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SubjectRe: [PATCH v3 10/24] drm/sun4i: tcon: Generalize engine search algorithm
On Mon, Jun 25, 2018 at 8:02 PM, Jernej Skrabec <jernej.skrabec@siol.net> wrote:
> Current "old" method to find engine worked pretty well for DE2. However,
> it doesn't work when TCON TOP is between mixer (engine) and TCON. TCON
> TOP has multiple input ports, but current engine search algorithm
> expects only one.
>
> This can be fixed by first looking for output port id and selecting
> matching input by subtracting 1 for the next round. This work even if
> there is only one input and output.
>
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> ---
> drivers/gpu/drm/sun4i/sun4i_tcon.c | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index 08747fc3ee71..264bcc43da11 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -791,12 +791,14 @@ static int sun4i_tcon_init_regmap(struct device *dev,
> */
> static struct sunxi_engine *
> sun4i_tcon_find_engine_traverse(struct sun4i_drv *drv,
> - struct device_node *node)
> + struct device_node *node,
> + u32 port_id)
> {
> struct device_node *port, *ep, *remote;
> struct sunxi_engine *engine = ERR_PTR(-EINVAL);
> + u32 reg = 0;
>
> - port = of_graph_get_port_by_id(node, 0);
> + port = of_graph_get_port_by_id(node, port_id);
> if (!port)
> return ERR_PTR(-EINVAL);
>
> @@ -826,8 +828,20 @@ sun4i_tcon_find_engine_traverse(struct sun4i_drv *drv,
> if (remote == engine->node)
> goto out_put_remote;
>
> + /*
> + * According to device tree binding input ports have even id
> + * number and output ports have odd id. Since component with
> + * more than one input and one output (TCON TOP) exits, correct
> + * remote input id has to be calculated by subtracting 1 from
> + * remote output id. If this for some reason can't be done, 0
> + * is used as input port id.
> + */

You need to call

of_node_put(port);

to drop the reference to the original port.

Otherwise,

Reviewed-by: Chen-Yu Tsai <wens@csie.org>

> + port = of_graph_get_remote_port(ep);
> + if (!of_property_read_u32(port, "reg", &reg) && reg > 0)
> + reg -= 1;
> +
> /* keep looking through upstream ports */
> - engine = sun4i_tcon_find_engine_traverse(drv, remote);
> + engine = sun4i_tcon_find_engine_traverse(drv, remote, reg);
>
> out_put_remote:
> of_node_put(remote);
> @@ -950,7 +964,7 @@ static struct sunxi_engine *sun4i_tcon_find_engine(struct sun4i_drv *drv,
>
> /* Fallback to old method by traversing input endpoints */
> of_node_put(port);
> - return sun4i_tcon_find_engine_traverse(drv, node);
> + return sun4i_tcon_find_engine_traverse(drv, node, 0);
> }
>
> static int sun4i_tcon_bind(struct device *dev, struct device *master,
> --
> 2.18.0
>

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