Nouveau - Jul 2016 - [PATCH v2 2/4] drm/nouveau/acpi: return supported DSM functions

Hi,

Here are two patches to fix an issue reported on kernel bugzilla (infinite loop
due to unchecked function) and a more important fix to fix hanging Optimus
machines when runtime PM is enabled (with pm/pci patches).

See the first version[1] for a background on the fixed problems. This is the
second revision of incorporating feedback from Emil Velikov (patch 1), Mika
Westerberg (patch 4). Patches 2 and 3 are unchanged.
The previous patchset had R-b from Hans de Goede, I think they are still valid.

Noteworthy is that the fourth patch now checks directly for _PR3. The commit
message is updated to emphasize that memory/disk corruption is fixed for some
machines.


This patchset can be merged before or after the pci/pm changes[2] (expected to
be merged for 4.8), see the original posting[1] for consequences. I have tested
it on top of v4.7-rc5. To make patch four work properly, Lukas' RPM
refcounting
patches should be included. A similar (open/new) RPM refcounting issue in
snd-hda-intel should also be fixed. Otherwise the bridge will not really sleep.

There is another minor patch for nouveau_pr3_present, but it is not included
here because it depends on visibility of pci_bridge_d3_possible(). I'll send
a
separate mail for this to linux-pci.

Kind regards,
Peter

 [1]: https://lists.freedesktop.org/archives/nouveau/2016-May/025116.html
 [2]: https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/?h=pci/pm

Peter Wu (4):
  drm/nouveau/acpi: ensure matching ACPI handle and supported functions
  drm/nouveau/acpi: return supported DSM functions
  drm/nouveau/acpi: check for function 0x1B before using it
  drm/nouveau/acpi: fix lockup with PCIe runtime PM

 drivers/gpu/drm/nouveau/nouveau_acpi.c | 103 +++++++++++++++++++++------------
 1 file changed, 66 insertions(+), 37 deletions(-)

-- 
2.9.0

Ensure that the returned set of supported DSM functions (MUX, Optimus)
match the ACPI handle that is set in nouveau_dsm_pci_probe.

As there are no machines with a MUX function on just one PCI device and
an Optimus on another, there should not be a functional impact. This
change however makes this implicit assumption more obvious.

Convert int to bool and rename has_dsm to has_mux while at it. Let the
caller set nouveau_dsm_priv.dhandle as needed.

 v2: pass dhandle to the caller.

Signed-off-by: Peter Wu <peter at lekensteyn.nl>
---
 drivers/gpu/drm/nouveau/nouveau_acpi.c | 58 +++++++++++++++-------------------
 1 file changed, 26 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c
b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index db76b94..886a67c 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -57,9 +57,6 @@ bool nouveau_is_v1_dsm(void) {
 	return nouveau_dsm_priv.dsm_detected;
 }
 
-#define NOUVEAU_DSM_HAS_MUX 0x1
-#define NOUVEAU_DSM_HAS_OPT 0x2
-
 #ifdef CONFIG_VGA_SWITCHEROO
 static const char nouveau_dsm_muid[] = {
 	0xA0, 0xA0, 0x95, 0x9D, 0x60, 0x00, 0x48, 0x4D,
@@ -212,26 +209,33 @@ static const struct vga_switcheroo_handler
nouveau_dsm_handler = {
 	.get_client_id = nouveau_dsm_get_client_id,
 };
 
-static int nouveau_dsm_pci_probe(struct pci_dev *pdev)
+static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle
*dhandle_out,
+				  bool *has_mux, bool *has_opt)
 {
 	acpi_handle dhandle;
-	int retval = 0;
+	bool supports_mux;
+	bool supports_opt;
 
 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
-		return false;
+		return;
 
 	if (!acpi_has_method(dhandle, "_DSM"))
-		return false;
+		return;
 
-	if (acpi_check_dsm(dhandle, nouveau_dsm_muid, 0x00000102,
-			   1 << NOUVEAU_DSM_POWER))
-		retval |= NOUVEAU_DSM_HAS_MUX;
+	supports_mux = acpi_check_dsm(dhandle, nouveau_dsm_muid, 0x00000102,
+				      1 << NOUVEAU_DSM_POWER);
+	supports_opt = nouveau_check_optimus_dsm(dhandle);
 
-	if (nouveau_check_optimus_dsm(dhandle))
-		retval |= NOUVEAU_DSM_HAS_OPT;
+	/* Does not look like a Nvidia device. */
+	if (!supports_mux && !supports_opt)
+		return;
 
-	if (retval & NOUVEAU_DSM_HAS_OPT) {
+	*dhandle_out = dhandle;
+	*has_mux = supports_mux;
+	*has_opt = supports_opt;
+
+	if (supports_opt) {
 		uint32_t result;
 		nouveau_optimus_dsm(dhandle, NOUVEAU_DSM_OPTIMUS_CAPS, 0,
 				    &result);
@@ -240,10 +244,6 @@ static int nouveau_dsm_pci_probe(struct pci_dev *pdev)
 			 (result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " :
"",
 			 (result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec
supported" : "");
 	}
-	if (retval)
-		nouveau_dsm_priv.dhandle = dhandle;
-
-	return retval;
 }
 
 static bool nouveau_dsm_detect(void)
@@ -251,11 +251,11 @@ static bool nouveau_dsm_detect(void)
 	char acpi_method_name[255] = { 0 };
 	struct acpi_buffer buffer = {sizeof(acpi_method_name), acpi_method_name};
 	struct pci_dev *pdev = NULL;
-	int has_dsm = 0;
-	int has_optimus = 0;
+	acpi_handle dhandle = NULL;
+	bool has_mux = false;
+	bool has_optimus = false;
 	int vga_count = 0;
 	bool guid_valid;
-	int retval;
 	bool ret = false;
 
 	/* lookup the MXM GUID */
@@ -268,32 +268,26 @@ static bool nouveau_dsm_detect(void)
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL)
{
 		vga_count++;
 
-		retval = nouveau_dsm_pci_probe(pdev);
-		if (retval & NOUVEAU_DSM_HAS_MUX)
-			has_dsm |= 1;
-		if (retval & NOUVEAU_DSM_HAS_OPT)
-			has_optimus = 1;
+		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus);
 	}
 
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL)
{
 		vga_count++;
 
-		retval = nouveau_dsm_pci_probe(pdev);
-		if (retval & NOUVEAU_DSM_HAS_MUX)
-			has_dsm |= 1;
-		if (retval & NOUVEAU_DSM_HAS_OPT)
-			has_optimus = 1;
+		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus);
 	}
 
 	/* find the optimus DSM or the old v1 DSM */
-	if (has_optimus == 1) {
+	if (has_optimus) {
+		nouveau_dsm_priv.dhandle = dhandle;
 		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
 			&buffer);
 		printk(KERN_INFO "VGA switcheroo: detected Optimus DSM method %s
handle\n",
 			acpi_method_name);
 		nouveau_dsm_priv.optimus_detected = true;
 		ret = true;
-	} else if (vga_count == 2 && has_dsm && guid_valid) {
+	} else if (vga_count == 2 && has_mux && guid_valid) {
+		nouveau_dsm_priv.dhandle = dhandle;
 		acpi_get_name(nouveau_dsm_priv.dhandle, ACPI_FULL_PATHNAME,
 			&buffer);
 		printk(KERN_INFO "VGA switcheroo: detected DSM switching method %s
handle\n",
-- 
2.9.0

Return the set of supported functions to the caller. No functional
changes.

Signed-off-by: Peter Wu <peter at lekensteyn.nl>
---
 drivers/gpu/drm/nouveau/nouveau_acpi.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c
b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index 886a67c..572ac30 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -107,7 +107,7 @@ static int nouveau_optimus_dsm(acpi_handle handle, int func,
int arg, uint32_t *
  * requirements on the fourth parameter, so a private implementation
  * instead of using acpi_check_dsm().
  */
-static int nouveau_check_optimus_dsm(acpi_handle handle)
+static int nouveau_dsm_get_optimus_functions(acpi_handle handle)
 {
 	int result;
 
@@ -122,7 +122,9 @@ static int nouveau_check_optimus_dsm(acpi_handle handle)
 	 * ACPI Spec v4 9.14.1: if bit 0 is zero, no function is supported.
 	 * If the n-th bit is enabled, function n is supported
 	 */
-	return result & 1 && result & (1 <<
NOUVEAU_DSM_OPTIMUS_CAPS);
+	if (result & 1 && result & (1 <<
NOUVEAU_DSM_OPTIMUS_CAPS))
+		return result;
+	return 0;
 }
 
 static int nouveau_dsm(acpi_handle handle, int func, int arg)
@@ -214,7 +216,7 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev,
acpi_handle *dhandle_out
 {
 	acpi_handle dhandle;
 	bool supports_mux;
-	bool supports_opt;
+	int optimus_funcs;
 
 	dhandle = ACPI_HANDLE(&pdev->dev);
 	if (!dhandle)
@@ -225,17 +227,17 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev,
acpi_handle *dhandle_out
 
 	supports_mux = acpi_check_dsm(dhandle, nouveau_dsm_muid, 0x00000102,
 				      1 << NOUVEAU_DSM_POWER);
-	supports_opt = nouveau_check_optimus_dsm(dhandle);
+	optimus_funcs = nouveau_dsm_get_optimus_functions(dhandle);
 
 	/* Does not look like a Nvidia device. */
-	if (!supports_mux && !supports_opt)
+	if (!supports_mux && !optimus_funcs)
 		return;
 
 	*dhandle_out = dhandle;
 	*has_mux = supports_mux;
-	*has_opt = supports_opt;
+	*has_opt = !!optimus_funcs;
 
-	if (supports_opt) {
+	if (optimus_funcs) {
 		uint32_t result;
 		nouveau_optimus_dsm(dhandle, NOUVEAU_DSM_OPTIMUS_CAPS, 0,
 				    &result);
-- 
2.9.0

Do not unconditionally invoke function 0x1B without checking for its
availability, it leads to an infinite loop on some firmware.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=104791
Fixes: 5addcf0a5f0fad ("nouveau: add runtime PM support (v0.9)")
Signed-off-by: Peter Wu <peter at lekensteyn.nl>
---
 drivers/gpu/drm/nouveau/nouveau_acpi.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c
b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index 572ac30..ad273ad 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -45,6 +45,7 @@
 static struct nouveau_dsm_priv {
 	bool dsm_detected;
 	bool optimus_detected;
+	bool optimus_flags_detected;
 	acpi_handle dhandle;
 	acpi_handle rom_handle;
 } nouveau_dsm_priv;
@@ -212,7 +213,8 @@ static const struct vga_switcheroo_handler
nouveau_dsm_handler = {
 };
 
 static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle
*dhandle_out,
-				  bool *has_mux, bool *has_opt)
+				  bool *has_mux, bool *has_opt,
+				  bool *has_opt_flags)
 {
 	acpi_handle dhandle;
 	bool supports_mux;
@@ -236,6 +238,7 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev,
acpi_handle *dhandle_out
 	*dhandle_out = dhandle;
 	*has_mux = supports_mux;
 	*has_opt = !!optimus_funcs;
+	*has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS);
 
 	if (optimus_funcs) {
 		uint32_t result;
@@ -256,6 +259,7 @@ static bool nouveau_dsm_detect(void)
 	acpi_handle dhandle = NULL;
 	bool has_mux = false;
 	bool has_optimus = false;
+	bool has_optimus_flags = false;
 	int vga_count = 0;
 	bool guid_valid;
 	bool ret = false;
@@ -270,13 +274,15 @@ static bool nouveau_dsm_detect(void)
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev)) != NULL)
{
 		vga_count++;
 
-		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus);
+		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
+				      &has_optimus_flags);
 	}
 
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL)
{
 		vga_count++;
 
-		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus);
+		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
+				      &has_optimus_flags);
 	}
 
 	/* find the optimus DSM or the old v1 DSM */
@@ -287,6 +293,7 @@ static bool nouveau_dsm_detect(void)
 		printk(KERN_INFO "VGA switcheroo: detected Optimus DSM method %s
handle\n",
 			acpi_method_name);
 		nouveau_dsm_priv.optimus_detected = true;
+		nouveau_dsm_priv.optimus_flags_detected = has_optimus_flags;
 		ret = true;
 	} else if (vga_count == 2 && has_mux && guid_valid) {
 		nouveau_dsm_priv.dhandle = dhandle;
@@ -320,8 +327,9 @@ void nouveau_switcheroo_optimus_dsm(void)
 	if (!nouveau_dsm_priv.optimus_detected)
 		return;
 
-	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FLAGS,
-			    0x3, &result);
+	if (nouveau_dsm_priv.optimus_flags_detected)
+		nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_FLAGS,
+				    0x3, &result);
 
 	nouveau_optimus_dsm(nouveau_dsm_priv.dhandle, NOUVEAU_DSM_OPTIMUS_CAPS,
 		NOUVEAU_DSM_OPTIMUS_SET_POWERDOWN, &result);
-- 
2.9.0

Since "PCI: Add runtime PM support for PCIe ports", the parent PCIe
port
can be runtime-suspended which disables power resources via ACPI. This
is incompatible with DSM, resulting in a GPU device which is still in D3
and locks up the kernel on resume (on a Clevo P651RA, GTX965M).

Mirror the behavior of Windows 8 and newer[1] (as observed via an AMLi
debugger trace) and stop using the DSM functions for D3cold when power
resources are available on the parent PCIe port.

pci_d3cold_disable() is not used because on some machines, the old DSM
method is broken. On a Lenovo T440p (GT 730M) memory and disk corruption
would occur, but that is fixed with this patch[2].

 [1]:
https://msdn.microsoft.com/windows/hardware/drivers/bringup/firmware-requirements-for-d3cold
 [2]:
https://github.com/Bumblebee-Project/bbswitch/issues/78#issuecomment-223549072

 v2: simply check directly for _PR3. Added affected machines.

Signed-off-by: Peter Wu <peter at lekensteyn.nl>
---
 drivers/gpu/drm/nouveau/nouveau_acpi.c | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c
b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index ad273ad..38a6445 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -46,6 +46,7 @@ static struct nouveau_dsm_priv {
 	bool dsm_detected;
 	bool optimus_detected;
 	bool optimus_flags_detected;
+	bool optimus_skip_dsm;
 	acpi_handle dhandle;
 	acpi_handle rom_handle;
 } nouveau_dsm_priv;
@@ -212,9 +213,26 @@ static const struct vga_switcheroo_handler
nouveau_dsm_handler = {
 	.get_client_id = nouveau_dsm_get_client_id,
 };
 
+/* Firmware supporting Windows 8 or later do not use _DSM to put the device
into
+ * D3cold, they instead rely on disabling power resources on the parent. */
+static bool nouveau_pr3_present(struct pci_dev *pdev)
+{
+	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
+	struct acpi_device *parent_adev;
+
+	if (!parent_pdev)
+		return false;
+
+	parent_adev = ACPI_COMPANION(&parent_pdev->dev);
+	if (!parent_adev)
+		return false;
+
+	return acpi_has_method(parent_adev->handle, "_PR3");
+}
+
 static void nouveau_dsm_pci_probe(struct pci_dev *pdev, acpi_handle
*dhandle_out,
 				  bool *has_mux, bool *has_opt,
-				  bool *has_opt_flags)
+				  bool *has_opt_flags, bool *has_pr3)
 {
 	acpi_handle dhandle;
 	bool supports_mux;
@@ -239,6 +257,7 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev,
acpi_handle *dhandle_out
 	*has_mux = supports_mux;
 	*has_opt = !!optimus_funcs;
 	*has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS);
+	*has_pr3 = false;
 
 	if (optimus_funcs) {
 		uint32_t result;
@@ -248,6 +267,8 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev,
acpi_handle *dhandle_out
 			 (result & OPTIMUS_ENABLED) ? "enabled" :
"disabled",
 			 (result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " :
"",
 			 (result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec
supported" : "");
+
+		*has_pr3 = nouveau_pr3_present(pdev);
 	}
 }
 
@@ -260,6 +281,7 @@ static bool nouveau_dsm_detect(void)
 	bool has_mux = false;
 	bool has_optimus = false;
 	bool has_optimus_flags = false;
+	bool has_power_resources = false;
 	int vga_count = 0;
 	bool guid_valid;
 	bool ret = false;
@@ -275,14 +297,14 @@ static bool nouveau_dsm_detect(void)
 		vga_count++;
 
 		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
-				      &has_optimus_flags);
+				      &has_optimus_flags, &has_power_resources);
 	}
 
 	while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL)
{
 		vga_count++;
 
 		nouveau_dsm_pci_probe(pdev, &dhandle, &has_mux, &has_optimus,
-				      &has_optimus_flags);
+				      &has_optimus_flags, &has_power_resources);
 	}
 
 	/* find the optimus DSM or the old v1 DSM */
@@ -292,8 +314,11 @@ static bool nouveau_dsm_detect(void)
 			&buffer);
 		printk(KERN_INFO "VGA switcheroo: detected Optimus DSM method %s
handle\n",
 			acpi_method_name);
+		if (has_power_resources)
+			pr_info("nouveau: detected PR support, will not use DSM\n");
 		nouveau_dsm_priv.optimus_detected = true;
 		nouveau_dsm_priv.optimus_flags_detected = has_optimus_flags;
+		nouveau_dsm_priv.optimus_skip_dsm = has_power_resources;
 		ret = true;
 	} else if (vga_count == 2 && has_mux && guid_valid) {
 		nouveau_dsm_priv.dhandle = dhandle;
@@ -324,7 +349,7 @@ void nouveau_register_dsm_handler(void)
 void nouveau_switcheroo_optimus_dsm(void)
 {
 	u32 result = 0;
-	if (!nouveau_dsm_priv.optimus_detected)
+	if (!nouveau_dsm_priv.optimus_detected || nouveau_dsm_priv.optimus_skip_dsm)
 		return;
 
 	if (nouveau_dsm_priv.optimus_flags_detected)
-- 
2.9.0

On Fri, Jul 08, 2016 at 01:38:27AM +0200, Peter Wu
wrote:
> Since "PCI: Add runtime PM support for PCIe ports", the parent
PCIe port
> can be runtime-suspended which disables power resources via ACPI. This
> is incompatible with DSM, resulting in a GPU device which is still in D3
> and locks up the kernel on resume (on a Clevo P651RA, GTX965M).
> 
> Mirror the behavior of Windows 8 and newer[1] (as observed via an AMLi
> debugger trace) and stop using the DSM functions for D3cold when power
> resources are available on the parent PCIe port.
> 
> pci_d3cold_disable() is not used because on some machines, the old DSM
> method is broken. On a Lenovo T440p (GT 730M) memory and disk corruption
> would occur, but that is fixed with this patch[2].
Fair enough.
>  [1]:
https://msdn.microsoft.com/windows/hardware/drivers/bringup/firmware-requirements-for-d3cold
>  [2]:
https://github.com/Bumblebee-Project/bbswitch/issues/78#issuecomment-223549072
> 
>  v2: simply check directly for _PR3. Added affected machines.
> 
> Signed-off-by: Peter Wu <peter at lekensteyn.nl>
One nitpick below but otherwise looks reasonable to me.

Reviewed-by: Mika Westerberg <mika.westerberg at linux.intel.com>

BTW, thanks for doing this :)
> ---
>  drivers/gpu/drm/nouveau/nouveau_acpi.c | 33
+++++++++++++++++++++++++++++----
>  1 file changed, 29 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c
b/drivers/gpu/drm/nouveau/nouveau_acpi.c
> index ad273ad..38a6445 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
> @@ -46,6 +46,7 @@ static struct nouveau_dsm_priv {
>  	bool dsm_detected;
>  	bool optimus_detected;
>  	bool optimus_flags_detected;
> +	bool optimus_skip_dsm;
>  	acpi_handle dhandle;
>  	acpi_handle rom_handle;
>  } nouveau_dsm_priv;
> @@ -212,9 +213,26 @@ static const struct vga_switcheroo_handler
nouveau_dsm_handler = {
>  	.get_client_id = nouveau_dsm_get_client_id,
>  };
>  
> +/* Firmware supporting Windows 8 or later do not use _DSM to put the
device into
> + * D3cold, they instead rely on disabling power resources on the parent.
*/
You should follow standard block comment style here.
> +static bool nouveau_pr3_present(struct pci_dev *pdev)
> +{
> +	struct pci_dev *parent_pdev = pci_upstream_bridge(pdev);
> +	struct acpi_device *parent_adev;
> +
> +	if (!parent_pdev)
> +		return false;
> +
> +	parent_adev = ACPI_COMPANION(&parent_pdev->dev);
> +	if (!parent_adev)
> +		return false;
> +
> +	return acpi_has_method(parent_adev->handle, "_PR3");
> +}

Hi,

On 08-07-16 01:38, Peter Wu wrote:
> Hi,
>
> Here are two patches to fix an issue reported on kernel bugzilla (infinite
loop
> due to unchecked function) and a more important fix to fix hanging Optimus
> machines when runtime PM is enabled (with pm/pci patches).
>
> See the first version[1] for a background on the fixed problems. This is
the
> second revision of incorporating feedback from Emil Velikov (patch 1), Mika
> Westerberg (patch 4). Patches 2 and 3 are unchanged.
> The previous patchset had R-b from Hans de Goede, I think they are still
valid.
>
> Noteworthy is that the fourth patch now checks directly for _PR3. The
commit
> message is updated to emphasize that memory/disk corruption is fixed for
some
> machines.
>
>
> This patchset can be merged before or after the pci/pm changes[2] (expected
to
> be merged for 4.8), see the original posting[1] for consequences. I have
tested
> it on top of v4.7-rc5. To make patch four work properly, Lukas' RPM
refcounting
> patches should be included. A similar (open/new) RPM refcounting issue in
> snd-hda-intel should also be fixed. Otherwise the bridge will not really
sleep.
>
> There is another minor patch for nouveau_pr3_present, but it is not
included
> here because it depends on visibility of pci_bridge_d3_possible(). I'll
send a
> separate mail for this to linux-pci.
Patches 1 - 3 are:

Reviewed-by: Hans de Goede <hdegoede at redhat.com>

Patch 4 looks good to me too, but I'm not familiar enough with the
pci-e pm stuff to feel comfortable acking it.

Regards,

Hans


>
> Kind regards,
> Peter
>
>  [1]: https://lists.freedesktop.org/archives/nouveau/2016-May/025116.html
>  [2]:
https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/?h=pci/pm
>
> Peter Wu (4):
>   drm/nouveau/acpi: ensure matching ACPI handle and supported functions
>   drm/nouveau/acpi: return supported DSM functions
>   drm/nouveau/acpi: check for function 0x1B before using it
>   drm/nouveau/acpi: fix lockup with PCIe runtime PM
>
>  drivers/gpu/drm/nouveau/nouveau_acpi.c | 103
+++++++++++++++++++++------------
>  1 file changed, 66 insertions(+), 37 deletions(-)
>