[Intel-gfx] [PATCH 1/4] drm/dp_mst: Don't report ports connected if nothing is attached to them

[Imre Deak]

On Mon, Feb 01, 2021 at 02:01:42PM +0200, Imre Deak wrote:
> Reporting a port as connected if nothing is attached to them leads to
> any i2c transactions on this port trying to use an uninitialized i2c
> adapter, fix this.
> 
> Let's account for this case even if branch devices have no good reason
> to report a port as unplugged with their peer device type set to 'none'.
> 
> Fixes: db1a07956968 ("drm/dp_mst: Handle SST-only branch device case")
> References: https://gitlab.freedesktop.org/drm/intel/-/issues/2987
> References: https://gitlab.freedesktop.org/drm/intel/-/issues/1963
> Cc: Wayne Lin <Wayne.Lin at amd.com>
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: <stable at vger.kernel.org> # v5.5+
> Cc: intel-gfx at lists.freedesktop.org
> Signed-off-by: Imre Deak <imre.deak at intel.com>

Thanks for the report and review, I pushed this one patch to
drm-misc-fixes.

I fixed a typo in the commit message.

> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index e82b596d646c..deb7995f42fa 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -4224,6 +4224,7 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
>  
>  	switch (port->pdt) {
>  	case DP_PEER_DEVICE_NONE:
> +		break;
>  	case DP_PEER_DEVICE_MST_BRANCHING:
>  		if (!port->mcs)
>  			ret = connector_status_connected;
> -- 
> 2.25.1
> 
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