linux-kernel - RE: [PATCH v3 4/4] bus: fsl-mc: add bus rescan attribute

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Date:   Mon, 2 Apr 2018 13:46:13 +0000
From:   Ioana Ciornei <ioana.ciornei@....com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     Laurentiu Tudor <laurentiu.tudor@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stuyoder@...il.com" <stuyoder@...il.com>,
        Ruxandra Ioana Ciocoi Radulescu <ruxandra.radulescu@....com>,
        "arnd@...db.de" <arnd@...db.de>,
        Razvan Stefanescu <razvan.stefanescu@....com>,
        Roy Pledge <roy.pledge@....com>
Subject: RE: [PATCH v3 4/4] bus: fsl-mc: add bus rescan attribute

> > Introduce the rescan attribute as a bus attribute to synchronize the
> > fsl-mc bus objects and the MC firmware.
> >
> > To rescan the fsl-mc bus, e.g.,
> > echo 1 > /sys/bus/fsl-mc/rescan
> >
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>
> > ---
> > Changes in v2:
> >   - added proper documentation in /Documentation/ABI/
> >   - updated the MAINTAINERS file
> > Changes in v3:
> >   - no change
> >
> >  Documentation/ABI/stable/sysfs-bus-fsl-mc |  7 +++++
> >  drivers/bus/fsl-mc/fsl-mc-bus.c           | 48
> +++++++++++++++++++++++++++++++
> >  2 files changed, 55 insertions(+)
> >
> > diff --git a/Documentation/ABI/stable/sysfs-bus-fsl-mc
> > b/Documentation/ABI/stable/sysfs-bus-fsl-mc
> > index e530e8c..0663fbd 100644
> > --- a/Documentation/ABI/stable/sysfs-bus-fsl-mc
> > +++ b/Documentation/ABI/stable/sysfs-bus-fsl-mc
> > @@ -4,3 +4,10 @@ KernelVersion:	4.16
> >  Contact:	Ioana Ciornei <ioana.ciornei@....com>
> >  Description:	Root dprc rescan attribute
> >  Users:		Userspace drivers and management tools
> > +
> > +What:		/sys/bus/fsl-mc/rescan
> > +Date:		March. 2018
> > +KernelVersion:	4.16
> 
> Same comments as previous review.
> 
> > +Contact:	Ioana Ciornei <ioana.ciornei@....com>
> > +Description:	Bus rescan attribute
> 
> Again, describe this better please.
> 
> > +Users:		Userspace drivers and management tools
> > diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c
> > b/drivers/bus/fsl-mc/fsl-mc-bus.c index 9d02984..80010d1 100644
> > --- a/drivers/bus/fsl-mc/fsl-mc-bus.c
> > +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
> > @@ -172,11 +172,59 @@ static ssize_t rescan_store(struct device *dev,
> >
> >  ATTRIBUTE_GROUPS(fsl_mc_dev);
> >
> > +static int scan_fsl_mc_bus(struct device *dev, void *data) {
> > +	struct fsl_mc_device *root_mc_dev;
> > +	struct fsl_mc_bus *root_mc_bus;
> > +
> > +	if (!fsl_mc_is_root_dprc(dev))
> > +		goto exit;
> > +
> > +	root_mc_dev = to_fsl_mc_device(dev);
> > +	root_mc_bus = to_fsl_mc_bus(root_mc_dev);
> > +	mutex_lock(&root_mc_bus->scan_mutex);
> > +	dprc_scan_objects(root_mc_dev, NULL);
> > +	mutex_unlock(&root_mc_bus->scan_mutex);
> > +
> > +exit:
> > +	return 0;
> > +}
> > +
> > +static ssize_t bus_rescan_store(struct bus_type *bus,
> > +				const char *buf, size_t count)
> > +{
> > +	unsigned long val;
> > +
> > +	if (kstrtoul(buf, 0, &val) < 0)
> > +		return -EINVAL;
> > +
> > +	if (val)
> > +		bus_for_each_dev(bus, NULL, NULL, scan_fsl_mc_bus);
> > +
> > +	return count;
> > +}
> > +static BUS_ATTR(rescan, 0220, NULL, bus_rescan_store);
> 
> BUS_ATTR_RO()?
> 
> 

Since this is a write-only attribute, a BUS_ATTR_WO would be needed but there is no WO macro defined.

Ioana

> 
> > +
> > +static struct attribute *fsl_mc_bus_attrs[] = {
> > +	&bus_attr_rescan.attr,
> > +	NULL,
> > +};
> > +
> > +static const struct attribute_group fsl_mc_bus_group = {
> > +	.attrs = fsl_mc_bus_attrs,
> > +};
> > +
> > +static const struct attribute_group *fsl_mc_bus_groups[] = {
> > +	&fsl_mc_bus_group,
> > +	NULL,
> > +};
> 
> ATTRIBUTE_GROUPS()?
> 
> thanks,
> 
> greg k-h