From cf2bc7c504b0ab30ce37893a9900e4dd8fe3e6ae Mon Sep 17 00:00:00 2001
From: Lyude Paul <lyude@redhat.com>
Date: Fri, 4 Feb 2022 13:05:04 -0500
Subject: drm/nouveau/backlight: Fix LVDS backlight detection on some laptops
Git-commit: 6b0076540faffd47f5a899bf12f3528c4f0e726b
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
It seems that some laptops will report having both an eDP and LVDS
connector, even though only the LVDS connector is actually hooked up. This
can lead to issues with backlight registration if the eDP connector ends up
getting registered before the LVDS connector, as the backlight device will
then be registered to the eDP connector instead of the LVDS connector.
So, fix this by only registering the backlight on connectors that are
reported as being connected.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Fixes: 6eca310e8924 ("drm/nouveau/kms/nv50-: Add basic DPCD backlight support for nouveau")
Bugzilla: https://gitlab.freedesktop.org/drm/nouveau/-/issues/137
Cc: <stable@vger.kernel.org> # v5.15+
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220204180504.328999-1-lyude@redhat.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/nouveau/nouveau_backlight.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index ae2f2abc8f5a..6af12dc99d7f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -294,7 +294,8 @@ 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;
- if (!nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(ffs(nv_encoder->dcb->or) - 1)))
+ if (!nvif_rd32(device, NV50_PDISP_SOR_PWM_CTL(ffs(nv_encoder->dcb->or) - 1)) ||
+ nv_conn->base.status != connector_status_connected)
return -ENODEV;
if (nv_conn->type == DCB_CONNECTOR_eDP) {
--
2.38.1