linux-kernel - Re: [PATCH v2 2/2] usb: typec: fusb302: add support of supported_pd

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Date:   Wed, 9 Feb 2022 11:34:23 +0800
From:   Potin Lai <potin.lai@...ntatw.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Patrick Williams <patrick@...cx.xyz>
Subject: Re: [PATCH v2 2/2] usb: typec: fusb302: add support of
 supported_pd_rev


Guenter Roeck 於 2022/2/8 下午 11:22 寫道:
> On 2/8/22 03:22, Potin Lai wrote:
>> Add support for passing supported PD rev to TCPM.
>> If "supported-pd-rev" property exist, then return supported_pd_rev as
>> defined value in DTS, otherwise return PD_MAX_REV
>>
>> Example of DTS:
>>
>> fusb302: typec-portc@22 {
>>      compatible = "fcs,fusb302";
>>      reg = <0x22>;
>>      ...
>>      supported-pd-rev=<1>; // PD_REV20
>>      ...
>> };
>>
>
> The new property needs to be documented. However, I am not entirely sure
> I understand why it is needed. Wouldn't the supported PD revision
> be a chip (fusb302) specific constant ? If so, why does it need a
> devicetree property ? I think that needs some additional explanation.
>
> Thanks,
> Guenter
>

My initially intend was adding flexibility for developer to decided 
which PD revision
they want to use for negotiation.

I saw your reply in another patch,  I agree with you, it will be simple 
and consistent if
move "supported-pd-rev" to tcpm fwnode as other capabilities.

Just want to double confirm, is "usb-connector.yaml" right place to put 
documentation
if adding "supported-pd-rev" in fwnode?

Thanks,
Potin

>> Signed-off-by: Potin Lai <potin.lai@...ntatw.com>
>> ---
>>   drivers/usb/typec/tcpm/fusb302.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/usb/typec/tcpm/fusb302.c 
>> b/drivers/usb/typec/tcpm/fusb302.c
>> index 72f9001b0792..8cff92d58b96 100644
>> --- a/drivers/usb/typec/tcpm/fusb302.c
>> +++ b/drivers/usb/typec/tcpm/fusb302.c
>> @@ -109,6 +109,9 @@ struct fusb302_chip {
>>       enum typec_cc_status cc2;
>>       u32 snk_pdo[PDO_MAX_OBJECTS];
>>   +    /* supported pd rev */
>> +    u32 supported_pd_rev;
>> +
>>   #ifdef CONFIG_DEBUG_FS
>>       struct dentry *dentry;
>>       /* lock for log buffer access */
>> @@ -1056,6 +1059,13 @@ static int tcpm_pd_transmit(struct tcpc_dev 
>> *dev, enum tcpm_transmit_type type,
>>       return ret;
>>   }
>>   +static u32 tcpm_supported_pd_rev(struct tcpc_dev *dev)
>> +{
>> +    struct fusb302_chip *chip = container_of(dev, struct fusb302_chip,
>> +                         tcpc_dev);
>> +    return chip->supported_pd_rev;
>> +}
>> +
>>   static enum typec_cc_status fusb302_bc_lvl_to_cc(u8 bc_lvl)
>>   {
>>       if (bc_lvl == FUSB_REG_STATUS0_BC_LVL_1230_MAX)
>> @@ -1129,6 +1139,7 @@ static void init_tcpc_dev(struct tcpc_dev 
>> *fusb302_tcpc_dev)
>>       fusb302_tcpc_dev->set_roles = tcpm_set_roles;
>>       fusb302_tcpc_dev->start_toggling = tcpm_start_toggling;
>>       fusb302_tcpc_dev->pd_transmit = tcpm_pd_transmit;
>> +    fusb302_tcpc_dev->supported_pd_rev = tcpm_supported_pd_rev;
>>   }
>>     static const char * const cc_polarity_name[] = {
>> @@ -1683,6 +1694,7 @@ static int fusb302_probe(struct i2c_client 
>> *client,
>>       struct fusb302_chip *chip;
>>       struct i2c_adapter *adapter = client->adapter;
>>       struct device *dev = &client->dev;
>> +    struct device_node *np = dev->of_node;
>>       const char *name;
>>       int ret = 0;
>>   @@ -1756,6 +1768,14 @@ static int fusb302_probe(struct i2c_client 
>> *client,
>>           dev_err(dev, "cannot request IRQ for GPIO Int_N, ret=%d", 
>> ret);
>>           goto tcpm_unregister_port;
>>       }
>> +
>> +    if (of_property_read_u32(np, "supported-pd-rev",
>> +                &chip->supported_pd_rev) < 0) {
>> +        chip->supported_pd_rev = PD_MAX_REV;
>> +    } else if (chip->supported_pd_rev > PD_MAX_REV) {
>> +        chip->supported_pd_rev = PD_MAX_REV;
>> +    }
>
> The else part is also checked in the tcpm code and thus seems
> to be redundant.
>
>> +
>>       enable_irq_wake(chip->gpio_int_n_irq);
>>       i2c_set_clientdata(client, chip);
>