linux-kernel - [PATCH 4.2.y-ckt 14/53] drm/i915: Bail out of pipe config compute loop on LPT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 24 May 2016 10:54:44 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Chris Wilson <chris@...is-wilson.co.uk>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Daniel Vetter <daniel.vetter@...el.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jani Nikula <jani.nikula@...el.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 14/53] drm/i915: Bail out of pipe config compute loop on LPT

4.2.8-ckt11 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Daniel Vetter <daniel.vetter@...ll.ch>

commit 2700818ac9f935d8590715eecd7e8cadbca552b6 upstream.

LPT is pch, so might run into the fdi bandwidth constraint (especially
since it has only 2 lanes). But right now we just force pipe_bpp back
to 24, resulting in a nice loop (which we bail out with a loud
WARN_ON). Fix this.

Cc: Chris Wilson <chris@...is-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=93477
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
Tested-by: Chris Wilson <chris@...is-wilson.co.uk>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...ll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462264381-7573-1-git-send-email-daniel.vetter@ffwll.ch
(cherry picked from commit f58a1acc7e4a1f37d26124ce4c875c647fbcc61f)
Signed-off-by: Jani Nikula <jani.nikula@...el.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/gpu/drm/i915/intel_crt.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 521af2c..1b34f00 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -320,8 +320,14 @@ static bool intel_crt_compute_config(struct intel_encoder *encoder,
 		pipe_config->has_pch_encoder = true;
 
 	/* LPT FDI RX only supports 8bpc. */
-	if (HAS_PCH_LPT(dev))
+	if (HAS_PCH_LPT(dev)) {
+		if (pipe_config->bw_constrained && pipe_config->pipe_bpp < 24) {
+			DRM_DEBUG_KMS("LPT only supports 24bpp\n");
+			return false;
+		}
+
 		pipe_config->pipe_bpp = 24;
+	}
 
 	/* FDI must always be 2.7 GHz */
 	if (HAS_DDI(dev)) {
-- 
2.7.4