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Date: Mon, 9 May 2016 14:59:49 +0200
From: Tomeu Vizoso <tomeu.vizoso@...labora.com>
To: Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Sebastian Reichel <sre@...nel.org>,
Sameer Nanda <snanda@...omium.org>,
Javier Martinez Canillas <javier@....samsung.com>,
Lee Jones <lee.jones@...aro.org>,
Benson Leung <bleung@...omium.org>,
Enric Balletbò <enric.balletbo@...labora.co.uk>,
Vic Yang <victoryang@...omium.org>,
Stephen Boyd <sboyd@...eaurora.org>,
Vincent Palatin <vpalatin@...omium.org>,
Randall Spangler <rspangler@...omium.org>,
Todd Broch <tbroch@...omium.org>,
Gwendal Grignou <gwendal@...omium.org>,
Shawn Nematbakhsh <shawnn@...omium.org>,
Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v8 6/7] power: cros_usbpd-charger: Add EC-based USB PD
charger driver
On 26 April 2016 at 12:47, Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
> Hi Tomeu,
>
> Thanks for the patch, looks good, a few comments below.
>
>
> On 20/04/16 09:42, Tomeu Vizoso wrote:
>>
>> Hi Sebastian,
>>
>> is there any chance that you could review this patch?
>>
>> Thanks,
>>
>> Tomeu
>>
>> On 12 April 2016 at 14:32, Tomeu Vizoso <tomeu.vizoso@...labora.com>
>> wrote:
>>>
>>> +config CHARGER_CROS_USB_PD
>>> + tristate "Chrome OS EC based USB PD charger"
>>> + depends on MFD_CROS_EC
>>> + default y
>
>
> Guess you should not set default to yes here.
Ok.
>>> +static int get_ec_num_ports(struct charger_data *charger, int
>>> *num_ports)
>>> +{
>>> + struct device *dev = charger->dev;
>>> + struct ec_response_usb_pd_ports resp;
>>> + int ret;
>>> +
>>> + *num_ports = 0;
>>> + ret = ec_command(charger->ec_dev, 0, EC_CMD_USB_PD_PORTS, NULL,
>>> 0,
>>> + (uint8_t *)&resp, sizeof(resp));
>>> + if (ret < 0) {
>>> + dev_err(dev, "Unable to query PD ports (err:0x%x)\n",
>>> ret);
>>> + return ret;
>
>
> Generally you return -EINVAL instead of ret when ec_command fails, any
> reason why here is different?
No reason indeed, will be changing it.
>>> + snprintf(port->manufacturer, MANUFACTURER_MODEL_LENGTH, "%x",
>>> resp.vid);
>
>
> This looks a vendor id code, generally I saw this propietry show the
> manufacturer name.
Unfortunately the EC firmware gives us only the USB vendor and product IDs.
>>> +
>>> + dev_dbg(dev, "cros_usb_pd_charger_power_changed\n");
>
>
> nit: In my opinion this debug message is not needed and doesn't add any
> information. It only shows that the function is called. You can usethe
> kernel tracing tools for that.
Agreed.
>>> + case POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX:
>>> + /* TODO: send a TBD host command to the EC. */
>>> + val->intval = 0;
>
>
> If I'm not mistaken the function below sets the control limit max value, but
> here you always return a 0. This is confusing for me. Seems that this is not
> supported yet? So maybe is better remove the code related to this or store
> the value set in a variable meanwhile you're not able to ask the value to
> the EC.
Good point, I have chosen to return -ENODATA as that should make clear
to the user that we cannot really show what is being asked right now.
>>> + msecs = ktime_to_ms(tstamp);
>>> + do_div(msecs, MSEC_PER_SEC);
>>> + pr_info("PDLOG %d/%02d/%02d %02d:%02d:%02d.%03llu P%d %s\n",
>>> + rt.tm_year + 1900, rt.tm_mon + 1, rt.tm_mday,
>>> + rt.tm_hour, rt.tm_min, rt.tm_sec, msecs,
>>> + PD_LOG_PORT(r->size_port), buf);
>
>
> nit: Maybe is better use a debug print level here. How often is this called?
This has been mentioned before, and the reason is that it's very
useful when helping users determine if the type-c cable that they are
using is defective or not:
http://www.ibtimes.co.uk/googler-shows-how-test-compatibility-usb-c-cable-chromebook-pixel-2015-1527334
Shouldn't happen often at all.
>>> +static int cros_usb_pd_charger_probe(struct platform_device *pd)
>>> +{
>>> + struct device *dev = &pd->dev;
>>> + struct cros_ec_dev *ec_dev = dev_get_drvdata(pd->dev.parent);
>>> + struct cros_ec_device *ec_device;
>>> + struct charger_data *charger;
>>> + struct port_data *port;
>>> + struct power_supply_desc *psy_desc;
>>> + struct power_supply_config psy_cfg = {};
>>> + int i;
>>> + int ret = -EINVAL;
>>> +
>>> + dev_dbg(dev, "cros_usb_pd_charger_probe\n");
>
>
> nit: Remove? You can use kernel tracing tools to print functions calls.
Cool.
>>> + if (!ec_dev) {
>>> + WARN(1, "%s: No EC dev found\n", dev_name(dev));
>>> + return -EINVAL;
>>> + }
>>> +
>>> + ec_device = ec_dev->ec_dev;
>>> + if (!ec_device) {
>>> + WARN(1, "%s: No EC device found\n", dev_name(dev));
>>> + return -EINVAL;
>>> + }
>>> +
>>> + charger = devm_kzalloc(dev, sizeof(struct charger_data),
>>> + GFP_KERNEL);
>
>
> Alignement should match with parentheses.
Ok.
>>> + if (!charger)
>>> + return -ENOMEM;
>>> +
>>> + charger->dev = dev;
>>> + charger->ec_dev = ec_dev;
>>> + charger->ec_device = ec_device;
>>> +
>>> + platform_set_drvdata(pd, charger);
>>> +
>>> + if ((get_ec_num_ports(charger, &charger->num_charger_ports) < 0)
>>> ||
>>> + !charger->num_charger_ports) {
>>> + dev_err(dev, "No charging ports found\n");
>>> + ret = -ENODEV;
>>> + goto fail;
>
>
> I think you can return -ENODEV directly here, you don't need to jump to
> fail.
The idea is to undo the call to platform_set_drvdata.
>>> + }
>>> +
>>> + for (i = 0; i < charger->num_charger_ports; i++) {
>>> + port = devm_kzalloc(dev, sizeof(struct port_data),
>>> GFP_KERNEL);
>>> + if (!port) {
>>> + ret = -ENOMEM;
>>> + goto fail;
>>> + }
>>> +
>>> + port->charger = charger;
>>> + port->port_number = i;
>>> + sprintf(port->name, CHARGER_DIR_NAME, i);
>>> +
>>> + psy_desc = &port->psy_desc;
>>> + psy_desc->name = port->name;
>>> + psy_desc->type = POWER_SUPPLY_TYPE_USB;
>>> + psy_desc->get_property = cros_usb_pd_charger_get_prop;
>>> + psy_desc->set_property = cros_usb_pd_charger_set_prop;
>>> + psy_desc->property_is_writeable =
>>> + cros_usb_pd_charger_is_writeable;
>>> + psy_desc->external_power_changed =
>>> + cros_usb_pd_charger_power_changed;
>>> + psy_desc->properties = cros_usb_pd_charger_props;
>>> + psy_desc->num_properties = ARRAY_SIZE(
>>> + cros_usb_pd_charger_props);
>>> +
>>> + psy_cfg.drv_data = port;
>>> + psy_cfg.supplied_to = charger_supplied_to;
>>> + psy_cfg.num_supplicants =
>>> ARRAY_SIZE(charger_supplied_to);
>>> +
>>> + port->psy = power_supply_register_no_ws(dev, psy_desc,
>>> + &psy_cfg);
>
>
> Guess you can use devm_power_supply_register_no_ws here.
Cool.
>>> + if (IS_ERR(port->psy)) {
>>> + dev_err(dev, "Failed to register power supply:
>>> %ld\n",
>>> + PTR_ERR(port->psy));
>>> + continue;
>>> + }
>>> +
>>> + charger->ports[charger->num_registered_psy++] = port;
>>> + }
>>> +
>>> + if (!charger->num_registered_psy) {
>>> + ret = -ENODEV;
>>> + dev_err(dev, "No power supplies registered\n");
>>> + goto fail;
>>> + }
>>> +
>>> + if (ec_device->mkbp_event_supported) {
>>> + /* Get PD events from the EC */
>>> + charger->notifier.notifier_call = cros_usb_pd_ec_event;
>>> + ret = blocking_notifier_chain_register(
>>> + &ec_device->event_notifier, &charger->notifier);
>>> + if (ret < 0)
>>> + dev_warn(dev, "failed to register notifier\n");
>>> + }
>>> +
>>> + /* Retrieve PD event logs periodically */
>>> + INIT_DELAYED_WORK(&charger->log_work, cros_usb_pd_log_check);
>>> + charger->log_workqueue =
>>> + create_singlethread_workqueue("cros_usb_pd_log");
>>> + queue_delayed_work(charger->log_workqueue, &charger->log_work,
>>> + CROS_USB_PD_LOG_UPDATE_DELAY);
>>> +
>>> + return 0;
>>> +
>>> +fail:
>>> + for (i = 0; i < charger->num_registered_psy; i++) {
>>> + port = charger->ports[i];
>>> + power_supply_unregister(port->psy);
>
>
> If you use devm_power_supply_register_no_ws this is not needed since it
> would be called by managed resources infrastructure.
Nod.
>>> + devm_kfree(dev, port);
>
>
> Guess the managed resources infrastructure will do this for you.
Nod.
> Best regards,
> Enric
Thanks a lot for the review!
Tomeu
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