[Intel-gfx] [RFC 2/3] drm: Register drmfs filesystem from drm init

[sourab gupta]

On Thu, 2016-12-01 at 23:57 -0800, Daniel Vetter wrote:
> On Thu, Dec 01, 2016 at 01:44:16PM +0530, swati.dhingra at intel.com wrote:
> > From: Swati Dhingra <swati.dhingra at intel.com>
> > 
> > During drm module initialization, drm_core_init initializes the drmfs
> > filesystem and register this with kernel. A driver specific directory is created
> > inside drmfs root, and dentry of this directory is saved for subsequent use
> > by the driver (e.g. i915). The driver can then create files/directories inside
> > this root directory directly.
> > In case of i915 driver, the top directory is created at '/sys/kernel/drm/i915'.
> > 
> > Signed-off-by: Sourab Gupta <sourab.gupta at intel.com>
> > Signed-off-by: Swati Dhingra <swati.dhingra at intel.com>
> > ---
> >  drivers/gpu/drm/drm_drv.c | 22 ++++++++++++++++++++++
> >  include/drm/drm_drv.h     |  3 +++
> >  2 files changed, 25 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> > index 84fcfcb..ead360bd 100644
> > --- a/drivers/gpu/drm/drm_drv.c
> > +++ b/drivers/gpu/drm/drm_drv.c
> > @@ -688,6 +688,14 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
> >  {
> >  	int ret;
> >  
> > +#ifdef CONFIG_DRMFS
> > +	dev->driver->drmfs_root = drmfs_create_dir(dev->driver->name, NULL);
> > +	if (IS_ERR(dev->driver->drmfs_root)) {
> > +		DRM_ERROR("Failed to get drmfs root dentry\n");
> > +		return PTR_ERR(dev->driver->drmfs_root);
> > +	}
> > +#endif
> 
> Don't do #ifdef in the code, instead provide dummy static inline functions
> that do nothing in headers when a feature is disabled. For an example see
> CONFIG_DRM_FBDEV_EMULATION in drm_fb_helper.[hc].
> 
Sorry, Will take take of this going forward.

> Also, drmfs here is seriously lacking documentation. E.g. where are we
> supposed to put different things related to rendering, modesetting, and
> all these issues? You need to add a section in drm-uabi.rst, write
> kernel-doc + overview sections for all of this and pull it in.
> -Daniel
> 
Ok. Will work on adding requisite documentation for drmfs.

Thanks,
Sourab

> > +
> >  	mutex_lock(&drm_global_mutex);
> >  
> >  	ret = drm_minor_register(dev, DRM_MINOR_CONTROL);
> > @@ -758,6 +766,9 @@ void drm_dev_unregister(struct drm_device *dev)
> >  	drm_minor_unregister(dev, DRM_MINOR_PRIMARY);
> >  	drm_minor_unregister(dev, DRM_MINOR_RENDER);
> >  	drm_minor_unregister(dev, DRM_MINOR_CONTROL);
> > +#ifdef CONFIG_DRMFS
> > +	drmfs_remove(dev->driver->drmfs_root);
> > +#endif
> >  }
> >  EXPORT_SYMBOL(drm_dev_unregister);
> >  
> > @@ -825,6 +836,9 @@ static void drm_core_exit(void)
> >  {
> >  	unregister_chrdev(DRM_MAJOR, "drm");
> >  	debugfs_remove(drm_debugfs_root);
> > +#ifdef CONFIG_DRMFS
> > +	drmfs_fini();
> > +#endif
> >  	drm_sysfs_destroy();
> >  	idr_destroy(&drm_minors_idr);
> >  	drm_connector_ida_destroy();
> > @@ -845,6 +859,14 @@ static int __init drm_core_init(void)
> >  		goto error;
> >  	}
> >  
> > +#ifdef CONFIG_DRMFS
> > +	ret = drmfs_init();
> > +	if (ret < 0) {
> > +		DRM_ERROR("Cannot create DRM FS: %d\n", ret);
> > +		goto error;
> > +	}
> > +#endif
> > +
> >  	drm_debugfs_root = debugfs_create_dir("dri", NULL);
> >  	if (!drm_debugfs_root) {
> >  		ret = -ENOMEM;
> > diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> > index aad8bba..34804de 100644
> > --- a/include/drm/drm_drv.h
> > +++ b/include/drm/drm_drv.h
> > @@ -403,6 +403,9 @@ struct drm_driver {
> >  
> >  	/* List of devices hanging off this driver with stealth attach. */
> >  	struct list_head legacy_dev_list;
> > +
> > +	/* drmfs parent directory dentry for this driver */
> > +	struct dentry *drmfs_root;
> >  };
> >  
> >  extern __printf(6, 7)
> > -- 
> > 2.7.4
> > 
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>