[PATCH v4 1/2] PCI: Add a helper to check Power Resource Requirements _PR3 existence

[PATCH v4 1/2] PCI: Add a helper to check Power Resource Requirements _PR3 existence

[Kai-Heng Feng]

A driver may want to know the existence of _PR3, to choose different
runtime suspend behavior. A user will be add in next patch.

This is mostly the same as nouveau_pr3_present().

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v4:
- Let caller to find its upstream port device.

 drivers/pci/pci.c   | 16 ++++++++++++++++
 include/linux/pci.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e7982af9a5d8..d03f624d8928 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5856,6 +5856,22 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
 	return 0;
 }
 
+bool pci_pr3_present(struct pci_dev *pdev)
+{
+	struct acpi_device *adev;
+
+	if (acpi_disabled)
+		return false;
+
+	adev = ACPI_COMPANION(&pdev->dev);
+	if (!adev)
+		return false;
+
+	return adev->power.flags.power_resources &&
+		acpi_has_method(adev->handle, "_PR3");
+}
+EXPORT_SYMBOL_GPL(pci_pr3_present);
+
 /**
  * pci_add_dma_alias - Add a DMA devfn alias for a device
  * @dev: the PCI device for which alias is added
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f9088c89a534..1d15c5d49cdd 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2310,9 +2310,11 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
 
 void
 pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
+bool pci_pr3_present(struct pci_dev *pdev);
 #else
 static inline struct irq_domain *
 pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
+static bool pci_pr3_present(struct pci_dev *pdev) { return false; }
 #endif
 
 #ifdef CONFIG_EEH
-- 
2.17.1

[PATCH v4 2/2] ALSA: hda: Allow HDA to be runtime suspended when dGPU is not bound to a driver

[Kai-Heng Feng]

Nvidia proprietary driver doesn't support runtime power management, so
when a user only wants to use the integrated GPU, it's a common practice
to let dGPU not to bind any driver, and let its upstream port to be
runtime suspended. At the end of runtime suspension the port uses
platform power management to disable power through _OFF method of power
resource, which is listed by _PR3.

After commit b516ea586d71 ("PCI: Enable NVIDIA HDA controllers"), when
the dGPU comes with an HDA function, the HDA won't be suspended if the
dGPU is unbound, so the power resource can't be turned off by its
upstream port driver.

Commit 37a3a98ef601 ("ALSA: hda - Enable runtime PM only for
discrete GPU") only allows HDA to be runtime suspended once GPU is
bound, to keep APU's HDA working.

However, HDA on dGPU isn't that useful if dGPU is not bound to any
driver.  So let's relax the runtime suspend requirement for dGPU's HDA
function, to disable the power source to save lots of power.

BugLink: https://bugs.launchpad.net/bugs/1840835
Fixes: b516ea586d71 ("PCI: Enable NVIDIA HDA controllers")
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v4:
- Find upstream port, it's callee's responsibility now.
v3:
- Make changelog more clear.
v2:
- Change wording.
- Rebase to Tiwai's branch.
 sound/pci/hda/hda_intel.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index 240f4ca76391..e63b871343e5 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -1280,11 +1280,17 @@ static void init_vga_switcheroo(struct azx *chip)
 {
 	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
 	struct pci_dev *p = get_bound_vga(chip->pci);
+	struct pci_dev *parent;
 	if (p) {
 		dev_info(chip->card->dev,
 			 "Handle vga_switcheroo audio client\n");
 		hda->use_vga_switcheroo = 1;
-		chip->bus.keep_power = 1; /* cleared in either gpu_bound op or codec probe */
+
+		/* cleared in either gpu_bound op or codec probe, or when its
+		 * upstream port has _PR3 (i.e. dGPU).
+		 */
+		parent = pci_upstream_bridge(p);
+		chip->bus.keep_power = parent ? !pci_pr3_present(parent) : 1;
 		chip->driver_caps |= AZX_DCAPS_PM_RUNTIME;
 		pci_dev_put(p);
 	}
-- 
2.17.1

[PATCH v5 1/2] PCI: Add pci_pr3_present() helper to check Power Resource for D3hot

[Kai-Heng Feng]

Add pci_pr3_present() to check whether the platform supplies _PR3 to
tell us which power resources the device depends on when in D3hot. This
information is useful to let drivers choose different runtime suspend
behavior. A user will be add in next patch.

This is mostly the same as nouveau_pr3_present().

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v5:
- Add wording suggestion from Bjorn.
v4:
- Let caller to find its upstream port device.

 drivers/pci/pci.c   | 16 ++++++++++++++++
 include/linux/pci.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e7982af9a5d8..d03f624d8928 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5856,6 +5856,22 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
 	return 0;
 }
 
+bool pci_pr3_present(struct pci_dev *pdev)
+{
+	struct acpi_device *adev;
+
+	if (acpi_disabled)
+		return false;
+
+	adev = ACPI_COMPANION(&pdev->dev);
+	if (!adev)
+		return false;
+
+	return adev->power.flags.power_resources &&
+		acpi_has_method(adev->handle, "_PR3");
+}
+EXPORT_SYMBOL_GPL(pci_pr3_present);
+
 /**
  * pci_add_dma_alias - Add a DMA devfn alias for a device
  * @dev: the PCI device for which alias is added
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f9088c89a534..1d15c5d49cdd 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2310,9 +2310,11 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
 
 void
 pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
+bool pci_pr3_present(struct pci_dev *pdev);
 #else
 static inline struct irq_domain *
 pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
+static bool pci_pr3_present(struct pci_dev *pdev) { return false; }
 #endif
 
 #ifdef CONFIG_EEH
-- 
2.17.1

Re: [PATCH v5 1/2] PCI: Add pci_pr3_present() helper to check Power Resource for D3hot

[Bjorn Helgaas]

On Wed, Sep 25, 2019 at 07:43:53PM +0800, Kai-Heng Feng wrote:
> Add pci_pr3_present() to check whether the platform supplies _PR3 to
> tell us which power resources the device depends on when in D3hot. This
> information is useful to let drivers choose different runtime suspend
> behavior. A user will be add in next patch.
> 
> This is mostly the same as nouveau_pr3_present().
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

I assume Takashi will merge this along with the ALSA patch.

> ---
> v5:
> - Add wording suggestion from Bjorn.
> v4:
> - Let caller to find its upstream port device.
> 
>  drivers/pci/pci.c   | 16 ++++++++++++++++
>  include/linux/pci.h |  2 ++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e7982af9a5d8..d03f624d8928 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5856,6 +5856,22 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
>  	return 0;
>  }
>  
> +bool pci_pr3_present(struct pci_dev *pdev)
> +{
> +	struct acpi_device *adev;
> +
> +	if (acpi_disabled)
> +		return false;
> +
> +	adev = ACPI_COMPANION(&pdev->dev);
> +	if (!adev)
> +		return false;
> +
> +	return adev->power.flags.power_resources &&
> +		acpi_has_method(adev->handle, "_PR3");
> +}
> +EXPORT_SYMBOL_GPL(pci_pr3_present);
> +
>  /**
>   * pci_add_dma_alias - Add a DMA devfn alias for a device
>   * @dev: the PCI device for which alias is added
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index f9088c89a534..1d15c5d49cdd 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -2310,9 +2310,11 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
>  
>  void
>  pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
> +bool pci_pr3_present(struct pci_dev *pdev);
>  #else
>  static inline struct irq_domain *
>  pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
> +static bool pci_pr3_present(struct pci_dev *pdev) { return false; }
>  #endif
>  
>  #ifdef CONFIG_EEH
> -- 
> 2.17.1
> 

Re: [PATCH v4 2/2] ALSA: hda: Allow HDA to be runtime suspended when dGPU is not bound to a driver

[Kai-Heng Feng]

Hi Takashi,

> On Sep 25, 2019, at 19:32, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> 
> Nvidia proprietary driver doesn't support runtime power management, so
> when a user only wants to use the integrated GPU, it's a common practice
> to let dGPU not to bind any driver, and let its upstream port to be
> runtime suspended. At the end of runtime suspension the port uses
> platform power management to disable power through _OFF method of power
> resource, which is listed by _PR3.
> 
> After commit b516ea586d71 ("PCI: Enable NVIDIA HDA controllers"), when
> the dGPU comes with an HDA function, the HDA won't be suspended if the
> dGPU is unbound, so the power resource can't be turned off by its
> upstream port driver.
> 
> Commit 37a3a98ef601 ("ALSA: hda - Enable runtime PM only for
> discrete GPU") only allows HDA to be runtime suspended once GPU is
> bound, to keep APU's HDA working.
> 
> However, HDA on dGPU isn't that useful if dGPU is not bound to any
> driver.  So let's relax the runtime suspend requirement for dGPU's HDA
> function, to disable the power source to save lots of power.
> 
> BugLink: https://bugs.launchpad.net/bugs/1840835
> Fixes: b516ea586d71 ("PCI: Enable NVIDIA HDA controllers")
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

Do you still have any concern on this patch?
Please merge [v5 1/2] and this patch [v4 2/2] if you think it's good.

Thanks!

Kai-Heng

> ---
> v4:
> - Find upstream port, it's callee's responsibility now.
> v3:
> - Make changelog more clear.
> v2:
> - Change wording.
> - Rebase to Tiwai's branch.
> sound/pci/hda/hda_intel.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 240f4ca76391..e63b871343e5 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -1280,11 +1280,17 @@ static void init_vga_switcheroo(struct azx *chip)
> {
> 	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
> 	struct pci_dev *p = get_bound_vga(chip->pci);
> +	struct pci_dev *parent;
> 	if (p) {
> 		dev_info(chip->card->dev,
> 			 "Handle vga_switcheroo audio client\n");
> 		hda->use_vga_switcheroo = 1;
> -		chip->bus.keep_power = 1; /* cleared in either gpu_bound op or codec probe */
> +
> +		/* cleared in either gpu_bound op or codec probe, or when its
> +		 * upstream port has _PR3 (i.e. dGPU).
> +		 */
> +		parent = pci_upstream_bridge(p);
> +		chip->bus.keep_power = parent ? !pci_pr3_present(parent) : 1;
> 		chip->driver_caps |= AZX_DCAPS_PM_RUNTIME;
> 		pci_dev_put(p);
> 	}
> -- 
> 2.17.1
> 

Re: [PATCH v4 2/2] ALSA: hda: Allow HDA to be runtime suspended when dGPU is not bound to a driver

[Takashi Iwai]

On Mon, 07 Oct 2019 20:49:56 +0200,
Kai-Heng Feng wrote:
> 
> Hi Takashi,
> 
> > On Sep 25, 2019, at 19:32, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> > 
> > Nvidia proprietary driver doesn't support runtime power management, so
> > when a user only wants to use the integrated GPU, it's a common practice
> > to let dGPU not to bind any driver, and let its upstream port to be
> > runtime suspended. At the end of runtime suspension the port uses
> > platform power management to disable power through _OFF method of power
> > resource, which is listed by _PR3.
> > 
> > After commit b516ea586d71 ("PCI: Enable NVIDIA HDA controllers"), when
> > the dGPU comes with an HDA function, the HDA won't be suspended if the
> > dGPU is unbound, so the power resource can't be turned off by its
> > upstream port driver.
> > 
> > Commit 37a3a98ef601 ("ALSA: hda - Enable runtime PM only for
> > discrete GPU") only allows HDA to be runtime suspended once GPU is
> > bound, to keep APU's HDA working.
> > 
> > However, HDA on dGPU isn't that useful if dGPU is not bound to any
> > driver.  So let's relax the runtime suspend requirement for dGPU's HDA
> > function, to disable the power source to save lots of power.
> > 
> > BugLink: https://bugs.launchpad.net/bugs/1840835
> > Fixes: b516ea586d71 ("PCI: Enable NVIDIA HDA controllers")
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> 
> Do you still have any concern on this patch?
> Please merge [v5 1/2] and this patch [v4 2/2] if you think it's good.

Sorry for the late reply, as I've been off for a few weeks.
Now I applied both patches for 5.4.


Thanks!

Takashi

> 
> Thanks!
> 
> Kai-Heng
> 
> > ---
> > v4:
> > - Find upstream port, it's callee's responsibility now.
> > v3:
> > - Make changelog more clear.
> > v2:
> > - Change wording.
> > - Rebase to Tiwai's branch.
> > sound/pci/hda/hda_intel.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > index 240f4ca76391..e63b871343e5 100644
> > --- a/sound/pci/hda/hda_intel.c
> > +++ b/sound/pci/hda/hda_intel.c
> > @@ -1280,11 +1280,17 @@ static void init_vga_switcheroo(struct azx *chip)
> > {
> > 	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
> > 	struct pci_dev *p = get_bound_vga(chip->pci);
> > +	struct pci_dev *parent;
> > 	if (p) {
> > 		dev_info(chip->card->dev,
> > 			 "Handle vga_switcheroo audio client\n");
> > 		hda->use_vga_switcheroo = 1;
> > -		chip->bus.keep_power = 1; /* cleared in either gpu_bound op or codec probe */
> > +
> > +		/* cleared in either gpu_bound op or codec probe, or when its
> > +		 * upstream port has _PR3 (i.e. dGPU).
> > +		 */
> > +		parent = pci_upstream_bridge(p);
> > +		chip->bus.keep_power = parent ? !pci_pr3_present(parent) : 1;
> > 		chip->driver_caps |= AZX_DCAPS_PM_RUNTIME;
> > 		pci_dev_put(p);
> > 	}
> > -- 
> > 2.17.1
> > 
> 
>