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: <20201024165506.GB3943@pendragon.ideasonboard.com>
Date:   Sat, 24 Oct 2020 19:55:06 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Dan Scally <djrscally@...il.com>
Cc:     Sakari Ailus <sakari.ailus@...ux.intel.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

Hi Dan,

On Sat, Oct 24, 2020 at 05:33:32PM +0100, Dan Scally wrote:
> On 24/10/2020 15:29, Sakari Ailus wrote:
> > On Sat, Oct 24, 2020 at 03:39:55AM +0300, Laurent Pinchart wrote:
> >> 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.
>
> If we're agreed on this (and it's fine by me too), do you want me to
> include it in the next set, or are you going to do it separately Laurent?

Feel free to include it in the next version, but I can send a patch if
you prefer.

> >> 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);

-- 
Regards,

Laurent Pinchart