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: <20201024142907.GB26150@paasikivi.fi.intel.com>
Date:   Sat, 24 Oct 2020 17:29:07 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Dan Scally <djrscally@...il.com>,
        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

On Sat, Oct 24, 2020 at 03:39:55AM +0300, Laurent Pinchart wrote:
> Hi Sakari
> 
> On Wed, Oct 21, 2020 at 01:49:10AM +0300, Sakari Ailus wrote:
> > On Tue, Oct 20, 2020 at 08:56:07PM +0100, Dan Scally wrote:
> > > On 20/10/2020 13:06, Sakari Ailus wrote:
> > > > 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?
> > 
> > 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.
> 
> How about the following ?

Looks good to me.

> 
> diff --git a/drivers/base/property.c b/drivers/base/property.c
> index 81bd01ed4042..ea44ba846299 100644
> --- a/drivers/base/property.c
> +++ b/drivers/base/property.c
> @@ -706,9 +706,14 @@ EXPORT_SYMBOL_GPL(fwnode_handle_put);
>  /**
>   * fwnode_device_is_available - check if a device is available for use
>   * @fwnode: Pointer to the fwnode of the device.
> + *
> + * For fwnode node types that don't implement the .device_is_available()
> + * operation, such as software nodes, this function returns true.
>   */
>  bool fwnode_device_is_available(const struct fwnode_handle *fwnode)
>  {
> +	if (!fwnode_has_op(fwnode, device_is_available))
> +		return true;
>  	return fwnode_call_bool_op(fwnode, device_is_available);
>  }
>  EXPORT_SYMBOL_GPL(fwnode_device_is_available);
> 

-- 
Sakari Ailus