Re: [PATCH 4.19.y-cip 11/17] drm: of: Add drm_of_lvds_get_dual_link_pixel_order


Pavel Machek
 

Hi!

commit 6529007522ded00b8912c079250620fa7a732166 upstream.

An LVDS dual-link connection is made of two links, with even
pixels transitting on one link, and odd pixels on the other
link. The device tree can be used to fully describe dual-link
LVDS connections between encoders and bridges/panels.
The sink of an LVDS dual-link connection is made of two ports,
the corresponding OF graph port nodes can be marked
with either dual-lvds-even-pixels or dual-lvds-odd-pixels,
and that fully describes an LVDS dual-link connection,
including pixel order.
There is double-free bug here, AFAICT:

+ for_each_child_of_node(port_node, endpoint) {
+ struct device_node *remote_port;
+ int current_pt;
+
+ if (!of_node_name_eq(endpoint, "endpoint"))
+ continue;
+
+ remote_port = of_graph_get_remote_port(endpoint);
+ if (!remote_port) {
+ of_node_put(remote_port);
+ return -EPIPE;
+ }
+
+ current_pt = drm_of_lvds_get_port_pixels_type(remote_port);
+ of_node_put(remote_port);
You have put remote_port here.

+ if (pixels_type < 0)
+ pixels_type = current_pt;
+
+ /*
+ * Sanity check, ensure that all remote endpoints have the same
+ * pixel type. We may lift this restriction later if we need to
+ * support multiple sinks with different dual-link
+ * configurations by passing the endpoints explicitly to
+ * drm_of_lvds_get_dual_link_pixel_order().
+ */
+ if (!current_pt || pixels_type != current_pt) {
+ of_node_put(remote_port);
+ return -EINVAL;
And again here.

Now... it is only a problem in error path, so maybe easiest way is to
fix it in the mainline and then backport the fix here...

Best regards,

Pavel
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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