Re: [PATCH i-g-t v2 1/2] tests/kms_vrr: Start virtual RR test above midpoint to avoid mode fallback

["Reddy Guddati, Santhosh" <santhosh.reddy.guddati@intel.com>]

Hi Rama,

On 06-11-2025 10:17, Naladala Ramanaidu wrote:
> Starting from low_rr + step_size could cause the driver to fall back
> to a lower physical mode due to proximity to the lower bound of the
> VRR range. This results in an unintended clock change, which violates
> the expectation of seamless VRR behavior.
> 
> To address this, the test now starts from above the midpoint of the
> VRR range when multiple modes are available. This ensures the virtual
> refresh rate remains safely within the active mode's VRR range and
> avoids triggering a mode switch.
> 
> v2: Change logic to ternary operation. (Santhosh)
> 
> Signed-off-by: Naladala Ramanaidu <ramanaidu.naladala@intel.com>

LGTM,
Reviewed-by: Santhosh Reddy Guddati <santhosh.reddy.guddati@intel.com>
> ---
>   tests/kms_vrr.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/kms_vrr.c b/tests/kms_vrr.c
> index bcb756202..57691ccd5 100644
> --- a/tests/kms_vrr.c
> +++ b/tests/kms_vrr.c
> @@ -851,7 +851,16 @@ test_seamless_virtual_rr_basic(data_t *data, enum pipe pipe, igt_output_t *outpu
>   	/* Switch to Virtual RR */
>   	virtual_mode = *igt_output_get_mode(output);
>   
> -	for (vrefresh = data->range.min + step_size; vrefresh < data->range.max; vrefresh += step_size) {
> +	/*
> +	 * Start virtual RR testing from above the midpoint of the VRR range when multiple
> +	 * modes are available. This avoids the driver mode adjustment. which can cause an
> +	 * unintended clock change.
> +	 */
> +	vrefresh = (output->config.connector->count_modes > 1) ?
> +		   (((data->range.max + data->range.min) / 2) + step_size) :
> +		   data->range.min + step_size;
> +
> +	for ( ; vrefresh < data->range.max; vrefresh += step_size) {
>   		virtual_rr_vrr_range_mode(&virtual_mode, vrefresh);
>   
>   		igt_info("Requesting Virtual Mode with Refresh Rate (%u Hz): \n", vrefresh);