From patchwork Mon Jan 7 20:38:05 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [3.5.y.z, extended, stable] Patch "drm/i915: drop buggy write to FDI_RX_CHICKEN register" has been added to staging queue Date: Mon, 07 Jan 2013 10:38:05 -0000 From: Herton Ronaldo Krzesinski X-Patchwork-Id: 210210 Message-Id: <1357591085-21840-1-git-send-email-herton.krzesinski@canonical.com> To: Daniel Vetter Cc: Jani Nikula , kernel-team@lists.ubuntu.com, Chris Wilson This is a note to let you know that I have just added a patch titled drm/i915: drop buggy write to FDI_RX_CHICKEN register to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Herton ------ >From f8110b87dd3e6b77a99d7ffc51831f225c212846 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Wed, 14 Nov 2012 17:47:39 +0100 Subject: [PATCH] drm/i915: drop buggy write to FDI_RX_CHICKEN register commit 607a6f7a6621f65706ff536b2615ee65b5c2f575 upstream. Jani Nikula noticed that the parentheses are wrong and we & the bit with the register address instead of the read-back value. He sent a patch to correct that. On second look, we write the same register in the previous line, and the w/a seems to be to set FDI_RX_PHASE_SYNC_POINTER_OVR to enable the logic, then keep always set FDI_RX_PHASE_SYNC_POINTER_OVR and toggle FDI_RX_PHASE_SYNC_POINTER_EN before/after enabling the pc transcoder. So the right things seems to be to simply kill the 2nd write. Cc: Jani Nikula Reviewed-by: Chris Wilson [danvet: Dropped a bogus ~ from the commit message that somehow crept in.] Signed-off-by: Daniel Vetter [ herton: this looks a good bug fix, which also makes the next patch, "drm/i915: disable cpt phase pointer fdi rx workaround", easier to apply ] Signed-off-by: Herton Ronaldo Krzesinski --- drivers/gpu/drm/i915/intel_display.c | 3 --- 1 file changed, 3 deletions(-) -- 1.7.9.5 diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index c69444a..98ea04e 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -2609,9 +2609,6 @@ static void ironlake_fdi_disable(struct drm_crtc *crtc) /* Ironlake workaround, disable clock pointer after downing FDI */ if (HAS_PCH_IBX(dev)) { I915_WRITE(FDI_RX_CHICKEN(pipe), FDI_RX_PHASE_SYNC_POINTER_OVR); - I915_WRITE(FDI_RX_CHICKEN(pipe), - I915_READ(FDI_RX_CHICKEN(pipe) & - ~FDI_RX_PHASE_SYNC_POINTER_EN)); } else if (HAS_PCH_CPT(dev)) { cpt_phase_pointer_disable(dev, pipe); }