Re: [RFC PATCH] Soundwire: Initialize multi_link with fwnode props

[Khalid Masum]

On 8/14/22 15:45, Greg KH wrote:
> On Sun, Aug 14, 2022 at 02:04:15PM +0600, Khalid Masum wrote:
> > According to the TODO, In sw_bus_master_add, bus->multi_link is to be
> > populated with properties from FW node props. Make this happen by
> > creating a new fwnode_handle flag FWNODE_FLAG_MULTI_LINKED and use
> > the flag to store the multi_link value from intel_link_startup. Use
> > this flag to initialize bus->multi_link.
> >
> > Signed-off-by: Khalid Masum <khalid.masum.92@xxxxxxxxx>
> > ---
> > I do not think adding a new flag for fwnode_handle is a good idea.
> > So, what would be the best way to initialize bus->multilink with
> > fwnode props?
> >
> >    -- Khalid Masum
> >
> >   drivers/soundwire/bus.c   | 4 ++--
> >   drivers/soundwire/intel.c | 1 +
> >   include/linux/fwnode.h    | 1 +
> >   3 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> > index a2bfb0434a67..80df1672c60b 100644
> > --- a/drivers/soundwire/bus.c
> > +++ b/drivers/soundwire/bus.c
> > @@ -74,9 +74,9 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
> >   
> >   	/*
> >   	 * Initialize multi_link flag
> > -	 * TODO: populate this flag by reading property from FW node
> >   	 */
> > -	bus->multi_link = false;
> > +	bus->multi_link = (fwnode->flags & FWNODE_FLAG_MULTI_LINKED)
> > +		== FWNODE_FLAG_MULTI_LINKED;
> >   	if (bus->ops->read_prop) {
> >   		ret = bus->ops->read_prop(bus);
> >   		if (ret < 0) {
> > diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
> > index 505c5ef061e3..034d1c523ddf 100644
> > --- a/drivers/soundwire/intel.c
> > +++ b/drivers/soundwire/intel.c
> > @@ -1347,6 +1347,7 @@ int intel_link_startup(struct auxiliary_device *auxdev)
> >   		 */
> >   		bus->multi_link = true;
> >   		bus->hw_sync_min_links = 1;
> > +		dev->fwnode->flags |= FWNODE_FLAG_MULTI_LINKED;
> >   	}
> >   
> >   	/* Initialize shim, controller */
> > diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
> > index 9a81c4410b9f..446a52744953 100644
> > --- a/include/linux/fwnode.h
> > +++ b/include/linux/fwnode.h
> > @@ -32,6 +32,7 @@ struct device;
> >   #define FWNODE_FLAG_NOT_DEVICE			BIT(1)
> >   #define FWNODE_FLAG_INITIALIZED			BIT(2)
> >   #define FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD	BIT(3)
> > +#define FWNODE_FLAG_MULTI_LINKED		BIT(4)
>
> What does this commit actually change?

The new flag will lets us save if the device has multilink in 
fwnode_handle whenever needed.
Then for soundwire/intel, save the multi_link flag into fwnode during 
startup.
Later at master_add, as written in todo, initialize the multilink flag 
with fwnode's flag property.

> Did you test this on real hardware?

I did not test this on real hardware.
> thanks,
>
> greg k-h

thanks,
 -- Khalid Masum