Re: [PATCH v2] drm/panthor: Fix the CONFIG_PM=n case

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Il 18/03/24 16:31, Boris Brezillon ha scritto:
Putting a hard dependency on CONFIG_PM is not possible because of a
circular dependency issue, and it's actually not desirable either. In
order to support this use case, we forcibly resume at init time, and
suspend at unplug time.

v2:
- Drop the #ifdef CONFIG_PM section around panthor_pm_ops's definition

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202403031944.EOimQ8WK-lkp@xxxxxxxxx/
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>

---
Tested by faking CONFIG_PM=n in the driver (basically commenting
all pm_runtime calls, and making the panthor_device_suspend/resume()
calls unconditional in the panthor_device_unplug/init() path) since
CONFIG_ARCH_ROCKCHIP selects CONFIG_PM. Seems to work fine, but I
can't be 100% sure this will work correctly on a platform that has
CONFIG_PM=n.
---
  drivers/gpu/drm/panthor/panthor_device.c | 13 +++++++++++--
  drivers/gpu/drm/panthor/panthor_drv.c    |  2 +-
  2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 69deb8e17778..ba7aedbb4931 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -87,6 +87,10 @@ void panthor_device_unplug(struct panthor_device *ptdev)
  	pm_runtime_dont_use_autosuspend(ptdev->base.dev);
  	pm_runtime_put_sync_suspend(ptdev->base.dev);
+ /* If PM is disabled, we need to call the suspend handler manually. */
+	if (!IS_ENABLED(CONFIG_PM))
+		panthor_device_suspend(ptdev->base.dev);
+
  	/* Report the unplug operation as done to unblock concurrent
  	 * panthor_device_unplug() callers.
  	 */
@@ -218,6 +222,13 @@ int panthor_device_init(struct panthor_device *ptdev)
  	if (ret)
  		return ret;
+ /* If PM is disabled, we need to call panthor_device_resume() manually. */
+	if (!IS_ENABLED(CONFIG_PM)) {
+		ret = panthor_device_resume(ptdev->base.dev);
+		if (ret)
+			return ret;
+	}
+
  	ret = panthor_gpu_init(ptdev);
  	if (ret)
  		goto err_rpm_put;
@@ -402,7 +413,6 @@ int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *
  	return 0;
  }
-#ifdef CONFIG_PM
  int panthor_device_resume(struct device *dev)
  {
  	struct panthor_device *ptdev = dev_get_drvdata(dev);
@@ -547,4 +557,3 @@ int panthor_device_suspend(struct device *dev)
  	mutex_unlock(&ptdev->pm.mmio_lock);
  	return ret;
  }
-#endif
diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
index ff484506229f..11b3ccd58f85 100644
--- a/drivers/gpu/drm/panthor/panthor_drv.c
+++ b/drivers/gpu/drm/panthor/panthor_drv.c
@@ -1417,7 +1417,7 @@ static struct platform_driver panthor_driver = {
  	.remove_new = panthor_remove,
  	.driver = {
  		.name = "panthor",
-		.pm = &panthor_pm_ops,
+		.pm = pm_ptr(&panthor_pm_ops),
  		.of_match_table = dt_match,
  	},
  };




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