Re: [Intel-gfx] [RESEND 1/3] drm/i915/dsi: filter invalid backlight and CABC ports

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Tue, Aug 16, 2022 at 06:37:20PM +0300, Jani Nikula wrote:
> Avoid using ports that aren't initialized in case the VBT backlight or
> CABC ports have invalid values. This fixes a NULL pointer dereference of
> intel_dsi->dsi_hosts[port] in such cases.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>

Would be interesting to figure out which one of those actually fixed the
https://gitlab.freedesktop.org/drm/intel/-/issues/6476 issue, this one
or next one.

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> ---
>  drivers/gpu/drm/i915/display/icl_dsi.c | 7 +++++++
>  drivers/gpu/drm/i915/display/vlv_dsi.c | 7 +++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
> index 5dcfa7feffa9..885c74f60366 100644
> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
> @@ -2070,7 +2070,14 @@ void icl_dsi_init(struct drm_i915_private *dev_priv)
>  	else
>  		intel_dsi->ports = BIT(port);
>  
> +	if (drm_WARN_ON(&dev_priv->drm, intel_connector->panel.vbt.dsi.bl_ports & ~intel_dsi->ports))
> +		intel_connector->panel.vbt.dsi.bl_ports &= intel_dsi->ports;
> +
>  	intel_dsi->dcs_backlight_ports = intel_connector->panel.vbt.dsi.bl_ports;
> +
> +	if (drm_WARN_ON(&dev_priv->drm, intel_connector->panel.vbt.dsi.cabc_ports & ~intel_dsi->ports))
> +		intel_connector->panel.vbt.dsi.cabc_ports &= intel_dsi->ports;
> +
>  	intel_dsi->dcs_cabc_ports = intel_connector->panel.vbt.dsi.cabc_ports;
>  
>  	for_each_dsi_port(port, intel_dsi->ports) {
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
> index b9b1fed99874..35136d26e517 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
> @@ -1933,7 +1933,14 @@ void vlv_dsi_init(struct drm_i915_private *dev_priv)
>  	else
>  		intel_dsi->ports = BIT(port);
>  
> +	if (drm_WARN_ON(&dev_priv->drm, intel_connector->panel.vbt.dsi.bl_ports & ~intel_dsi->ports))
> +		intel_connector->panel.vbt.dsi.bl_ports &= intel_dsi->ports;
> +
>  	intel_dsi->dcs_backlight_ports = intel_connector->panel.vbt.dsi.bl_ports;
> +
> +	if (drm_WARN_ON(&dev_priv->drm, intel_connector->panel.vbt.dsi.cabc_ports & ~intel_dsi->ports))
> +		intel_connector->panel.vbt.dsi.cabc_ports &= intel_dsi->ports;
> +
>  	intel_dsi->dcs_cabc_ports = intel_connector->panel.vbt.dsi.cabc_ports;
>  
>  	/* Create a DSI host (and a device) for each port. */
> -- 
> 2.34.1
>