[igt-dev] [PATCH i-g-t] tests/i915_pm_rpm: Try the standard "ddc" symlink for i2c read

[Kamil Konieczny]

Hi Ville,
On 2023-07-05 at 22:34:54 +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The driver may provide the standard "ddc" symlink in sysfs,
> try that first for the i2c read, then fall back to the old
> i915 specific stuff.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Reviewed-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>

> ---
>  tests/i915/i915_pm_rpm.c | 23 +++++++++++++++++++++--
>  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/i915/i915_pm_rpm.c b/tests/i915/i915_pm_rpm.c
> index 4ce83f27f86a..17413ffe5e0f 100644
> --- a/tests/i915/i915_pm_rpm.c
> +++ b/tests/i915/i915_pm_rpm.c
> @@ -861,13 +861,15 @@ static void assert_drm_infos_equal(struct compare_data *d1,
>  		assert_drm_crtcs_equal(d1->crtcs[i], d2->crtcs[i]);
>  }
>  
> -static bool find_i2c_path(const char *connector_name, char *i2c_path)
> +static bool find_i2c_path(const char *connector_name,
> +			  char *i2c_path, size_t i2c_path_size)
>  {
>  	struct dirent *dirent;
>  	DIR *dir;
>  	int sysfs_card_fd = igt_sysfs_open(drm_fd);
>  	int connector_fd = -1;
>  	bool found_i2c_file = false;
> +	ssize_t r;
>  
>  	dir = fdopendir(sysfs_card_fd);
>  	igt_assert(dir);
> @@ -889,9 +891,24 @@ static bool find_i2c_path(const char *connector_name, char *i2c_path)
>  	if (connector_fd < 0)
>  		return false;
>  
> +	/* try the standard "ddc" symlink first */
> +	r = readlinkat(connector_fd, "ddc", i2c_path, i2c_path_size);
> +	if (r > 0 && r != i2c_path_size) {
> +		int num;
> +
> +		i2c_path[r] = '\0';
> +
> +		if (sscanf(basename(i2c_path), "i2c-%d", &num) == 1) {
> +			snprintf(i2c_path, i2c_path_size, "/dev/i2c-%d", num);
> +			return true;
> +		}
> +	}
> +
>  	dir = fdopendir(connector_fd);
>  	igt_assert(dir);
>  
> +	/* fall back to old "i2c-?" symlink */
> +	/* FIXME nuke this at some point */
>  	while ((dirent = readdir(dir))) {
>  		if (strncmp(dirent->d_name, "i2c-", 4) == 0) {
>  			sprintf(i2c_path, "/dev/%s", dirent->d_name);
> @@ -926,10 +943,12 @@ static bool i2c_read_edid(const char *connector_name, unsigned char *edid)
>  		.nmsgs = 2,
>  	};
>  
> -	result = find_i2c_path(connector_name, i2c_path);
> +	result = find_i2c_path(connector_name, i2c_path, sizeof(i2c_path));
>  	if (!result)
>  		return false;
>  
> +	igt_info("Testing %s %s\n", connector_name, i2c_path);
> +
>  	fd = open(i2c_path, O_RDWR);
>  	igt_assert_neq(fd, -1);
>  
> -- 
> 2.39.3
>