From 53ca2edcf033f3368b2dc0ef3cbcc2f47d556d13 Mon Sep 17 00:00:00 2001 From: "Lee, Shawn C" Date: Tue, 11 Sep 2018 23:22:50 -0700 Subject: drm: Change limited M/N quirk to constant N quirk. Some DP dongles in particular seem to be fussy about too large link M/N values. Set specific value for N divider can resolve this issue per dongle vendor's comment. So configure N as constant value (0x8000) to instead of reduce M/N formula when specific DP dongle connected. v2: add more comments for issue description and fix typo. v3: add lost commit messages back for version 2 v4: send patch to both intel-gfx and dri-devel Cc: Jani Nikula Cc: Cooper Chiou Cc: Matt Atwood Cc: Maarten Lankhorst Cc: Dhinakaran Pandiyan Cc: Clint Taylor Tested-by: Clint Taylor Signed-off-by: Lee, Shawn C Signed-off-by: Jani Nikula Link: https://patchwork.freedesktop.org/patch/msgid/1536733371-25004-3-git-send-email-shawn.c.lee@intel.com --- include/drm/drm_dp_helper.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/drm') diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h index 698082a02b97..2a3843f248cf 100644 --- a/include/drm/drm_dp_helper.h +++ b/include/drm/drm_dp_helper.h @@ -1261,12 +1261,12 @@ int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc, */ enum drm_dp_quirk { /** - * @DP_DPCD_QUIRK_LIMITED_M_N: + * @DP_DPCD_QUIRK_CONSTANT_N: * * The device requires main link attributes Mvid and Nvid to be limited - * to 16 bits. + * to 16 bits. So will give a constant value (0x8000) for compatability. */ - DP_DPCD_QUIRK_LIMITED_M_N, + DP_DPCD_QUIRK_CONSTANT_N, }; /** -- cgit v1.2.3