[PATCH v2 1/2] PCI: Add support for a functional level reset based on _RST method

[PATCH v2 1/2] PCI: Add support for a functional level reset based on _RST method

[Shanker Donthineni]

The _RST is a standard method specified in the ACPI specification. It
provides a function level reset when it is described in the acpi_device
context associated with PCI-device.

Implement a new reset function pci_dev_acpi_reset() for probing RST
method and execute if it is defined in the firmware.

The ACPI based reset is called after the device-specific reset and
before standard PCI hardware resets.

Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
---
 drivers/pci/pci.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 16a17215f633..6dadb19848c2 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5054,6 +5054,35 @@ static void pci_dev_restore(struct pci_dev *dev)
 		err_handler->reset_done(dev);
 }
 
+/**
+ * pci_dev_acpi_reset - do a function level reset using _RST method
+ * @dev: device to reset
+ * @probe: check if _RST method is included in the acpi_device context.
+ */
+static int pci_dev_acpi_reset(struct pci_dev *dev, int probe)
+{
+#ifdef CONFIG_ACPI
+	acpi_handle handle = ACPI_HANDLE(&dev->dev);
+
+	/* Return -ENOTTY if _RST method is not included in the dev context */
+	if (!handle || !acpi_has_method(handle, "_RST"))
+		return -ENOTTY;
+
+	/* Return 0 for probe phase indicating that we can reset this device */
+	if (probe)
+		return 0;
+
+	/* Invoke _RST() method to perform a function level reset */
+	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) {
+		pci_warn(dev, "Failed to reset the device\n");
+		return -EINVAL;
+	}
+	return 0;
+#else
+	return -ENOTTY;
+#endif
+}
+
 /**
  * __pci_reset_function_locked - reset a PCI device function while holding
  * the @dev mutex lock.
@@ -5089,6 +5118,9 @@ int __pci_reset_function_locked(struct pci_dev *dev)
 	 * reset mechanisms might be broken on the device.
 	 */
 	rc = pci_dev_specific_reset(dev, 0);
+	if (rc != -ENOTTY)
+		return rc;
+	rc = pci_dev_acpi_reset(dev, 0);
 	if (rc != -ENOTTY)
 		return rc;
 	if (pcie_has_flr(dev)) {
@@ -5127,6 +5159,9 @@ int pci_probe_reset_function(struct pci_dev *dev)
 	might_sleep();
 
 	rc = pci_dev_specific_reset(dev, 1);
+	if (rc != -ENOTTY)
+		return rc;
+	rc = pci_dev_acpi_reset(dev, 1);
 	if (rc != -ENOTTY)
 		return rc;
 	if (pcie_has_flr(dev))
-- 
2.17.1

[PATCH v2 2/2] PCI: Enable NO_BUS_RESET quirk for Nvidia GPUs

[Shanker Donthineni]

On select platforms, some Nvidia GPU devices do not work with SBR.
Triggering SBR would leave the device inoperable for the current
system boot. It requires a system hard-reboot to get the GPU device
back to normal operating condition post-SBR. For the affected
devices, enable NO_BUS_RESET quirk to fix the issue.

This issue will be fixed in the next generation of hardware.

Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
---
Changes since v1:
 - Split patch into 2, code for handling _RST and SBR specific quirk
 - The RST based reset is called as a first-class mechanism in the reset code path

 drivers/pci/quirks.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 653660e3ba9e..1da80e772ee1 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3913,6 +3913,18 @@ static int delay_250ms_after_flr(struct pci_dev *dev, int probe)
 	return 0;
 }
 
+/*
+ * Some Nvidia GPU devices do not work with bus reset, SBR needs to be
+ * prevented for those affected devices.
+ */
+static void quirk_nvidia_no_bus_reset(struct pci_dev *dev)
+{
+	if ((dev->device & 0xffc0) == 0x2340)
+		dev->dev_flags |= PCI_DEV_FLAGS_NO_BUS_RESET;
+}
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
+			 quirk_nvidia_no_bus_reset);
+
 static const struct pci_dev_reset_methods pci_dev_reset_methods[] = {
 	{ PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82599_SFP_VF,
 		 reset_intel_82599_sfp_virtfn },
-- 
2.17.1

Re: [PATCH v2 1/2] PCI: Add support for a functional level reset based on _RST method

[Shanker R Donthineni]

Typo in the commit text  will post v3.

On 4/26/21 9:28 PM, Shanker Donthineni wrote:
> The _RST is a standard method specified in the ACPI specification. It
> provides a function level reset when it is described in the acpi_device
> context associated with PCI-device.
>
> Implement a new reset function pci_dev_acpi_reset() for probing RST
> method and execute if it is defined in the firmware.
>
> The ACPI based reset is called after the device-specific reset and
> before standard PCI hardware resets.
>
> Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
> ---
>  drivers/pci/pci.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 16a17215f633..6dadb19848c2 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -5054,6 +5054,35 @@ static void pci_dev_restore(struct pci_dev *dev)
>  		err_handler->reset_done(dev);
>  }
>  
> +/**
> + * pci_dev_acpi_reset - do a function level reset using _RST method
> + * @dev: device to reset
> + * @probe: check if _RST method is included in the acpi_device context.
> + */
> +static int pci_dev_acpi_reset(struct pci_dev *dev, int probe)
> +{
> +#ifdef CONFIG_ACPI
> +	acpi_handle handle = ACPI_HANDLE(&dev->dev);
> +
> +	/* Return -ENOTTY if _RST method is not included in the dev context */
> +	if (!handle || !acpi_has_method(handle, "_RST"))
> +		return -ENOTTY;
> +
> +	/* Return 0 for probe phase indicating that we can reset this device */
> +	if (probe)
> +		return 0;
> +
> +	/* Invoke _RST() method to perform a function level reset */
> +	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_RST", NULL, NULL))) {
> +		pci_warn(dev, "Failed to reset the device\n");
> +		return -EINVAL;
> +	}
> +	return 0;
> +#else
> +	return -ENOTTY;
> +#endif
> +}
> +
>  /**
>   * __pci_reset_function_locked - reset a PCI device function while holding
>   * the @dev mutex lock.
> @@ -5089,6 +5118,9 @@ int __pci_reset_function_locked(struct pci_dev *dev)
>  	 * reset mechanisms might be broken on the device.
>  	 */
>  	rc = pci_dev_specific_reset(dev, 0);
> +	if (rc != -ENOTTY)
> +		return rc;
> +	rc = pci_dev_acpi_reset(dev, 0);
>  	if (rc != -ENOTTY)
>  		return rc;
>  	if (pcie_has_flr(dev)) {
> @@ -5127,6 +5159,9 @@ int pci_probe_reset_function(struct pci_dev *dev)
>  	might_sleep();
>  
>  	rc = pci_dev_specific_reset(dev, 1);
> +	if (rc != -ENOTTY)
> +		return rc;
> +	rc = pci_dev_acpi_reset(dev, 1);
>  	if (rc != -ENOTTY)
>  		return rc;
>  	if (pcie_has_flr(dev))