[PATCH] drm:bridge:analogix: Fix refcount bugs in anx7625_parse_dt()

[Liang He]

At 2022-07-18 19:54:18, "Robert Foss" <robert.foss at linaro.org> wrote:
>Hey Liang,
>
>
>On Thu, 7 Jul 2022 at 03:25, Liang He <windhl at 126.com> wrote:
>>
>> There are two refcount bugs in this funcion:
>>
>> BUG-1: 'pdata->mipi_host_node' will be assigned a new reference with
>> of_graph_get_remote_node() which will increase the refcount of the
>> object, correspondingly, we should call of_node_put() for the old
>> reference stored in the 'pdata->mipi_host_node'.
>>
>> BUG-2: of_graph_get_endpoint_by_regs() will also increase the refcount
>> of the object and its new reference will be assigned to local 'ep0', so
>> there should be a of_node_put() when 'ep0' is not used anymore.
>>
>> Fixes: 8bdfc5dae4e3 ("drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to DP")
>> Fixes: fd0310b6fe7d ("drm/bridge: anx7625: add MIPI DPI input feature")
>> Signed-off-by: Liang He <windhl at 126.com>
>> ---
>>  drivers/gpu/drm/bridge/analogix/anx7625.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
>> index 53a5da6c49dd..f39b9be19eaf 100644
>> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
>> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
>> @@ -1624,6 +1624,7 @@ static int anx7625_parse_dt(struct device *dev,
>>         anx7625_get_swing_setting(dev, pdata);
>>
>>         pdata->is_dpi = 1; /* default dpi mode */
>> +       of_node_put(pdata->mipi_host_node);
>>         pdata->mipi_host_node = of_graph_get_remote_node(np, 0, 0);
>>         if (!pdata->mipi_host_node) {
>>                 DRM_DEV_ERROR(dev, "fail to get internal panel.\n");
>> @@ -1638,6 +1639,7 @@ static int anx7625_parse_dt(struct device *dev,
>>                         bus_type = 0;
>>
>>                 mipi_lanes = of_property_count_u32_elems(ep0, "data-lanes");
>> +               of_node_put(ep0);
>>         }
>>
>>         if (bus_type == V4L2_FWNODE_BUS_TYPE_PARALLEL) /* bus type is Parallel(DSI) */
>> --
>> 2.25.1
>>
>
>This patch does not apply on drm-misc-next, could you please rebase it
>and send a v2?
>
>Rob.

Thanks for your reply.

I will rebase it soon.

Liang