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* [PATCH 6.2 regression fix] drm/nouveau/kms: Fix backlight registration
@ 2023-03-26 20:54 Hans de Goede
  2023-03-28 22:23 ` Lyude Paul
  0 siblings, 1 reply; 3+ messages in thread
From: Hans de Goede @ 2023-03-26 20:54 UTC (permalink / raw)
  To: Ben Skeggs, Karol Herbst, Lyude Paul
  Cc: Hans de Goede, nouveau, dri-devel, regressions

The nouveau code used to call drm_fb_helper_initial_config() from
nouveau_fbcon_init() before calling drm_dev_register(). This would
probe all connectors so that drm_connector->status could be used during
backlight registration which runs from nouveau_connector_late_register().

After commit 4a16dd9d18a0 ("drm/nouveau/kms: switch to drm fbdev helpers")
the fbdev emulation code, which now is a drm-client, can only run after
drm_dev_register(). So during backlight registration the connectors are
not probed yet and the drm_connector->status == connected check in
nv50_backlight_init() would now always fail.

Replace the drm_connector->status == connected check with
a drm_helper_probe_detect() == connected check to fix nv_backlight
no longer getting registered because of this.

Fixes: 4a16dd9d18a0 ("drm/nouveau/kms: switch to drm fbdev helpers")
Link: https://gitlab.freedesktop.org/drm/nouveau/-/issues/202
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_backlight.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index 40409a29f5b6..91b5ecc57538 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -33,6 +33,7 @@
 #include <linux/apple-gmux.h>
 #include <linux/backlight.h>
 #include <linux/idr.h>
+#include <drm/drm_probe_helper.h>
 
 #include "nouveau_drv.h"
 #include "nouveau_reg.h"
@@ -299,8 +300,12 @@ nv50_backlight_init(struct nouveau_backlight *bl,
 	struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
 	struct nvif_object *device = &drm->client.device.object;
 
+	/*
+	 * Note when this runs the connectors have not been probed yet,
+	 * so nv_conn->base.status is not set yet.
+	 */
 	if (!nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(ffs(nv_encoder->dcb->or) - 1)) ||
-	    nv_conn->base.status != connector_status_connected)
+	    drm_helper_probe_detect(&nv_conn->base, NULL, false) != connector_status_connected)
 		return -ENODEV;
 
 	if (nv_conn->type == DCB_CONNECTOR_eDP) {
-- 
2.39.1


^ permalink raw reply related	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2023-03-29 10:34 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-03-26 20:54 [PATCH 6.2 regression fix] drm/nouveau/kms: Fix backlight registration Hans de Goede
2023-03-28 22:23 ` Lyude Paul
2023-03-29 10:34   ` Hans de Goede

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