Re: [PATCH i-g-t v3 1/1] tests/kms_vrr: Skip LOBF test when aux-less ALPM is not enabled

[Sebastian Brzezinka <sebastian.brzezinka@intel.com>]

Hi Mohammed,

On Mon Mar 2, 2026 at 4:15 PM CET, Mohammed Bilal wrote:
> LOBF (Link Off Between Frames) is a feature introduced in eDP 1.5+
> that can operate in both Aux-less ALPM (Advanced Link Power Management)
> and AUX-Wake ALPM modes.Currently, the test relies on Aux-less
> ALPM support to validate LOBF functionality.
>
> Add a helper to read the Aux-less ALPM status from debugfs and
> skip the LOBF subtest when Aux-less ALPM is not enabled on the
> panel, avoiding false failures on systems that may only support
> AUX-Wake ALPM or lack ALPM support entirely.
>
> v3:
> -Rebase
>
> v2:
> -Update commit message (Jeevan)
> -Update commit message for LOBF/ALPM clarification (Kamil)
> -Rename function to igt_is_aux_less_alpm_enabled (Sebastien)
> -Add explicit null-termination (Sebastien)
> -Add igt_info() log (Sowmiya)
>
> Signed-off-by: Mohammed Bilal <mohammed.bilal@intel.com>
> ---
>  lib/igt_kms.c   | 32 ++++++++++++++++++++++++++++++++
>  lib/igt_kms.h   |  1 +
>  tests/kms_vrr.c |  4 ++++
>  3 files changed, 37 insertions(+)
>
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index 6087de365..1bef7c124 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -6575,6 +6575,38 @@ bool igt_get_i915_edp_lobf_status(int drmfd, char *connector_name)
>  	return strstr(buf, "LOBF status: enabled");
>  }
>  
> +/**
> + * igt_is_aux_less_alpm_enabled
> + * @drmfd: A drm file descriptor
> + * @connector_name: Name of the libdrm connector we're going to use
> + *
> + * Check if Aux-less ALPM (Advanced Link Power Management) mode is enabled by reading
> + * the i915_edp_lobf_info debugfs.
> + *
> + * Return: True if aux-less ALPM is enabled.
> + */
> +bool igt_is_aux_less_alpm_enabled(int drmfd, char *connector_name)
> +{
> +	char buf[256];
char buf[256] = {0}; <- fell buf with zeros

> +	int fd, res;
> +
> +	fd = igt_debugfs_connector_dir(drmfd, connector_name, O_RDONLY);
> +	if (fd < 0)
> +		return false;
> +
> +	res = igt_debugfs_simple_read(fd, "i915_edp_lobf_info", buf, sizeof(buf));
/*and read n-1, so there is allways 0 at the end*/
res = igt_debugfs_simple_read(fd, "i915_edp_lobf_info", buf, sizeof(buf)-1);

> +	close(fd);
> +
> +	if (res <= 0) {
> +		igt_info("Failed to read i915_edp_lobf_info for %s\n", connector_name);
> +		return false;
> +	}
> +
> +	buf[res < sizeof(buf) ? res : sizeof(buf) - 1] = '\0';
That’s how I’d usually do it, but yours works too. Overall, it looks good to me.

Reviewed-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>


-- 
Best regards,
Sebastian