[igt-dev] [PATCH i-g-t 2/8] lib/igt_sriov_device: add helper for opening VF device

[Kamil Konieczny]

Hi Lukasz,
On 2023-11-20 at 15:14:53 +0100, Lukasz Laguna wrote:
> From: Katarzyna Dec <katarzyna.dec at intel.com>
> 
> Helper opens DRM device node and returns its file descriptor.
> 
> Cc: Marcin Bernatowicz <marcin.bernatowicz at linux.intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Signed-off-by: Katarzyna Dec <katarzyna.dec at intel.com>
> Signed-off-by: Lukasz Laguna <lukasz.laguna at intel.com>
> ---
>  lib/drmtest.c          | 17 +++++++++++----
>  lib/drmtest.h          |  1 +
>  lib/igt_sriov_device.c | 47 ++++++++++++++++++++++++++++++++++++++++++
>  lib/igt_sriov_device.h |  1 +
>  4 files changed, 62 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/drmtest.c b/lib/drmtest.c
> index f0b97e362..d8b7aace5 100644
> --- a/lib/drmtest.c
> +++ b/lib/drmtest.c
> @@ -245,7 +245,16 @@ static void log_opened_device_path(const char *device_path)
>  	igt_info("Opened device: %s\n", item->path);
>  }
>  
> -static int open_device(const char *name, unsigned int chipset)
> +/**
> + * drm_open_device:
> + * @name: DRM node name
> + * @chipset: OR'd flags for each chipset to search, eg. #DRIVER_INTEL
> + *
> + * Open a drm legacy device node.
> + *
> + * Returns: DRM file descriptor or -1 on error
> + */
> +int drm_open_device(const char *name, unsigned int chipset)

Please name it __drm_open_device as this function will not assert.

>  {
>  	const char *forced;
>  	char dev_name[16] = "";
> @@ -350,7 +359,7 @@ static int __search_and_open(const char *base, int offset, unsigned int chipset,
>  		if (_is_already_opened(name, as_idx))
>  			continue;
>  
> -		fd = open_device(name, chipset);
> +		fd = drm_open_device(name, chipset);
>  		if (fd != -1)
>  			return fd;
>  	}
> @@ -392,13 +401,13 @@ static int __open_driver_exact(const char *name, unsigned int chipset)
>  {
>  	int fd;
>  
> -	fd = open_device(name, chipset);
> +	fd = drm_open_device(name, chipset);
>  	if (fd != -1)
>  		return fd;
>  
>  	drm_load_module(chipset);
>  
> -	return open_device(name, chipset);
> +	return drm_open_device(name, chipset);
>  }
>  
>  /*
> diff --git a/lib/drmtest.h b/lib/drmtest.h
> index 909a0c12c..9c040a136 100644
> --- a/lib/drmtest.h
> +++ b/lib/drmtest.h
> @@ -98,6 +98,7 @@ void __set_forced_driver(const char *name);
>   */
>  #define ALIGN_DOWN(x, a)	ALIGN((x) - ((a) - 1), (a))
>  
> +int drm_open_device(const char *name, unsigned int chipset);
>  void drm_load_module(unsigned int chipset);
>  int drm_open_driver(int chipset);
>  int drm_open_driver_master(int chipset);
> diff --git a/lib/igt_sriov_device.c b/lib/igt_sriov_device.c
> index c5c594c2c..cd00c7c5d 100644
> --- a/lib/igt_sriov_device.c
> +++ b/lib/igt_sriov_device.c
> @@ -3,8 +3,10 @@
>   * Copyright(c) 2023 Intel Corporation. All rights reserved.
>   */
>  
> +#include <dirent.h>
>  #include <errno.h>
>  
> +#include "drmtest.h"
>  #include "igt_core.h"
>  #include "igt_sriov_device.h"
>  #include "igt_sysfs.h"
> @@ -211,3 +213,48 @@ void igt_sriov_disable_driver_autoprobe(int pf)
>  {
>  	pf_attr_set_u32(pf,  "device/sriov_drivers_autoprobe", false);
>  }
> +
> +/**
> + * igt_sriov_open_vf_drm_device - Open VF DRM device node
> + * @pf: PF device file descriptor
> + * @vf_num: VF number (1-based to identify single VF)
> + *
> + * Open DRM device node for given VF.
> + *
> + * Return:
> + * VF file descriptor or -1 on error.
> + */
> +int igt_sriov_open_vf_drm_device(int pf, unsigned int vf_num)
> +{
> +	char dir_path[PATH_MAX], path[PATH_MAX], dev_name[16];
> +	DIR *dir;
> +	struct dirent *de;
> +	bool found = false;
> +
> +	igt_assert(vf_num > 0);
> +
> +	if (!igt_sysfs_path(pf, dir_path, sizeof(dir_path)))
> +		return -1;
> +	/* vf_num is 1-based, but virtfn is 0-based */
> +	snprintf(path, sizeof(path), "/device/virtfn%u/drm", vf_num - 1);
> +	strncat(dir_path, path, sizeof(dir_path) - strlen(dir_path));
--- ^^^^^^^

Make it in one go with snprintf above.
	snprintf(path, sizeof(path), "%s/device/virtfn%u/drm", dir_path, vf_num - 1);

Then:
	dir = opendir(path);

Regards,
Kamil

> +
> +	dir = opendir(dir_path);
> +	if (!dir)
> +		return -1;
> +	while ((de = readdir(dir))) {
> +		unsigned int card_num;
> +
> +		if (sscanf(de->d_name, "card%d", &card_num) == 1) {
> +			snprintf(dev_name, sizeof(dev_name), "/dev/dri/card%u", card_num);
> +			found = true;
> +			break;
> +		}
> +	}
> +	closedir(dir);
> +
> +	if (!found)
> +		return -1;
> +
> +	return drm_open_device(dev_name, DRIVER_ANY);
> +}
> diff --git a/lib/igt_sriov_device.h b/lib/igt_sriov_device.h
> index 337fdf84b..4e57f0dcb 100644
> --- a/lib/igt_sriov_device.h
> +++ b/lib/igt_sriov_device.h
> @@ -25,5 +25,6 @@ void igt_sriov_disable_vfs(int pf);
>  bool igt_sriov_is_driver_autoprobe_enabled(int pf);
>  void igt_sriov_enable_driver_autoprobe(int pf);
>  void igt_sriov_disable_driver_autoprobe(int pf);
> +int igt_sriov_open_vf_drm_device(int pf, unsigned int vf_num);
>  
>  #endif /* __IGT_SRIOV_DEVICE_H__ */
> -- 
> 2.40.0
>