> + /* user can get charger type by implementing this callback */
>> + enum usb_charger_type (*get_charger_type)(struct usb_charger *);
>> + /*
>> + * charger detection method can be implemented if you need to
>> + * manually detect the charger type.
>> + */
>> + enum usb_charger_type (*charger_detect)(struct usb_charger *);
>> +
>> + /* current limitation */
>> + struct usb_charger_cur_limit cur_limit;
>> + /* to check if it is needed to change the SDP charger default current */
>> + unsigned int sdp_default_cur_change;
>> +};
>
> --
> balbi
--
Baolin.wang
Best Regards
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