Hi Moritz,

	Please find my response inline.

-----Original Message-----
From: Moritz Fischer <mdf@kernel.org>
Sent: Saturday, April 10, 2021 3:01 AM
To: Nava kishore Manne <redacted>
Cc: mdf@kernel.org; trix@redhat.com; robh+dt@kernel.org; Michal Simek
[off-list ref]; linux-fpga@vger.kernel.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux-arm-
kernel@lists.infradead.org; git [off-list ref]
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:

quoted

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 <redacted>
---
 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,

quoted

 	}

 	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,

quoted

 					      struct of_overlay_notify_data

*nd)  {

quoted

+	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)

quoted

 		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.

Regards,
Navakishore.

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel