i915: enable AVI infoframe for intel_hdmi.c [v4]

This patch enables the sending of AVI infoframes in
drivers/gpu/drm/i915/intel_hdmi.c.

My receiver currently loses sync when the HDMI output on my computer
(DG45FC motherboard) is switched from 800x600 (the BIOS resolution) to
1920x1080 as part of the boot. Fixable by switching inputs on the receiver
a couple of times.

With this patch, my receiver has not lost sync yet (> 40 tries).

Fourth version, now based on drm-intel-next from:
git://git.kernel.org/pub/scm/linux/kernel/git/ickle/drm-intel.git

Two questions still remain:

I'm assuming that the sdvo hardware also stores a header ECC byte in
the MSB of the first dword - is this correct?

Does the SDVOB and SDVOC handling in intel_hdmi_set_avi_infoframe()
look correct?

Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 59 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index 6c3b2ecd59d5..0d0273e7b029 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -58,6 +58,60 @@ static struct intel_hdmi *intel_attached_hdmi(struct drm_connector *connector)
                             struct intel_hdmi, base);
 }
 
+void intel_dip_infoframe_csum(struct dip_infoframe *avi_if)
+{
+        uint8_t *data = (uint8_t *)avi_if;
+        uint8_t sum = 0;
+        unsigned i;
+
+        avi_if->checksum = 0;
+        avi_if->ecc = 0;
+
+        for (i = 0; i < sizeof(*avi_if); i++)
+                sum += data[i];
+
+        avi_if->checksum = 0x100 - sum;
+}
+
+static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder)
+{
+        struct dip_infoframe avi_if = {
+                .type = DIP_TYPE_AVI,
+                .ver = DIP_VERSION_AVI,
+                .len = DIP_LEN_AVI,
+        };
+        uint32_t *data = (uint32_t *)&avi_if;
+        struct drm_device *dev = encoder->dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
+        u32 port;
+        unsigned i;
+
+        if (!intel_hdmi->has_hdmi_sink)
+                return;
+
+        /* XXX first guess at handling video port, is this corrent? */
+        if (intel_hdmi->sdvox_reg == SDVOB)
+                port = VIDEO_DIP_PORT_B;
+        else if (intel_hdmi->sdvox_reg == SDVOC)
+                port = VIDEO_DIP_PORT_C;
+        else
+                return;
+
+        I915_WRITE(VIDEO_DIP_CTL, VIDEO_DIP_ENABLE | port |
+                   VIDEO_DIP_SELECT_AVI | VIDEO_DIP_FREQ_VSYNC);
+
+        intel_dip_infoframe_csum(&avi_if);
+        for (i = 0; i < sizeof(avi_if); i += 4) {
+                I915_WRITE(VIDEO_DIP_DATA, *data);
+                data++;
+        }
+
+        I915_WRITE(VIDEO_DIP_CTL, VIDEO_DIP_ENABLE | port |
+                   VIDEO_DIP_SELECT_AVI | VIDEO_DIP_FREQ_VSYNC |
+                   VIDEO_DIP_ENABLE_AVI);
+}
+
 static void intel_hdmi_mode_set(struct drm_encoder *encoder,
                                 struct drm_display_mode *mode,
                                 struct drm_display_mode *adjusted_mode)
@@ -79,8 +133,10 @@ static void intel_hdmi_mode_set(struct drm_encoder *encoder,
         if (intel_hdmi->has_hdmi_sink && HAS_PCH_CPT(dev))
                 sdvox |= HDMI_MODE_SELECT;
 
-        if (intel_hdmi->has_audio)
+        if (intel_hdmi->has_audio) {
                 sdvox |= SDVO_AUDIO_ENABLE;
+                sdvox |= SDVO_NULL_PACKETS_DURING_VSYNC;
+        }
 
         if (intel_crtc->pipe == 1) {
                 if (HAS_PCH_CPT(dev))
@@ -91,6 +147,8 @@ static void intel_hdmi_mode_set(struct drm_encoder *encoder,
 
         I915_WRITE(intel_hdmi->sdvox_reg, sdvox);
         POSTING_READ(intel_hdmi->sdvox_reg);
+
+        intel_hdmi_set_avi_infoframe(encoder);
 }
 
 static void intel_hdmi_dpms(struct drm_encoder *encoder, int mode)