From: Jani Nikula <jani.nikula@intel.com>
To: intel-gfx@lists.freedesktop.org
Cc: jani.nikula@intel.com
Subject: [Intel-gfx] [PATCH 2/2] drm/i915/backlight: use unique backlight device names
Date: Wed, 28 Apr 2021 13:14:29 +0300 [thread overview]
Message-ID: <7dc3f6974711ce44522189dc9db05d1e6e24e6d8.1619604743.git.jani.nikula@intel.com> (raw)
In-Reply-To: <cover.1619604743.git.jani.nikula@intel.com>
Registering multiple backlight devices with intel_backlight name will
obviously fail, regardless of whether they're two connectors in the same
drm device or two different drm devices.
It would be preferrable to switch to completely unique names, and sunset
the generic intel_backlight name. However, there are apparently users
out there that hardcode the name, so the change would break backward
compatibility.
As a compromise, register the first device with intel_backlight name. In
the common case, this is the only backlight device anyway. From the
second device on, use card%d-%s-backlight format, for example
card0-eDP-2-backlight, to make the name unique.
This approach does not preclude us from registering the first device
using the same naming scheme in the future.
v2: Keep using intel_backlight name for first backlight device
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2794
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/i915/display/intel_panel.c | 23 ++++++++++++++++++----
1 file changed, 19 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 3088677ab8a7..a20761079ae0 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -1401,16 +1401,31 @@ int intel_backlight_device_register(struct intel_connector *connector)
else
props.power = FB_BLANK_POWERDOWN;
- /*
- * Note: using the same name independent of the connector prevents
- * registration of multiple backlight devices in the driver.
- */
name = kstrdup("intel_backlight", GFP_KERNEL);
if (!name)
return -ENOMEM;
bd = backlight_device_register(name, connector->base.kdev, connector,
&intel_backlight_device_ops, &props);
+
+ /*
+ * Using the same name independent of the drm device or connector
+ * prevents registration of multiple backlight devices in the
+ * driver. However, we need to use the default name for backward
+ * compatibility. Use unique names for subsequent backlight devices as a
+ * fallback when the default name already exists.
+ */
+ if (IS_ERR(bd) && PTR_ERR(bd) == -EEXIST) {
+ kfree(name);
+ name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",
+ i915->drm.primary->index, connector->base.name);
+ if (!name)
+ return -ENOMEM;
+
+ bd = backlight_device_register(name, connector->base.kdev, connector,
+ &intel_backlight_device_ops, &props);
+ }
+
if (IS_ERR(bd)) {
drm_err(&i915->drm,
"[CONNECTOR:%d:%s] backlight device %s register failed: %ld\n",
--
2.20.1
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next prev parent reply other threads:[~2021-04-28 10:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 10:14 [Intel-gfx] [PATCH 0/2] drm/i915/backlight: use unique backlight device names Jani Nikula
2021-04-28 10:14 ` [Intel-gfx] [PATCH 1/2] drm/i915/backlight: clean up backlight device register Jani Nikula
2021-04-28 10:14 ` Jani Nikula [this message]
2021-04-28 12:01 ` [Intel-gfx] [PATCH 2/2] drm/i915/backlight: use unique backlight device names Ville Syrjälä
2021-04-28 12:06 ` Jani Nikula
2021-04-28 11:19 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2021-04-28 12:45 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2021-04-29 13:28 ` [Intel-gfx] ✓ Fi.CI.BAT: success for drm/i915/backlight: use unique backlight device names (rev2) Patchwork
2021-04-29 16:11 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
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