drm_mode_config_reset() has the expectation that drm_private_states are
not reset.

This is especially significant for the DP MST and tunneling code that
expect to be preserved across a suspend/resume cycle, where
drm_mode_config_reset() is also used.

Let's document this expectation.

Link: https://lore.kernel.org/dri-devel/aOaQLx-7EpsHRwkH@ideak-desk/
Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 drivers/gpu/drm/drm_mode_config.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 84ae8a23a36786705fea7c0eafd7f20813b7c8f9..54c27376f9894ef5eee378bb5b1e5fc7049de922 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -187,10 +187,14 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
  * @dev: drm device
  *
  * This functions calls all the crtc's, encoder's and connector's ->reset
  * callback. Drivers can use this in e.g. their driver load or resume code to
  * reset hardware and software state.
+ *
+ * It's worth noting that @drm_private_obj structures are expected to be
+ * stable across suspend/resume cycles, and @drm_mode_config_reset()
+ * will not affect these structures.
  */
 void drm_mode_config_reset(struct drm_device *dev)
 {
 	struct drm_crtc *crtc;
 	struct drm_colorop *colorop;

-- 
2.53.0

On Tue, Mar 10, 2026 at 05:06:55PM +0100, Maxime Ripard wrote:
> drm_mode_config_reset() has the expectation that drm_private_states are
> not reset.

I initially misinterpreted that. I don't think it's an "expectation".
The function simply does not reset the private objects states. If you
want to keep "expectation", you can write

drm_mode_config_reset() has the expectation that drm_private_states do
not need to be reset.

> This is especially significant for the DP MST and tunneling code that
> expect to be preserved across a suspend/resume cycle, where
> drm_mode_config_reset() is also used.
> 
> Let's document this expectation.
> 
> Link: https://lore.kernel.org/dri-devel/aOaQLx-7EpsHRwkH@ideak-desk/
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
> ---
>  drivers/gpu/drm/drm_mode_config.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 84ae8a23a36786705fea7c0eafd7f20813b7c8f9..54c27376f9894ef5eee378bb5b1e5fc7049de922 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -187,10 +187,14 @@ int drm_mode_getresources(struct drm_device *dev, void *data,
>   * @dev: drm device
>   *
>   * This functions calls all the crtc's, encoder's and connector's ->reset
>   * callback. Drivers can use this in e.g. their driver load or resume code to
>   * reset hardware and software state.
> + *
> + * It's worth noting that @drm_private_obj structures are expected to be

s/It's worth noting/Note/

> + * stable across suspend/resume cycles, and @drm_mode_config_reset()
> + * will not affect these structures.

s/will/does/

With this addressed,

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

>   */
>  void drm_mode_config_reset(struct drm_device *dev)
>  {
>  	struct drm_crtc *crtc;
>  	struct drm_colorop *colorop;
> 

-- 
Regards,

Laurent Pinchart