[PATCH 1/7] drm/amdgpu: add a dev_pm_ops prepare callback (v2)

[Quan, Evan]

[AMD Public Use]

Hi Alex,

By checking the document and source code of pci_pm_prepare(), it seems the prepare callback provided by device driver is optional, not must.
- even without the prepare callback provide by device driver, the ->prepare of subsystem/bus can still return positive number(1)
- the result of  the prepare callback provide by device driver may be not honored unless DPM_FLAG_SMART_PREPARE is set.

BR
Evan
-----Original Message-----
From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Alex Deucher
Sent: Tuesday, March 9, 2021 12:10 PM
To: amd-gfx at lists.freedesktop.org
Cc: Deucher, Alexander <Alexander.Deucher at amd.com>
Subject: [PATCH 1/7] drm/amdgpu: add a dev_pm_ops prepare callback (v2)

as per:
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel.org%2Fdoc%2Fhtml%2Flatest%2Fdriver-api%2Fpm%2Fdevices.html&data=04%7C01%7Cevan.quan%40amd.com%7C6e3b5c960f1145c79e1c08d8e2b14a95%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637508598383549752%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=hLOdKKeO7JMk5kU5gmYSrBD53LhsT8vtEH3UivKjx48%3D&reserved=0

The prepare callback is required to support the DPM_FLAG_SMART_SUSPEND driver flag.  This allows runtime pm to auto complete when the system goes into suspend avoiding a wake up on suspend and on resume.
Apply this for hybrid gfx and BOCO systems where d3cold is provided by the ACPI platform.

v2: check if device is runtime suspended in prepare.

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index aecf7baf219a..8d4fbee01011 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -36,6 +36,7 @@
 #include <linux/vga_switcheroo.h>
 #include <drm/drm_probe_helper.h>
 #include <linux/mmu_notifier.h>
+#include <linux/suspend.h>
 
 #include "amdgpu.h"
 #include "amdgpu_irq.h"
@@ -1293,6 +1294,27 @@ amdgpu_pci_shutdown(struct pci_dev *pdev)
 	adev->mp1_state = PP_MP1_STATE_NONE;
 }
 
+static int amdgpu_pmops_prepare(struct device *dev) {
+	struct drm_device *drm_dev = dev_get_drvdata(dev);
+
+	/* Return a positive number here so
+	 * DPM_FLAG_SMART_SUSPEND works properly
+	 */
+	if ((amdgpu_device_supports_atpx(drm_dev) &&
+	    amdgpu_is_atpx_hybrid()) ||
+	    amdgpu_device_supports_boco(drm_dev))
+		return pm_runtime_suspended(dev) &&
+			pm_suspend_via_firmware();
+
+	return 0;
+}
+
+static void amdgpu_pmops_complete(struct device *dev) {
+	/* nothing to do */
+}
+
 static int amdgpu_pmops_suspend(struct device *dev)  {
 	struct drm_device *drm_dev = dev_get_drvdata(dev); @@ -1511,6 +1533,8 @@ long amdgpu_drm_ioctl(struct file *filp,  }
 
 static const struct dev_pm_ops amdgpu_pm_ops = {
+	.prepare = amdgpu_pmops_prepare,
+	.complete = amdgpu_pmops_complete,
 	.suspend = amdgpu_pmops_suspend,
 	.resume = amdgpu_pmops_resume,
 	.freeze = amdgpu_pmops_freeze,
--
2.29.2

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