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From: Guenter Roeck <linux@roeck-us.net>
To: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>, linux-usb@vger.kernel.org
Subject: Re: [PATCH 1/7] usb: typec: Copy everything from struct typec_capability during registration
Date: Wed, 2 Oct 2019 20:45:28 -0700
Message-ID: <318179e6-fa1e-0b33-4a4f-40ecd6947f8a@roeck-us.net> (raw)
In-Reply-To: <20191002182933.GA19870@kuha.fi.intel.com>

On 10/2/19 11:29 AM, Heikki Krogerus wrote:
> On Wed, Oct 02, 2019 at 09:36:39AM -0700, Guenter Roeck wrote:
>> port->cap->type used to be the role provided by the low level driver.
>> That was static, and it was not possible to override it. It did not
>> resemble the current port type, or a configured port type, it resembled
>> port capabilities.
>>
>> Your code changes that, meaning even if the low level driver (effectively
>> the hardware) states that it can not support DRP, it is now configurable
>> anyway. That seems to me like a substantial change to the original meaning
>> of this attribute.
>>
>> Effectiv ely there are now three values,
>> - port->port_type	the current port tyle
>> - port->fixed_type	the type selected by the user
>> - port->cap->type	the type provided by low level code,
>> 			now no longer available / used
>>
>> Even if the low level driver (hardware) says that it can not support
>> TYPEC_PORT_DRP, that can be overwritten by the user. Maybe there is a
>> good reason for that, but I don't see it, sorry.
> 
> No, that was not my intention. Clearly there is a bug in my code.
> 
>> Maybe it would make sense to introduce port->fixed_type in a separate patch.
>> As part of that patch you could explain why port->cap->type, ie a reflection
>> of the port capabilities, is no longer needed.
> 
> Or, I could make this really simple. I could just copy the content of
> the cap as is to another struct typec_capability during port
> registration. My goal is really just remove the need for the device
> drivers keep the struct typec_capability instance if they don't need
> it, and I don't need to remove the cap member to achieve that.
> 

Maybe just use devm_kmemdup() ?

Guenter

> Nevertheless, IMO this attribute file really needs to be deprecated.
> On top of making things unnecessarily complicated for the userspace,
> it's making it difficult to make changes to the rest of the class
> code. We may not be able to get rid of the file, but there is nothing
> preventing us from supplying a better solution as an option.
> 

  reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01  9:48 [PATCH 0/7] usb: typec: Small API improvement Heikki Krogerus
2019-10-01  9:48 ` [PATCH 1/7] usb: typec: Copy everything from struct typec_capability during registration Heikki Krogerus
2019-10-01 13:08   ` Guenter Roeck
2019-10-02 16:06     ` Heikki Krogerus
2019-10-02 16:36       ` Guenter Roeck
2019-10-02 18:29         ` Heikki Krogerus
2019-10-03  3:45           ` Guenter Roeck [this message]
2019-10-03  8:03             ` Heikki Krogerus
2019-10-02 19:16       ` Heikki Krogerus
2019-10-03  3:51         ` Guenter Roeck
2019-10-03 13:29           ` Heikki Krogerus
2019-10-01  9:48 ` [PATCH 2/7] usb: typec: Introduce typec_get_drvdata() Heikki Krogerus
2019-10-01  9:48 ` [PATCH 3/7] usb: typec: Separate the operations vector Heikki Krogerus
2019-10-01 13:22   ` Guenter Roeck
2019-10-04  8:45     ` Heikki Krogerus
2019-10-01  9:48 ` [PATCH 4/7] usb: typec: tcpm: Start using struct typec_operations Heikki Krogerus
2019-10-01 13:30   ` Guenter Roeck
2019-10-04  8:46     ` Heikki Krogerus
2019-10-01  9:48 ` [PATCH 5/7] usb: typec: tps6598x: " Heikki Krogerus
2019-10-01 13:34   ` Guenter Roeck
2019-10-01 13:35   ` Guenter Roeck
2019-10-04  8:49     ` Heikki Krogerus
2019-10-01  9:48 ` [PATCH 6/7] usb: typec: ucsi: " Heikki Krogerus
2019-10-01 13:35   ` Guenter Roeck
2019-10-01  9:48 ` [PATCH 7/7] usb: typec: Remove the callback members from struct typec_capability Heikki Krogerus
2019-10-01 13:37   ` Guenter Roeck

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