Re: [igt-dev] [PATCH i-g-t 2/2] tests/device_reset: Add warm_reset test

["Tauro, Riana" <riana.tauro@intel.com>]

Hi Anshuman,

On 1/9/2023 5:32 PM, Anshuman Gupta wrote:
> Adding gfx card root port warm reset support
> by triggering secondary bus reset on root port.
> 
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>   lib/igt_pci.c        | 28 ++++++++++++++++++++++++++++
>   lib/igt_pci.h        |  5 +++++
>   tests/device_reset.c | 18 +++++++++++++++---
>   3 files changed, 48 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/igt_pci.c b/lib/igt_pci.c
> index 61aaf939d1..3940a0ee1e 100644
> --- a/lib/igt_pci.c
> +++ b/lib/igt_pci.c
> @@ -51,3 +51,31 @@ int find_pci_cap_offset(struct pci_device *dev, enum pci_cap_id cap_id)
>   {
>   	return find_pci_cap_offset_at(dev, cap_id, PCI_CAPS_START);
>   }
> +
> +/**
> + * igt_pci_bridge_warm_reset:
> + * @dev: pci bridge device
> + *
> + * return:
> + * true on success otherwise false.
> + */
> +bool igt_pci_bridge_warm_reset(struct pci_device *dev)
> +{
> +	uint8_t header_type;
> +	uint16_t bridge_ctl;
> +
> +	if (pci_device_cfg_read_u8(dev, &header_type, PCI_HEADER_TYPE))
> +		return false;
> +
> +	igt_assert_f((header_type & 0x7f) == 1, "PCI device is not a Bridge\n");
> +
> +	if (pci_device_cfg_read_u16(dev, &bridge_ctl, PCI_TYPE_1_HEADER_BRIDGE_CTL))
> +		return false;
> +
> +	bridge_ctl |=  PCI_TYPE_1_SEC_BUS_RESET;
> +
> +	if (pci_device_cfg_write_u16(dev, bridge_ctl, PCI_TYPE_1_HEADER_BRIDGE_CTL))
> +		return false;
> +


The pci code adds a minimum reset duration (Trst) delay after setting 
the bit. Do we need to add the same here?
https://elixir.bootlin.com/linux/latest/source/drivers/pci/pci.c#L5045

Is restoring sequence not necessary?

Thanks
Riana

> +	return true;
> +}
> diff --git a/lib/igt_pci.h b/lib/igt_pci.h
> index 92b9cc3929..f755e4baab 100644
> --- a/lib/igt_pci.h
> +++ b/lib/igt_pci.h
> @@ -12,6 +12,10 @@
>   /* forward declaration */
>   struct pci_device;
>   
> +#define PCI_HEADER_TYPE 0xe
> +#define PCI_TYPE_1_HEADER_BRIDGE_CTL 0x3e > +#define  PCI_TYPE_1_SEC_BUS_RESET (1 << 6)
> +
>   #define PCI_TYPE0_1_HEADER_SIZE 0x40
>   #define PCI_CAPS_START 0x34
>   #define PCI_CFG_SPACE_SIZE 0x100
> @@ -24,5 +28,6 @@ enum pci_cap_id {
>   #define  PCI_SLOT_PWR_CTRL_PRESENT (1 << 1)
>   
>   int find_pci_cap_offset(struct pci_device *dev, enum pci_cap_id cap_id);
> +bool igt_pci_bridge_warm_reset(struct pci_device *dev);
>   
>   #endif
> diff --git a/tests/device_reset.c b/tests/device_reset.c
> index fe26030783..cbb5bef443 100644
> --- a/tests/device_reset.c
> +++ b/tests/device_reset.c
> @@ -22,8 +22,9 @@ IGT_TEST_DESCRIPTION("Examine behavior of a driver on device sysfs reset");
>   #define DEV_BUS_ADDR_LEN 13 /* addr has form 0000:00:00.0 */
>   
>   enum reset {
> -	COLD_RESET,
> -	FLR_RESET
> +	FLR_RESET,
> +	WARM_RESET,
> +	COLD_RESET
>   };
>   
>   /**
> @@ -39,6 +40,7 @@ struct device_data {
>   	} fds;
>   	char dev_bus_addr[DEV_BUS_ADDR_LEN];
>   	bool snd_unload;
> +	struct pci_device *root;
>   };
>   
>   static int __open_sysfs_dir(int fd, const char* path)
> @@ -336,6 +338,8 @@ static void initiate_device_reset(struct device_data *dev, enum reset type)
>   
>   	if (type == FLR_RESET) {
>   		igt_assert(igt_sysfs_set(dev->fds.dev_dir, "reset", "1"));
> +	} else if (type == WARM_RESET) {
> +		igt_assert(igt_pci_bridge_warm_reset(dev->root));
>   	} else if (type == COLD_RESET) {
>   		igt_assert(igt_sysfs_set(dev->fds.slot_dir, "power", "0"));
>   		igt_assert(!igt_sysfs_get_boolean(dev->fds.slot_dir, "power"));
> @@ -404,7 +408,7 @@ static void unbind_reset_rebind(struct device_data *dev, enum reset type)
>   
>   igt_main
>   {
> -	struct device_data dev = { .fds = {-1, -1, -1}, .dev_bus_addr = {0}, };
> +	struct device_data dev = { .fds = {-1, -1, -1}, .dev_bus_addr = {0}, .root = NULL};
>   
>   	igt_fixture {
>   		char dev_path[PATH_MAX];
> @@ -417,6 +421,7 @@ igt_main
>   		set_device_filter(dev_path);
>   
>   		igt_skip_on(!is_sysfs_reset_supported(dev.fds.dev));
> +		dev.root = igt_device_get_pci_root_port(dev.fds.dev);
>   	}
>   
>   	igt_describe("Unbinds driver from device, initiates reset"
> @@ -432,6 +437,13 @@ igt_main
>   		healthcheck(&dev);
>   	}
>   
> +	igt_describe("Unbinds driver from device, initiates warm reset"
> +		     " then rebinds driver to device");
> +	igt_subtest("unbind-warm-reset-rebind") {
> +		unbind_reset_rebind(&dev, WARM_RESET);
> +		healthcheck(&dev);
> +	}
> +
>   	igt_subtest_group {
>   		igt_fixture {
>   			igt_skip_on_f(dev.fds.slot_dir < 0, "Gfx Card does not support any "