From adf00b26d18e1b3570451296e03bcb20e4798cdd Mon Sep 17 00:00:00 2001 From: Paulo Zanoni Date: Tue, 25 Sep 2012 13:23:34 -0300 Subject: [PATCH] drm/i915: make sure we write all the DIP data bytes ... even if the actual infoframe is smaller than the maximum possible size. If we don't write all the 32 DIP data bytes the InfoFrame ECC may not be correctly calculated in some cases (e.g., when changing the port), and this will lead to black screens on HDMI monitors. The ECC value is generated by the hardware. I don't see how this should break anything since we're writing 0 and that should be the correct value, so this patch should be safe. Notice that on IVB and older we actually have 64 bytes available for VIDEO_DIP_DATA, but only bytes 0-31 actually store infoframe data: the others are either read-only ECC values or marked as "reserved". On HSW we only have 32 bytes, and the ECC value is stored on its own separate read-only register. See BSpec. This patch fixes bug #46761, which is marked as a regression introduced by commit 4e89ee174bb2da341bf90a84321c7008a3c9210d: drm/i915: set the DIP port on ibx_write_infoframe Before commit 4e89 we were just failing to send AVI infoframes when we needed to change the port, which can lead to black screens in some cases. After commit 4e89 we started sending infoframes, but with a possibly wrong ECC value. After this patch I hope we start sending correct infoframes. Version 2: - Improve commit message - Try to make the code more clear Cc: stable@vger.kernel.org Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=46761 Signed-off-by: Paulo Zanoni Reviewed-by: Rodrigo Vivi Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_reg.h | 4 ++++ drivers/gpu/drm/i915/intel_hdmi.c | 15 +++++++++++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index a828e90602b9..7637824c6a7d 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -1794,6 +1794,10 @@ /* Video Data Island Packet control */ #define VIDEO_DIP_DATA 0x61178 +/* Read the description of VIDEO_DIP_DATA (before Haswel) or VIDEO_DIP_ECC + * (Haswell and newer) to see which VIDEO_DIP_DATA byte corresponds to each byte + * of the infoframe structure specified by CEA-861. */ +#define VIDEO_DIP_DATA_SIZE 32 #define VIDEO_DIP_CTL 0x61170 /* Pre HSW: */ #define VIDEO_DIP_ENABLE (1 << 31) diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c index f9fb47cd1779..08f2b63d740a 100644 --- a/drivers/gpu/drm/i915/intel_hdmi.c +++ b/drivers/gpu/drm/i915/intel_hdmi.c @@ -151,6 +151,9 @@ static void g4x_write_infoframe(struct drm_encoder *encoder, I915_WRITE(VIDEO_DIP_DATA, *data); data++; } + /* Write every possible data byte to force correct ECC calculation. */ + for (; i < VIDEO_DIP_DATA_SIZE; i += 4) + I915_WRITE(VIDEO_DIP_DATA, 0); mmiowb(); val |= g4x_infoframe_enable(frame); @@ -186,6 +189,9 @@ static void ibx_write_infoframe(struct drm_encoder *encoder, I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), *data); data++; } + /* Write every possible data byte to force correct ECC calculation. */ + for (; i < VIDEO_DIP_DATA_SIZE; i += 4) + I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), 0); mmiowb(); val |= g4x_infoframe_enable(frame); @@ -224,6 +230,9 @@ static void cpt_write_infoframe(struct drm_encoder *encoder, I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), *data); data++; } + /* Write every possible data byte to force correct ECC calculation. */ + for (; i < VIDEO_DIP_DATA_SIZE; i += 4) + I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), 0); mmiowb(); val |= g4x_infoframe_enable(frame); @@ -259,6 +268,9 @@ static void vlv_write_infoframe(struct drm_encoder *encoder, I915_WRITE(VLV_TVIDEO_DIP_DATA(intel_crtc->pipe), *data); data++; } + /* Write every possible data byte to force correct ECC calculation. */ + for (; i < VIDEO_DIP_DATA_SIZE; i += 4) + I915_WRITE(VLV_TVIDEO_DIP_DATA(intel_crtc->pipe), 0); mmiowb(); val |= g4x_infoframe_enable(frame); @@ -292,6 +304,9 @@ static void hsw_write_infoframe(struct drm_encoder *encoder, I915_WRITE(data_reg + i, *data); data++; } + /* Write every possible data byte to force correct ECC calculation. */ + for (; i < VIDEO_DIP_DATA_SIZE; i += 4) + I915_WRITE(data_reg + i, 0); mmiowb(); val |= hsw_infoframe_enable(frame); -- 2.20.1