Re: [v6,3/4] drm/i915/display: harden shift in intel_ddi_compute_config_late()

["Michał Grzelak" <michal.grzelak@intel.com>]

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On Tue, 9 Jun 2026, Luca Coelho wrote:
> BIT() takes a non-negative shift amount, but cpu_transcoder is of type
> enum transcoder, which can in theory be INVALID_TRANSCODER (-1).
>
> This is not a problem with the current implementation, because
> cpu_transcoder is always valid when this code is reached, but it's
> more robust to cast to unsigned so the shift is always well-defined.
>
> Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 6399b16405c8..51816c5bc80b 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -4635,8 +4635,8 @@ static int intel_ddi_compute_config_late(struct intel_encoder *encoder,
>
> 	if (crtc_state->master_transcoder == crtc_state->cpu_transcoder) {
> 		crtc_state->master_transcoder = INVALID_TRANSCODER;
> -		crtc_state->sync_mode_slaves_mask =
> -			port_sync_transcoders & ~BIT(crtc_state->cpu_transcoder);
> +		crtc_state->sync_mode_slaves_mask = port_sync_transcoders &
> +			~REG_BIT(crtc_state->cpu_transcoder);

Reviewed-by: Michał Grzelak <michal.grzelak@intel.com>

BR,
Michał

> 	}
>
> 	return 0;
>