Re: [PATCH v13 2/2] drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to DP

From: Nicolas Boichat
Date: Tue Jul 07 2020 - 03:01:40 EST


On Tue, Jun 9, 2020 at 3:20 PM Xin Ji <xji@xxxxxxxxxxxxxxxx> wrote:
>
> The ANX7625 is an ultra-low power 4K Mobile HD Transmitter designed
> for portable device. It converts MIPI DSI/DPI to DisplayPort 1.3 4K.
>
> Signed-off-by: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/bridge/analogix/Kconfig | 9 +
> drivers/gpu/drm/bridge/analogix/Makefile | 1 +
> drivers/gpu/drm/bridge/analogix/anx7625.c | 1999 +++++++++++++++++++++++++++++
> drivers/gpu/drm/bridge/analogix/anx7625.h | 397 ++++++
> 4 files changed, 2406 insertions(+)
> create mode 100644 drivers/gpu/drm/bridge/analogix/anx7625.c
> create mode 100644 drivers/gpu/drm/bridge/analogix/anx7625.h
>
> [snip]
> +static int anx7625_parse_dt(struct device *dev,
> + struct anx7625_platform_data *pdata)
> +{
> + struct device_node *np = dev->of_node;
> + struct device_node *panel_node, *out_ep;
> +
> + pdata->node.mipi_dsi_host_node = of_graph_get_remote_node(np, 0, 0);
> + if (!pdata->node.mipi_dsi_host_node) {
> + DRM_DEV_ERROR(dev, "fail to get internal panel.\n");
> + return -EPROBE_DEFER;

This does not look correct. I don't think of_graph_get_remote_node
will ever return NULL if the device tree is configured properly, and
it's useless to retry later (EPROBE_DEFER). You should just fail (e.g.
return EINVAL).

> + }
> +
> + of_node_put(pdata->node.mipi_dsi_host_node);

You are using pdata->node.mipi_dsi_host_node in other places in the
code, so I don't think it's ok to call of_node_put?

> + DRM_DEV_DEBUG_DRIVER(dev, "found dsi host node.\n");
> +
> + pdata->node.panel_node = of_graph_get_port_by_id(np, 1);
> + if (!pdata->node.panel_node) {
> + DRM_DEV_ERROR(dev, "fail to get panel node.\n");
> + return -EPROBE_DEFER;

-EINVAL.

> + }
> +
> + of_node_put(pdata->node.panel_node);
> + out_ep = of_get_child_by_name(pdata->node.panel_node,
> + "endpoint");
> + if (!out_ep) {
> + DRM_DEV_DEBUG_DRIVER(dev, "cannot get endpoint.\n");

DRM_DEV_ERROR seems more appropriate

> + return -EPROBE_DEFER;

-EINVAL

> + }
> +
> + panel_node = of_graph_get_remote_port_parent(out_ep);
> + of_node_put(out_ep);
> + pdata->panel = of_drm_find_panel(panel_node);
> + DRM_DEV_DEBUG_DRIVER(dev, "get panel node.\n");
> +
> + of_node_put(panel_node);
> + if (IS_ERR_OR_NULL(pdata->panel))
> + return -EPROBE_DEFER;

of_drm_find_panel cannot return NULL, so, do this instead:

if (IS_ERR(pdata->panel))
return PTR_ERR(pdata->panel);

(which actually _may_ return EPROBE_DEFER)

> +
> + return 0;
> +}
> [snip]
> +static int anx7625_i2c_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct anx7625_data *platform;
> + struct anx7625_platform_data *pdata;
> + int ret = 0;
> + struct device *dev = &client->dev;
> +
> + if (!i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_I2C_BLOCK)) {
> + DRM_DEV_ERROR(dev, "anx7625's i2c bus doesn't support\n");
> + return -ENODEV;
> + }
> +
> + platform = kzalloc(sizeof(*platform), GFP_KERNEL);
> + if (!platform) {
> + DRM_DEV_ERROR(dev, "fail to allocate driver data\n");
> + return -ENOMEM;
> + }
> +
> + pdata = &platform->pdata;
> +
> + ret = anx7625_parse_dt(dev, pdata);
> + if (ret) {
> + DRM_DEV_ERROR(dev, "fail to parse devicetree.\n");

Please do not print this error (or at least not if err == -EPROBE_DEFER).

> + goto free_platform;
> + }