@@ -63,7 +63,7 @@ struct i915_params i915 __read_mostly = {
.huc_firmware_path = NULL,
.enable_dp_mst = true,
.inject_load_failure = 0,
- .enable_dpcd_backlight = -1,
+ .enable_dpcd_backlight = false,
.enable_gvt = false,
.enable_dbc = true,
};
@@ -247,10 +247,9 @@ MODULE_PARM_DESC(enable_dp_mst,
module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
MODULE_PARM_DESC(inject_load_failure,
"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
-module_param_named_unsafe(enable_dpcd_backlight, i915.enable_dpcd_backlight, int, 0600);
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
MODULE_PARM_DESC(enable_dpcd_backlight,
- "Enable support for DPCD backlight control "
- "(-1:auto (default), 0:force disable, 1:force enabled if supported");
+ "Enable support for DPCD backlight control (default:false)");
module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
MODULE_PARM_DESC(enable_gvt,
@@ -53,7 +53,6 @@
func(int, edp_vswing); \
func(int, reset); \
func(unsigned int, inject_load_failure); \
- func(int, enable_dpcd_backlight); \
/* leave bools at the end to not create holes */ \
func(bool, alpha_support); \
func(bool, enable_cmd_parser); \
@@ -277,66 +277,15 @@ intel_dp_aux_display_control_capable(struct intel_connector *connector)
/* Check the eDP Display control capabilities registers to determine if
* the panel can support backlight control over the aux channel
*/
- if ((intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP) &&
- (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP)) {
+ if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+ (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_AUX_SET_CAP) &&
+ !(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP)) {
DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
return true;
}
return false;
}
-/*
- * Heuristic function whether we should use AUX for backlight adjustment or not.
- *
- * We should use AUX for backlight brightness adjustment if panel doesn't this
- * via PWM pin or using AUX is better than using PWM pin.
- *
- * The heuristic to determine that using AUX pin is better than using PWM pin is
- * that the panel support any of the feature list here.
- * - Regional backlight brightness adjustment
- * - Backlight PWM frequency set
- * - More than 8 bits resolution of brightness level
- * - Backlight enablement via AUX and not by BL_ENABLE pin
- *
- * If all above are not true, assume that using PWM pin is better.
- */
-static bool
-intel_dp_aux_display_control_heuristic(struct intel_connector *connector)
-{
- struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
- uint8_t reg_val;
-
- /* Panel doesn't support adjusting backlight brightness via PWN pin */
- if (!(intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))
- return true;
-
- /* Panel supports regional backlight brightness adjustment */
- if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_GENERAL_CAP_3,
- ®_val) != 1) {
- DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
- DP_EDP_GENERAL_CAP_3);
- return false;
- }
- if (reg_val > 0)
- return true;
-
- /* Panel supports backlight PWM frequency set */
- if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP)
- return true;
-
- /* Panel supports more than 8 bits resolution of brightness level */
- if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
- return true;
-
- /* Panel supports enabling backlight via AUX but not by BL_ENABLE pin */
- if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
- !(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP))
- return true;
-
- return false;
-
-}
-
int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
{
struct intel_panel *panel = &intel_connector->panel;
@@ -347,10 +296,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
if (!intel_dp_aux_display_control_capable(intel_connector))
return -ENODEV;
- if (i915.enable_dpcd_backlight == -1 &&
- !intel_dp_aux_display_control_heuristic(intel_connector))
- return -ENODEV;
-
panel->backlight.setup = intel_dp_aux_setup_backlight;
panel->backlight.enable = intel_dp_aux_enable_backlight;
panel->backlight.disable = intel_dp_aux_disable_backlight;
This reverts commit 560a758d39c616f83ac25ff6e0816a49ebe6401c. This patch has been identified to introduce a backlight regression on at least two different platforms; either the heuristic is broken (if so the patch needs to be reworked) or the in-kernel DPCD backlight support is broken (if so it's premature to enable DPCD backlight even if the platforms support it). Signed-off-by: David Weinehall <david.weinehall@linux.intel.com> --- drivers/gpu/drm/i915/i915_params.c | 7 ++- drivers/gpu/drm/i915/i915_params.h | 1 - drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 61 ++------------------------- 3 files changed, 6 insertions(+), 63 deletions(-)