diff options
Diffstat (limited to 'drivers/gpu/drm/sun4i/sun4i_backend.c')
| -rw-r--r-- | drivers/gpu/drm/sun4i/sun4i_backend.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c index e17e20036aa3..0b4222312e49 100644 --- a/drivers/gpu/drm/sun4i/sun4i_backend.c +++ b/drivers/gpu/drm/sun4i/sun4i_backend.c @@ -20,6 +20,7 @@ #include <linux/component.h> #include <linux/list.h> +#include <linux/of_graph.h> #include <linux/reset.h> #include "sun4i_backend.h" @@ -289,6 +290,45 @@ static int sun4i_backend_free_sat(struct device *dev) { return 0; } +/* + * The display backend can take video output from the display frontend, or + * the display enhancement unit on the A80, as input for one it its layers. + * This relationship within the display pipeline is encoded in the device + * tree with of_graph, and we use it here to figure out which backend, if + * there are 2 or more, we are currently probing. The number would be in + * the "reg" property of the upstream output port endpoint. + */ +static int sun4i_backend_of_get_id(struct device_node *node) +{ + struct device_node *port, *ep; + int ret = -EINVAL; + + /* input is port 0 */ + port = of_graph_get_port_by_id(node, 0); + if (!port) + return -EINVAL; + + /* try finding an upstream endpoint */ + for_each_available_child_of_node(port, ep) { + struct device_node *remote; + u32 reg; + + remote = of_parse_phandle(ep, "remote-endpoint", 0); + if (!remote) + continue; + + ret = of_property_read_u32(remote, "reg", ®); + if (ret) + continue; + + ret = reg; + } + + of_node_put(port); + + return ret; +} + static struct regmap_config sun4i_backend_regmap_config = { .reg_bits = 32, .val_bits = 32, @@ -312,6 +352,10 @@ static int sun4i_backend_bind(struct device *dev, struct device *master, return -ENOMEM; dev_set_drvdata(dev, backend); + backend->id = sun4i_backend_of_get_id(dev->of_node); + if (backend->id < 0) + return backend->id; + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); regs = devm_ioremap_resource(dev, res); if (IS_ERR(regs)) |