linux-kernel - Re: [RFC PATCH v3 7/9] ipu3-cio2: Check if pci_dev->dev's fwnode is a software_node in cio2_parse_firmware() and set FWNODE_GRAPH_DEVICE

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Message-ID: <6a77e6d8-45b4-e4d3-ad16-97a8573c8efc@gmail.com>
Date:   Tue, 20 Oct 2020 23:55:59 +0100
From:   Dan Scally <djrscally@...il.com>
To:     Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux.walleij@...aro.org, prabhakar.mahadev-lad.rj@...renesas.com,
        heikki.krogerus@...ux.intel.com, dmitry.torokhov@...il.com,
        laurent.pinchart+renesas@...asonboard.com,
        kieran.bingham+renesas@...asonboard.com, jacopo+renesas@...ndi.org,
        robh@...nel.org, davem@...emloft.net, linux@...musvillemoes.dk,
        sergey.senozhatsky@...il.com, rostedt@...dmis.org,
        pmladek@...e.com, mchehab@...nel.org, tian.shu.qiu@...el.com,
        bingbu.cao@...el.com, yong.zhi@...el.com, rafael@...nel.org,
        gregkh@...uxfoundation.org, kitakar@...il.com,
        dan.carpenter@...cle.org
Subject: Re: [RFC PATCH v3 7/9] ipu3-cio2: Check if pci_dev->dev's fwnode is a
 software_node in cio2_parse_firmware() and set FWNODE_GRAPH_DEVICE_DISABLED
 if so

Hi Sakari

On 20/10/2020 23:49, Sakari Ailus wrote:
> Hi Dan,
>
> On Tue, Oct 20, 2020 at 08:56:07PM +0100, Dan Scally wrote:
>> Hi Sakari
>>
>> On 20/10/2020 13:06, Sakari Ailus wrote:
>>> Hi Andy,
>>>
>>> On Tue, Oct 20, 2020 at 12:19:58PM +0300, Andy Shevchenko wrote:
>>>> On Mon, Oct 19, 2020 at 11:59:01PM +0100, Daniel Scally wrote:
>>>>> fwnode_graph_get_endpoint_by_id() will optionally parse enabled devices
>>>>> only; that status being determined through the .device_is_available() op
>>>>> of the device's fwnode. As software_nodes don't have that operation and
>>>>> adding it is meaningless, we instead need to check if the device's fwnode
>>>>> is a software_node and if so pass the appropriate flag to disable that
>>>>> check
>>>> Period.
>>>>
>>>> I'm wondering if actually this can be hidden in fwnode_graph_get_endpoint_by_id().
>>> The device availability test is actually there for a reason. Some firmware
>>> implementations put all the potential devices in the tables and only one
>>> (of some) of them are available.
>>>
>>> Could this be implemented so that if the node is a software node, then get
>>> its parent and then see if that is available?
>>>
>>> I guess that could be implemented in software node ops. Any opinions?
>> Actually when considering the cio2 device, it seems that
>> set_secondary_fwnode() actually overwrites the _primary_, given
>> fwnode_is_primary(dev->fwnode) returns false. So in at least some cases,
>> this wouldn't work.
> Ouch. I wonder when this happens --- have you checked what's the primary
> there? I guess it might be if it's a PCI device without the corresponding
> ACPI device node?
Yes; it's null, and I think that diagnosis is correct.
> I remember you had an is_available implementation that just returned true
> for software nodes in an early version of the set? I think it would still
> be a lesser bad in this case.
Yep - I can put that back in and just drop this patch then; fine for me.