Re: [PATCH 3/3] fpga: region: Adds runtime PM support

[Tom Rix <trix@xxxxxxxxxx>]

On 6/2/21 3:48 AM, Nava kishore Manne wrote:
> Ping!
>
> > -----Original Message-----
> > From: Nava kishore Manne
> > Sent: Monday, April 19, 2021 10:49 AM
> > To: Moritz Fischer <mdf@xxxxxxxxxx>
> > Cc: trix@xxxxxxxxxx; robh+dt@xxxxxxxxxx; Michal Simek
> > <michals@xxxxxxxxxx>; linux-fpga@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> > kernel@xxxxxxxxxxxxxxxxxxx; git <git@xxxxxxxxxx>
> > Subject: RE: [PATCH 3/3] fpga: region: Adds runtime PM support
> >
> > Hi Moritz,
> >
> > 	Please find my response inline.
> >
> > > -----Original Message-----
> > > From: Moritz Fischer <mdf@xxxxxxxxxx>
> > > Sent: Saturday, April 10, 2021 3:01 AM
> > > To: Nava kishore Manne <navam@xxxxxxxxxx>
> > > Cc: mdf@xxxxxxxxxx; trix@xxxxxxxxxx; robh+dt@xxxxxxxxxx; Michal Simek
> > > <michals@xxxxxxxxxx>; linux-fpga@xxxxxxxxxxxxxxx;
> > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> > > kernel@xxxxxxxxxxxxxxxxxxx; git <git@xxxxxxxxxx>
> > > Subject: Re: [PATCH 3/3] fpga: region: Adds runtime PM support
> > >
> > > On Fri, Apr 02, 2021 at 02:50:49PM +0530, Nava kishore Manne wrote:
> > > > Adds support to handle FPGA/PL power domain. With this patch, the PL
> > > > power domain will be turned on before loading the bitstream and
> > > > turned off while removing/unloading the bitstream using overlays.
> > > > This can be achieved by adding the runtime PM support.
> > > >
> > > > Signed-off-by: Nava kishore Manne <nava.manne@xxxxxxxxxx>
> > > > ---
> > > >   drivers/fpga/of-fpga-region.c | 18 +++++++++++++++++-
> > > >   1 file changed, 17 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/fpga/of-fpga-region.c
> > > > b/drivers/fpga/of-fpga-region.c index e405309baadc..35fc2f3d4bd8
> > > > 100644
> > > > --- a/drivers/fpga/of-fpga-region.c
> > > > +++ b/drivers/fpga/of-fpga-region.c
> > > > @@ -15,6 +15,7 @@
> > > >   #include <linux/of_platform.h>
> > > >   #include <linux/slab.h>
> > > >   #include <linux/spinlock.h>
> > > > +#include <linux/pm_runtime.h>
> > > >
> > > >   static const struct of_device_id fpga_region_of_match[] = {
> > > >   	{ .compatible = "fpga-region", },
> > > > @@ -302,6 +303,7 @@ static int
> > > > of_fpga_region_notify_pre_apply(struct
> > > fpga_region *region,
> > > >   	}
> > > >
> > > >   	region->info = info;
> > > > +	pm_runtime_get_sync(dev->parent);
> > > >   	ret = fpga_region_program_fpga(region);
> > > >   	if (ret) {
> > > >   		/* error; reject overlay */
> > > > @@ -324,10 +326,13 @@ static int
> > > > of_fpga_region_notify_pre_apply(struct fpga_region *region,  static
> > > > void
> > > of_fpga_region_notify_post_remove(struct fpga_region *region,
> > > >   					      struct of_overlay_notify_data
> > > *nd)  {
> > > > +	struct device *dev = &region->dev;
> > > > +
> > > >   	fpga_bridges_disable(&region->bridge_list);
> > > >   	fpga_bridges_put(&region->bridge_list);
> > > >   	fpga_image_info_free(region->info);
> > > >   	region->info = NULL;
> > > > +	pm_runtime_put(dev->parent);
> > > >   }
> > > >
> > > >   /**
> > > > @@ -411,9 +416,16 @@ static int of_fpga_region_probe(struct
> > > platform_device *pdev)
> > > >   		goto eprobe_mgr_put;
> > > >   	}
> > > >
> > > > +	pm_runtime_enable(&pdev->dev);
> > > > +	ret = pm_runtime_get_sync(&pdev->dev);
> > > > +	if (ret < 0)
> > > > +		goto err_pm;
> > > > +
> > > > +	pm_runtime_put(&pdev->dev);
> > > > +
> > > >   	ret = fpga_region_register(region);
> > > >   	if (ret)
> > > > -		goto eprobe_mgr_put;
> > > > +		goto err_pm;
> > > >
> > > >   	of_platform_populate(np, fpga_region_of_match, NULL, &region-
> > > > dev);
> > > >   	platform_set_drvdata(pdev, region);  @@ -422,6 +434,9 @@ static
> > > > int of_fpga_region_probe(struct  platform_device *pdev)
> > > >
> > > >   	return 0;
> > > >
> > > > +err_pm:
> > > > +	pm_runtime_put(&pdev->dev);
> > > > +	pm_runtime_disable(&pdev->dev);
> > > >   eprobe_mgr_put:
> > > >   	fpga_mgr_put(mgr);
> > > >   	return ret;
> > > > @@ -434,6 +449,7 @@ static int of_fpga_region_remove(struct
> > > > platform_device *pdev)
> > > >
> > > >   	fpga_region_unregister(region);
> > > >   	fpga_mgr_put(mgr);
> > > > +	pm_runtime_disable(region->dev.parent);
> > > >
> > > >   	return 0;
> > > >   }
> > > > --
> > > > 2.18.0
> > > Does this add a dependency on CONFIG_PM?
> > Yes, the newly added functionality has a dependency on CONFIG_PM if it's
> > disabled the expected power domain (in our cases it's PL) will not powered
> > ON/OFF dynamically at runtime and this is as an expected behavior. Other
> > than this it will not impact the any of the driver existing functionality.

This looks like a general change for a specific board.

Why can't this be done at the board level ?

Tom

> > Regards,
> > Navakishore.