Re: [PATCH] drm/panel: novatek-nt35950: Improve error handling

From: AngeloGioacchino Del Regno
Date: Mon Apr 17 2023 - 05:45:02 EST


Il 17/04/23 09:25, Neil Armstrong ha scritto:
On 15/04/2023 13:00, Konrad Dybcio wrote:
In a very peculiar case when probing and registering with the secondary
DSI host succeeds, but the OF backlight or DSI attachment fails, the
primary DSI device is automatically cleaned up, but the secondary one
is not, leading to -EEXIST when the driver core tries to handle
-EPROBE_DEFER.

Unregister the DSI1 device manually on failure to prevent that.

Fixes: 623a3531e9cf ("drm/panel: Add driver for Novatek NT35950 DSI DriverIC panels")
Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
---
  drivers/gpu/drm/panel/panel-novatek-nt35950.c | 8 +++++++-
  1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35950.c b/drivers/gpu/drm/panel/panel-novatek-nt35950.c
index abf752b36a52..7498fc6258bb 100644
--- a/drivers/gpu/drm/panel/panel-novatek-nt35950.c
+++ b/drivers/gpu/drm/panel/panel-novatek-nt35950.c
@@ -585,8 +585,11 @@ static int nt35950_probe(struct mipi_dsi_device *dsi)
                 DRM_MODE_CONNECTOR_DSI);
      ret = drm_panel_of_backlight(&nt->panel);
-    if (ret)
+    if (ret) {

If this is not a dual-DSI case, nt->dsi[1] will be NULL: I agree it's still
fine as in the kernel won't crash in that case, but for logical correctness
I would still account for that:

if (num_dsis == 2)
mipi_dsi_device_unregister(nt->dsi[1]);

+        mipi_dsi_device_unregister(nt->dsi[1]);
+
          return dev_err_probe(dev, ret, "Failed to get backlight\n");
+    }
      drm_panel_add(&nt->panel);
@@ -602,6 +605,9 @@ static int nt35950_probe(struct mipi_dsi_device *dsi)
          ret = mipi_dsi_attach(nt->dsi[i]);
          if (ret < 0) {

Same here, please add a check for num_dsis.

Regards,
Angelo