Re: [PATCH v4 10/27] drm/bridge: ti-sn65dsi86: Clean debugfs code

Bjorn Andersson
2021-04-23T14:35:47Z

On Fri 16 Apr 17:39 CDT 2021, Douglas Anderson wrote:

> Let's cleanup the debugfs code to:
> - Check for errors.
> - Use devm to manage freeing, which also means we don't need to store
> a pointer in our structure.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
> (no changes since v1)
>
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 32 +++++++++++++++++----------
> 1 file changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 57574132e200..0c6aa99ddc99 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -118,7 +118,6 @@
> * @aux: Our aux channel.
> * @bridge: Our bridge.
> * @connector: Our connector.
> - * @debugfs: Used for managing our debugfs.
> * @host_node: Remote DSI node.
> * @dsi: Our MIPI DSI source.
> * @edid: Detected EDID of eDP panel.
> @@ -146,7 +145,6 @@ struct ti_sn65dsi86 {
> struct drm_dp_aux aux;
> struct drm_bridge bridge;
> struct drm_connector connector;
> - struct dentry *debugfs;
> struct edid *edid;
> struct device_node *host_node;
> struct mipi_dsi_device *dsi;
> @@ -245,18 +243,30 @@ static int status_show(struct seq_file *s, void *data)
>
> DEFINE_SHOW_ATTRIBUTE(status);
>
> -static void ti_sn65dsi86_debugfs_init(struct ti_sn65dsi86 *pdata)
> +static void ti_sn65dsi86_debugfs_remove(void *data)
> {
> - pdata->debugfs = debugfs_create_dir(dev_name(pdata->dev), NULL);
> -
> - debugfs_create_file("status", 0600, pdata->debugfs, pdata,
> - &status_fops);
> + debugfs_remove_recursive(data);
> }
>
> -static void ti_sn65dsi86_debugfs_remove(struct ti_sn65dsi86 *pdata)
> +static void ti_sn65dsi86_debugfs_init(struct ti_sn65dsi86 *pdata)
> {
> - debugfs_remove_recursive(pdata->debugfs);
> - pdata->debugfs = NULL;
> + struct device *dev = pdata->dev;
> + struct dentry *debugfs;
> + int ret;
> +
> + debugfs = debugfs_create_dir(dev_name(dev), NULL);
> + if (IS_ERR(debugfs))
> + ret = PTR_ERR(debugfs);
> + else
> + ret = devm_add_action_or_reset(dev, ti_sn65dsi86_debugfs_remove,
> + debugfs);
> +
> + if (ret) {

You're not supposed to handle errors from debugfs_create_dir(), but I
like what you're doing with devm here and that needs a check.

Also worth mentioning is that at this point in the patch stack the
debugfs "status" file will outlive the activation of pm_runtime, this is
however taken care of in a later patch. Given that it's unlikely to
cause a problem I don't mind this transient issue - but wanted to
mention that I reviewed the end result in this regard.

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> + dev_warn(dev, "Failed to create debugfs (%d), skipping\n", ret);
> + return;
> + }
> +
> + debugfs_create_file("status", 0600, debugfs, pdata, &status_fops);
> }
>
> /* Connector funcs */
> @@ -1310,8 +1320,6 @@ static int ti_sn65dsi86_remove(struct i2c_client *client)
>
> kfree(pdata->edid);
>
> - ti_sn65dsi86_debugfs_remove(pdata);
> -
> drm_bridge_remove(&pdata->bridge);
>
> pm_runtime_disable(pdata->dev);
> --
> 2.31.1.368.gbe11c130af-goog
>