linux-kernel - Re: [PATCH 2/2] platform/chrome: typec: Register Type C switches

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Date:   Thu, 30 Apr 2020 01:20:48 +0200
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Prashant Malani <pmalani@...omium.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Tim Wawrzynczak <twawrzynczak@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Guenter Roeck <groeck@...omium.org>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 2/2] platform/chrome: typec: Register Type C switches

Hi Prashant,


On 30/4/20 1:02, Prashant Malani wrote:
> Hi Enric,
> 
> Thanks for your review. Kindly see inline:
> 
> On Wed, Apr 29, 2020 at 3:22 PM Enric Balletbo i Serra
> <enric.balletbo@...labora.com> wrote:
>>
>> Hi Prashant,
>>
>> Thank you for your patch.
>>
>> On 23/4/20 0:22, Prashant Malani wrote:
>>> Register Type C mux and switch handles, when provided via firmware
>>> bindings. These will allow the cros-ec-typec driver, and also alternate
>>> mode drivers to configure connected Muxes correctly, according to PD
>>> information retrieved from the Chrome OS EC.
>>>
>>> Signed-off-by: Prashant Malani <pmalani@...omium.org>
>>> ---
>>>  drivers/platform/chrome/cros_ec_typec.c | 47 +++++++++++++++++++++++++
>>>  1 file changed, 47 insertions(+)
>>>
>>> diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
>>> index eda57db26f8d..324ead297c4d 100644
>>> --- a/drivers/platform/chrome/cros_ec_typec.c
>>> +++ b/drivers/platform/chrome/cros_ec_typec.c
>>> @@ -14,6 +14,8 @@
>>>  #include <linux/platform_data/cros_usbpd_notify.h>
>>>  #include <linux/platform_device.h>
>>>  #include <linux/usb/typec.h>
>>> +#include <linux/usb/typec_mux.h>
>>> +#include <linux/usb/role.h>
>>>
>>>  #define DRV_NAME "cros-ec-typec"
>>>
>>> @@ -25,6 +27,9 @@ struct cros_typec_port {
>>>       struct typec_partner *partner;
>>>       /* Port partner PD identity info. */
>>>       struct usb_pd_identity p_identity;
>>> +     struct typec_switch *ori_sw;
>>> +     struct typec_mux *mux;
>>> +     struct usb_role_switch *role_sw;
>>>  };
>>>
>>>  /* Platform-specific data for the Chrome OS EC Type C controller. */
>>> @@ -84,6 +89,40 @@ static int cros_typec_parse_port_props(struct typec_capability *cap,
>>>       return 0;
>>>  }
>>>
>>> +static int cros_typec_get_switch_handles(struct cros_typec_port *port,
>>> +                                      struct fwnode_handle *fwnode,
>>> +                                      struct device *dev)
>>> +{
>>> +     port->mux = fwnode_typec_mux_get(fwnode, NULL);
>>> +     if (IS_ERR(port->mux)) {
>>
>> Should you return an error if NULL is returned (IS_ERR_OR_NULL) ? I think that
>> fwnode_typec_mux_get can return NULL too.
> I think returning NULL can be considered "not an error" for devices
> that don't have kernel-controlled muxes (which won't have this
> property defined).
> So this check should be fine as is.
>>
>>
>>> +             dev_info(dev, "Mux handle not found.\n");
>>> +             goto mux_err;
>>> +     }
>>> +
>>> +     port->ori_sw = fwnode_typec_switch_get(fwnode);
>>> +     if (IS_ERR(port->ori_sw)) {
>>
>> ditto
>>
>>> +             dev_info(dev, "Orientation switch handle not found.\n");
>>> +             goto ori_sw_err;
>>> +     }
>>> +
>>> +     port->role_sw = fwnode_usb_role_switch_get(fwnode);
>>> +     if (IS_ERR(port->role_sw)) {
>>
>> ditto
>>
>>> +             dev_info(dev, "USB role switch handle not found.\n");
>>> +             goto role_sw_err;
>>> +     }
>>> +
>>> +     return 0;
>>> +
>>> +role_sw_err:
>>> +     usb_role_switch_put(port->role_sw);

I see, and put checks for NULL, so it's fine. Thanks for the clarification.

>>> +ori_sw_err:
>>> +     typec_switch_put(port->ori_sw);
>>> +mux_err:
>>> +     typec_mux_put(port->mux);
>>> +
>>> +     return -ENODEV;
>>> +}
>>> +
>>>  static void cros_unregister_ports(struct cros_typec_data *typec)
>>>  {
>>>       int i;
>>> @@ -91,6 +130,9 @@ static void cros_unregister_ports(struct cros_typec_data *typec)
>>>       for (i = 0; i < typec->num_ports; i++) {
>>>               if (!typec->ports[i])
>>>                       continue;
>>> +             usb_role_switch_put(typec->ports[i]->role_sw);
>>> +             typec_switch_put(typec->ports[i]->ori_sw);
>>> +             typec_mux_put(typec->ports[i]->mux);
>>>               typec_unregister_port(typec->ports[i]->port);
>>>       }
>>>  }
>>> @@ -153,6 +195,11 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
>>>                       ret = PTR_ERR(cros_port->port);
>>>                       goto unregister_ports;
>>>               }
>>> +
>>> +             ret = cros_typec_get_switch_handles(cros_port, fwnode, dev);
>>> +             if (ret)
>>> +                     dev_info(dev, "No switch control for port %d\n",
>>> +                              port_num);
>>
>> When drivers are working, they should not spit out any messages, make
>> this dev_dbg() at the most. Be quiet, please.
> Ack. Will update this in the next version.
>>
>>
>>>       }
>>>
>>>       return 0;
>>>