Re: [PATCH 1/4] drm/i915/gen9: Avoid using negative array index in skl_update_plane()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, May 12, 2016 at 04:18:49PM +0300, Imre Deak wrote:
> scaler_id may be negative as shown by conditions later in the function,
> so don't use it as an array index in that case.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_sprite.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
> index 0f3e230..286bcc6 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -203,8 +203,6 @@ skl_update_plane(struct drm_plane *drm_plane,
>  	uint32_t y = plane_state->src.y1 >> 16;
>  	uint32_t src_w = drm_rect_width(&plane_state->src) >> 16;
>  	uint32_t src_h = drm_rect_height(&plane_state->src) >> 16;
> -	const struct intel_scaler *scaler =
> -		&crtc_state->scaler_state.scalers[plane_state->scaler_id];
>  
>  	plane_ctl = PLANE_CTL_ENABLE |
>  		PLANE_CTL_PIPE_GAMMA_ENABLE |
> @@ -262,10 +260,14 @@ skl_update_plane(struct drm_plane *drm_plane,
>  	if (plane_state->scaler_id >= 0) {
>  		uint32_t ps_ctrl = 0;
>  		int scaler_id = plane_state->scaler_id;
> +		const struct intel_scaler *scaler;
>  
>  		DRM_DEBUG_KMS("plane = %d PS_PLANE_SEL(plane) = 0x%x\n", plane,
>  			PS_PLANE_SEL(plane));
> +
> +		scaler = &crtc_state->scaler_state.scalers[scaler_id];
>  		ps_ctrl = PS_SCALER_EN | PS_PLANE_SEL(plane) | scaler->mode;

Could nuke ps_ctrl while at it perhaps.

But in any case 
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
>  		I915_WRITE(SKL_PS_CTRL(pipe, scaler_id), ps_ctrl);
>  		I915_WRITE(SKL_PS_PWR_GATE(pipe, scaler_id), 0);
>  		I915_WRITE(SKL_PS_WIN_POS(pipe, scaler_id), (crtc_x << 16) | crtc_y);
> -- 
> 2.5.0
> 
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-- 
Ville Syrjälä
Intel OTC
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