My Samsung N210 has a VBT with DEVICE_TYPE_INT_LFP with a zero addin-offset. With the check in place, the panel was declared absent.
v2: Only trust BIOS writers that have graduated to writing OpRegions. (We are all doomed.) Signed-off-by: Chris Wilson <[email protected]> Cc: Zhao Yakui <[email protected]> Cc: Adam Jackson <[email protected]> --- drivers/gpu/drm/i915/intel_lvds.c | 46 +++++++++++++++++++++---------------- 1 files changed, 26 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c index c9b62fe..56a3e65 100644 --- a/drivers/gpu/drm/i915/intel_lvds.c +++ b/drivers/gpu/drm/i915/intel_lvds.c @@ -777,38 +777,44 @@ static void intel_find_lvds_downclock(struct drm_device *dev, * If it is present, return 1. * If it is not present, return false. * If no child dev is parsed from VBT, it assumes that the LVDS is present. - * Note: The addin_offset should also be checked for LVDS panel. - * Only when it is non-zero, it is assumed that it is present. */ -static int lvds_is_present_in_vbt(struct drm_device *dev) +static bool lvds_is_present_in_vbt(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; - struct child_device_config *p_child; - int i, ret; + int i; if (!dev_priv->child_dev_num) - return 1; + return true; - ret = 0; for (i = 0; i < dev_priv->child_dev_num; i++) { - p_child = dev_priv->child_dev + i; - /* - * If the device type is not LFP, continue. - * If the device type is 0x22, it is also regarded as LFP. + struct child_device_config *child = dev_priv->child_dev + i; + + /* If the device type is not LFP, continue. + * We have to check both the new identifiers as well as the + * old for compatibility with some BIOSes. */ - if (p_child->device_type != DEVICE_TYPE_INT_LFP && - p_child->device_type != DEVICE_TYPE_LFP) + if (child->device_type != DEVICE_TYPE_INT_LFP && + child->device_type != DEVICE_TYPE_LFP) continue; - /* The addin_offset should be checked. Only when it is - * non-zero, it is regarded as present. + /* However, we cannot trust the BIOS writers to populate + * the VBT correctly. Since LVDS requires additional + * information from AIM blocks, a non-zero addin offset is + * a good indicator that the LVDS is actually present. */ - if (p_child->addin_offset) { - ret = 1; - break; - } + if (child->addin_offset) + return true; + + /* But even then some BIOS writers perform some black magic + * and instantiate the device without reference to any + * additional data. Trust that if the VBT was written into + * the OpRegion then they have validated the LVDS's existence. + */ + if (dev_priv->opregion.vbt) + return true; } - return ret; + + return false; } /** -- 1.7.1 _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
