media: imx: imx7-media-csi: Fix source type identification

The code in imx7_csi_pad_link_validate() that checks the type of the
source incorrectly handles devices that have no parallel input. In that
case, the source entity of the CSI is the CSI-2 receiver, not the video
mux, and the driver will proceed to check the type of the source of the
CSI-2 receiver.

Make the code more explicit to fix this, by handling the three cases
(parallel input only, CSI-2 receiver only, and video mux) separately.

Note that the driver will not correctly handle the case where only a
parallel input is present, and the external entity connected to the
parallel input reports a MEDIA_ENT_F_VID_IF_BRIDGE or
MEDIA_ENT_F_VID_MUX function. This was broken already, and should be
fixed separately.

Fixes: f5ffb81f5137 ("media: imx7: csi: Fix pad link validation")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/staging/media/imx/imx7-media-csi.c b/drivers/staging/media/imx/imx7-media-csi.c
index de7b933..2a4b69c 100644 (file)
--- a/drivers/staging/media/imx/imx7-media-csi.c
+++ b/drivers/staging/media/imx/imx7-media-csi.c
@@ -1000,39 +1000,47 @@ static int imx7_csi_pad_link_validate(struct v4l2_subdev *sd,
        struct imx7_csi *csi = v4l2_get_subdevdata(sd);
        struct imx_media_video_dev *vdev = csi->vdev;
        const struct v4l2_pix_format *out_pix = &vdev->fmt;
-       struct media_entity *src;
        struct media_pad *pad;
+       bool is_csi2;
        int ret;
 
+       if (!csi->src_sd)
+               return -EPIPE;
+
        /*
-        * Validate the source link, and record whether the CSI mux selects the
+        * Validate the source link, and record whether the source uses the
         * parallel input or the CSI-2 receiver.
         */
        ret = v4l2_subdev_link_validate_default(sd, link, source_fmt, sink_fmt);
        if (ret)
                return ret;
 
-       if (!csi->src_sd)
-               return -EPIPE;
+       switch (csi->src_sd->entity.function) {
+       case MEDIA_ENT_F_VID_IF_BRIDGE:
+               /* The input is the CSI-2 receiver. */
+               is_csi2 = true;
+               break;
 
-       src = &csi->src_sd->entity;
+       case MEDIA_ENT_F_VID_MUX:
+               /* The input is the mux, check its input. */
+               pad = imx_media_pipeline_pad(&csi->src_sd->entity, 0, 0, true);
+               if (!pad)
+                       return -ENODEV;
 
-       /*
-        * if the source is neither a CSI MUX or CSI-2 get the one directly
-        * upstream from this CSI
-        */
-       if (src->function != MEDIA_ENT_F_VID_IF_BRIDGE &&
-           src->function != MEDIA_ENT_F_VID_MUX)
-               src = &csi->sd.entity;
+               is_csi2 = pad->entity->function == MEDIA_ENT_F_VID_IF_BRIDGE;
+               break;
 
-       pad = imx_media_pipeline_pad(src, 0, 0, true);
-       if (!pad)
-               return -ENODEV;
+       default:
+               /*
+                * The input is an external entity, it must use the parallel
+                * bus.
+                */
+               is_csi2 = false;
+               break;
+       }
 
        mutex_lock(&csi->lock);
-
-       csi->is_csi2 = (pad->entity->function == MEDIA_ENT_F_VID_IF_BRIDGE);
-
+       csi->is_csi2 = is_csi2;
        mutex_unlock(&csi->lock);
 
        /* Validate the sink link, ensure the pixel format is supported. */