[PATCH i-g-t v1] tests/kms_vblank: Skip timing check in simulation to avoid false negatives

[Sharma, Swati2]

Hi Ramanaidu,

Patch LGTM.
Reviewed-by: Swati Sharma <swati2.sharma at intel.com>

On 11-07-2025 11:37 pm, Naladala Ramanaidu wrote:
> Simulation environments often do not reflect real hardware timing
> accurately, which can result in false negatives during vblank
> sequence testing. To prevent such issues, this patch conditionally
> skips the timing  validation when the test run in simulation.
>
> Signed-off-by: Naladala Ramanaidu <ramanaidu.naladala at intel.com>
> ---
>   tests/kms_vblank.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tests/kms_vblank.c b/tests/kms_vblank.c
> index b8044ad42..75cf9448f 100644
> --- a/tests/kms_vblank.c
> +++ b/tests/kms_vblank.c
> @@ -460,8 +460,17 @@ static void vblank_ts_cont(data_t *data, int fd, int nchildren)
>   
>   	igt_assert_f(seq2 - seq1 >= 0, "elapsed %f(%d vblanks) unexpected vblank seq %u, should be > %u\n", time_elapsed,
>   			estimated_vblanks, seq2, seq1);
> -	igt_assert_f(seq2 - seq1 <= estimated_vblanks + VBLANK_ERR, "elapsed %f(%d vblanks) unexpected vblank seq %u, should be <= %u\n", time_elapsed,
> -			estimated_vblanks, seq2, seq1 + estimated_vblanks);
> +	/*
> +	 * Timing behavior in simulation environments often differs from real hardware,
> +	 * which can lead to false negatives during testing. To mitigate this, disable
> +	 * timestamp and sequence validations when the INTEL_SIMULATION environment
> +	 * variable is active.
> +	 */
> +	if (!igt_run_in_simulation())
> +		igt_assert_f(seq2 - seq1 <= estimated_vblanks + VBLANK_ERR,
> +			     "elapsed %f(%d vblanks) unexpected vblank seq %u, should be <= %u\n",
> +			     time_elapsed, estimated_vblanks,
> +			     seq2, seq1 + estimated_vblanks);
>   }
>   
>   static void run_subtests(data_t *data)