Re: [PATCH] thermal: of: look for sensor driver parent node if device node missing

[Laxman Dewangan]

On Wednesday 30 July 2014 06:48 PM, Eduardo Valentin wrote:
> Laxman,
>
> On Mon, Jul 14, 2014 at 02:04:55PM +0200, Lucas Stach wrote:
> > Am Montag, den 14.07.2014, 16:42 +0530 schrieb Laxman Dewangan:
> > > There are some mfd devices which supports junction thermal interrupt
> > > like ams,AS3722. The DT binding of these devices are defined as the
> > > flat and drivers for sub module of such devices are registered as
> > > the mfd_add_devices. In this method, the sub devices registered as
> > > platform driver and these do not have the of_node pointer on their
> > > device structure. In this case, use the parent of_node pointer to
> > > get the required of_node pointer.
> > >
> > > Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> > > ---
> > >   drivers/thermal/of-thermal.c | 2 ++
> > >   1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/thermal/of-thermal.c b/drivers/thermal/of-thermal.c
> > > index 04b1be7..85a7d71 100644
> > > --- a/drivers/thermal/of-thermal.c
> > > +++ b/drivers/thermal/of-thermal.c
> > > @@ -396,6 +396,8 @@ thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
> > >   		return ERR_PTR(-EINVAL);
> > >   
> > >   	sensor_np = dev->of_node;
> > > +	if (!sensor_np && dev->parent)
> > > +		sensor_np = dev->parent->of_node;
> > >   
> > >   	for_each_child_of_node(np, child) {
> > >   		struct of_phandle_args sensor_specs;
> > This seems like the wrong way around. If the MFD has subdev information
> > stored in the parent node it should be the MFD drivers responsibility to
> > populate the subdev of_node with its own node. The subdev should not be
> > forced to make such possible unsafe assumptions.
> This is my understanding too. MFD device drivers must populate the
> required data onto their sub devices while creating them.

Sometime ago, Stephen sent patch on MFD to initialize the mfd sub 
devices of_node with parent node.

mfd: always assign of_node in mfd_add_device()
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-December/217482.html

But it has unforeseen issue and reverted with patch
mfd: Revert "mfd: Always assign of_node in mfd_add_device()"
https://groups.google.com/forum/#!msg/rtc-linux/2LeLipSPFs0/XfPCKpT1BnUJ

So we do not have any mechanism here to pass the parent of_node to the 
of-thermal.

Adding Stephen and Lee for more comment.
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