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authorTakashi Iwai <tiwai@suse.de>2017-01-09 15:56:14 +0100
committerVille Syrjälä <ville.syrjala@linux.intel.com>2017-01-11 18:46:07 +0200
commitfdf35a6b22247746a7053fc764d04218a9306f82 (patch)
tree90e11a2b7455c3718600f46cb712f1dfe21c3f54 /drivers/gpu/drm/drm_modes.c
parent68f458eec7069d618a6c884ca007426e0cea411b (diff)
downloadlinux-fdf35a6b22247746a7053fc764d04218a9306f82.tar.bz2
drm: Fix broken VT switch with video=1366x768 option
I noticed that the VT switch doesn't work any longer with a Dell laptop with 1366x768 eDP when the machine is connected with a DP monitor. It behaves as if VT were switched, but the graphics remain frozen. Actually the keyboard works, so I could switch back to VT7 again. I tried to track down the problem, and encountered a long story until we reach to this error: - The machine is booted with video=1366x768 option (the distro installer seems to add it as default). - Recently, drm_helper_probe_single_connector_modes() deals with cmdline modes, and it tries to create a new mode when no matching mode is found. - The drm_mode_create_from_cmdline_mode() creates a mode based on either CVT of GFT according to the given cmdline mode; in our case, it's 1366x768. - Since both CVT and GFT can't express the width 1366 due to alignment, the resultant mode becomes 1368x768, slightly larger than the given size. - Later on, the atomic commit is performed, and in drm_atomic_check_only(), the size of each plane is checked. - The size check of 1366x768 fails due to the above, and eventually the whole VT switch fails. Back in the history, we've had a manual fix-up of 1368x768 in various places via c09dedb7a50e ("drm/edid: Add a workaround for 1366x768 HD panel"), but they have been all in drm_edid.c at probing the modes from EDID. For addressing the problem above, we need a similar hack to the mode newly created from cmdline, manually adjusting the width when the expected size is 1366 while we get 1368 instead. Fixes: eaf99c749d43 ("drm: Perform cmdline mode parsing during...") Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Link: http://patchwork.freedesktop.org/patch/msgid/20170109145614.29454-1-tiwai@suse.de Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Diffstat (limited to 'drivers/gpu/drm/drm_modes.c')
-rw-r--r--drivers/gpu/drm/drm_modes.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index ac6a35212501..e6b19bc9021a 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1460,6 +1460,13 @@ drm_mode_create_from_cmdline_mode(struct drm_device *dev,
return NULL;
mode->type |= DRM_MODE_TYPE_USERDEF;
+ /* fix up 1368x768: GFT/CVT can't express 1366 width due to alignment */
+ if (cmd->xres == 1366 && mode->hdisplay == 1368) {
+ mode->hdisplay = 1366;
+ mode->hsync_start--;
+ mode->hsync_end--;
+ drm_mode_set_name(mode);
+ }
drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
return mode;
}