Attachment 45723 Details for Bug 36314 – Defend against a NULL crtc

[patch] Defend against a NULL crtc

0001-drm-i915-dp-Be-paranoid-in-case-we-disable-a-DP-befo.patch (text/plain), 2.57 KB, created by Chris Wilson on 2011-04-16 22:45:50 UTC

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Creator: Chris Wilson

Created: 2011-04-16 22:45:50 UTC

Size: 2.57 KB

patch

obsolete

>From 9a61b94f9565e481283736336aa4b886384b195f Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Sun, 17 Apr 2011 06:38:35 +0100
>Subject: [PATCH] drm/i915/dp: Be paranoid in case we disable a DP before it is attached
>
>Given that the hardware may be left in a random condition by the BIOS,
>it is conceivable that we then attempt to clear the DP_PIPEB_SELECT bit
>without us ever enabling/attaching the DP encoder to a pipe. Thus
>causing a NULL deference when we attempt to wait for a vblank on that
>crtc.
>
>Reported-by: Bryan Chris <bryan.christ@gmail.com>
>References: https://bugs.freedesktop.org/show_bug.cgi?id=36314
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>Cc: stable@kernel.org
>---
> drivers/gpu/drm/i915/intel_dp.c  |    3 +--
> drivers/gpu/drm/i915/intel_drv.h |    7 +++++++
> 2 files changed, 8 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>index 0daefca..819afca 100644
>--- a/drivers/gpu/drm/i915/intel_dp.c
>+++ b/drivers/gpu/drm/i915/intel_dp.c
>@@ -1470,7 +1470,6 @@ intel_dp_link_down(struct intel_dp *intel_dp)
> 
> 	if (!HAS_PCH_CPT(dev) &&
> 	    I915_READ(intel_dp->output_reg) & DP_PIPEB_SELECT) {
>-		struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.base.crtc);
> 		/* Hardware workaround: leaving our transcoder select
> 		 * set to transcoder B while it's off will prevent the
> 		 * corresponding HDMI output on transcoder A.
>@@ -1485,7 +1484,7 @@ intel_dp_link_down(struct intel_dp *intel_dp)
> 		/* Changes to enable or select take place the vblank
> 		 * after being written.
> 		 */
>-		intel_wait_for_vblank(dev, intel_crtc->pipe);
>+		intel_wait_for_crtc_vblank_safe(intel_dp->base.base.crtc);
> 	}
> 
> 	I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);
>diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>index f5b0d83..aeb1b98 100644
>--- a/drivers/gpu/drm/i915/intel_drv.h
>+++ b/drivers/gpu/drm/i915/intel_drv.h
>@@ -290,6 +290,13 @@ extern struct drm_display_mode *intel_crtc_mode_get(struct drm_device *dev,
> int intel_get_pipe_from_crtc_id(struct drm_device *dev, void *data,
> 				struct drm_file *file_priv);
> extern void intel_wait_for_vblank(struct drm_device *dev, int pipe);
>+static inline void intel_wait_for_crtc_vblank_safe(struct drm_crtc *crtc)
>+{
>+	if (crtc)
>+		intel_wait_for_vblank(crtc->dev, to_intel_crtc(crtc)->pipe);
>+	else
>+		msleep(50);
>+}
> extern void intel_wait_for_pipe_off(struct drm_device *dev, int pipe);
> extern struct drm_crtc *intel_get_load_detect_pipe(struct intel_encoder *intel_encoder,
> 						   struct drm_connector *connector,
>-- 
>1.7.4.1
>

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