[Intel-gfx] [PATCH 25/26] drm/i915: remove in_dbg_master check from intel_fbc.c

Paulo Zanoni paulo.r.zanoni at intel.com
Tue Oct 27 09:50:27 PDT 2015

>From our maintainer Daniel Vetter a few days ago:
  "Oh dear this is dead code. kdbg uses the fbcon, which always uses
  untiled, which means fbc will never be enabled. Also we have 0 users
  and 0 test coverage for kdbg on top of i915 (Jesse implemented it
  for fun years back). Imo just remove all this code."

Adding to what Daniel said: for kgdboc's KMS support,
intel_pipe_set_base_atomic() already manually disables FBC, so we
won't do the in_dbg_master() check there. This is essentially a revert

commit c924b934d0cd14a4559611da91f28f59acebe32a
Author: Jason Wessel <jason.wessel at windriver.com>
Date:   Thu Aug 5 09:22:32 2010 -0500
    i915: when kgdb is active display compression should be off

Besides, it is not clear what is the exact problem caused by FBC, and
why other features such as PSR, DRRS, IPS and RPM are not also
checking for in_dbg_master(). IMHO we should either remove the code as
suggested by Daniel or we add some nice comments explaining why is FBC
so special.

Cc: Jason Wessel <jason.wessel at windriver.com>
Cc: Jesse Barnes <jbarnes at virtuousgeek.org>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
 drivers/gpu/drm/i915/intel_fbc.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
index cbdf2f3..ba31359 100644
--- a/drivers/gpu/drm/i915/intel_fbc.c
+++ b/drivers/gpu/drm/i915/intel_fbc.c
@@ -857,12 +857,6 @@ static void __intel_fbc_update(struct intel_crtc *crtc)
 		goto out_disable;
-	/* If the kernel debugger is active, always disable compression */
-	if (in_dbg_master()) {
-		set_no_fbc_reason(dev_priv, "Kernel debugger is active");
-		goto out_disable;
-	}
 	/* It is possible for the required CFB size change without a
 	 * crtc->disable + crtc->enable since it is possible to change the
 	 * stride without triggering a full modeset. Since we try to

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