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

[Khalid Masum]

On 8/15/22 12:37, Greg KH wrote:
> On Mon, Aug 15, 2022 at 10:08:07AM +0600, Khalid Masum wrote:
> > 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;
>
> I missed that this was an if statement here, please write this to be
> more obvious and readable.
>
> > > >    	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.
>
> And what does that allow to happen?  What changes with all of this?

As suggested by Pierre-Louis Bossart these changes are not necessary and 
the TODO is to be removed. Earlier my intention was to create a new flag 
that lets us know whether multi_link is to be read from 
sdw_bus_master_add just as instructed in TODO.

I shall send another patch, that removes the TODO, as suggested by 
Pierre-Louis Bossart.
> thanks,
>
> greg k-h

thanks,
  -- Khalid Masum