Re: [PATCH 2/8] drm/panel: do not return negative error codes from drm_panel_get_modes()

On 08/03/2024 17:03, Jani Nikula wrote:

None of the callers of drm_panel_get_modes() expect it to return negative error codes. Either they propagate the return value in their struct drm_connector_helper_funcs .get_modes() hook (which is also not supposed to return negative codes), or add it to other counts leading to bogus values.

On the other hand, many of the struct drm_panel_funcs .get_modes() hooks do return negative error codes, so handle them gracefully instead of propagating further.

Return 0 for no modes, whatever the reason.

Cc: Neil Armstrong neil.armstrong@linaro.org Cc: Jessica Zhang quic_jesszhan@quicinc.com Cc: Sam Ravnborg sam@ravnborg.org Cc: stable@vger.kernel.org Signed-off-by: Jani Nikula jani.nikula@intel.com

---

drivers/gpu/drm/drm_panel.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c index e814020bbcd3..cfbe020de54e 100644 --- a/drivers/gpu/drm/drm_panel.c +++ b/drivers/gpu/drm/drm_panel.c @@ -274,19 +274,24 @@ EXPORT_SYMBOL(drm_panel_disable);

• The modes probed from the panel are automatically added to the connector
• that the panel is attached to.

• • Return: The number of modes available from the panel on success or a
• • negative error code on failure.

• • Return: The number of modes available from the panel on success, or 0 on
• • failure (no modes).
  */ int drm_panel_get_modes(struct drm_panel *panel, struct drm_connector *connector) { if (!panel)

• return -EINVAL;
  

• return 0;
  

• if (panel->funcs && panel->funcs->get_modes)

• return panel->funcs->get_modes(panel, connector);
  

• if (panel->funcs && panel->funcs->get_modes) {

• int num;
  

• return -EOPNOTSUPP;

• num = panel->funcs->get_modes(panel, connector);
  

• if (num > 0)
  

• 	return num;
  

• }
• return 0; } EXPORT_SYMBOL(drm_panel_get_modes);

Reviewed-by: Neil Armstrong neil.armstrong@linaro.org