drm/i915: Add support for VGA load detection (pre-945).

Two approaches for VGA detections: hot plug detection for 945G onwards
and load pipe detection for Pre-945G.  Load pipe detection will get one free
pipe, set border color as red and blue, then check CRT status by
swf register.  This is a sync-up with the 2D driver.

Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 147 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 19148c3df637..640f5158effc 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -198,9 +198,142 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector)
         return intel_ddc_probe(intel_output);
 }
 
+static enum drm_connector_status
+intel_crt_load_detect(struct drm_crtc *crtc, struct intel_output *intel_output)
+{
+        struct drm_encoder *encoder = &intel_output->enc;
+        struct drm_device *dev = encoder->dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+        uint32_t pipe = intel_crtc->pipe;
+        uint32_t save_bclrpat;
+        uint32_t save_vtotal;
+        uint32_t vtotal, vactive;
+        uint32_t vsample;
+        uint32_t vblank, vblank_start, vblank_end;
+        uint32_t dsl;
+        uint32_t bclrpat_reg;
+        uint32_t vtotal_reg;
+        uint32_t vblank_reg;
+        uint32_t vsync_reg;
+        uint32_t pipeconf_reg;
+        uint32_t pipe_dsl_reg;
+        uint8_t st00;
+        enum drm_connector_status status;
+
+        if (pipe == 0) {
+                bclrpat_reg = BCLRPAT_A;
+                vtotal_reg = VTOTAL_A;
+                vblank_reg = VBLANK_A;
+                vsync_reg = VSYNC_A;
+                pipeconf_reg = PIPEACONF;
+                pipe_dsl_reg = PIPEADSL;
+        } else {
+                bclrpat_reg = BCLRPAT_B;
+                vtotal_reg = VTOTAL_B;
+                vblank_reg = VBLANK_B;
+                vsync_reg = VSYNC_B;
+                pipeconf_reg = PIPEBCONF;
+                pipe_dsl_reg = PIPEBDSL;
+        }
+
+        save_bclrpat = I915_READ(bclrpat_reg);
+        save_vtotal = I915_READ(vtotal_reg);
+        vblank = I915_READ(vblank_reg);
+
+        vtotal = ((save_vtotal >> 16) & 0xfff) + 1;
+        vactive = (save_vtotal & 0x7ff) + 1;
+
+        vblank_start = (vblank & 0xfff) + 1;
+        vblank_end = ((vblank >> 16) & 0xfff) + 1;
+
+        /* Set the border color to purple. */
+        I915_WRITE(bclrpat_reg, 0x500050);
+
+        if (IS_I9XX(dev)) {
+                uint32_t pipeconf = I915_READ(pipeconf_reg);
+                I915_WRITE(pipeconf_reg, pipeconf | PIPECONF_FORCE_BORDER);
+                /* Wait for next Vblank to substitue
+                 * border color for Color info */
+                intel_wait_for_vblank(dev);
+                st00 = I915_READ8(VGA_MSR_WRITE);
+                status = ((st00 & (1 << 4)) != 0) ?
+                        connector_status_connected :
+                        connector_status_disconnected;
+
+                I915_WRITE(pipeconf_reg, pipeconf);
+        } else {
+                bool restore_vblank = false;
+                int count, detect;
+
+                /*
+                * If there isn't any border, add some.
+                * Yes, this will flicker
+                */
+                if (vblank_start <= vactive && vblank_end >= vtotal) {
+                        uint32_t vsync = I915_READ(vsync_reg);
+                        uint32_t vsync_start = (vsync & 0xffff) + 1;
+
+                        vblank_start = vsync_start;
+                        I915_WRITE(vblank_reg,
+                                   (vblank_start - 1) |
+                                   ((vblank_end - 1) << 16));
+                        restore_vblank = true;
+                }
+                /* sample in the vertical border, selecting the larger one */
+                if (vblank_start - vactive >= vtotal - vblank_end)
+                        vsample = (vblank_start + vactive) >> 1;
+                else
+                        vsample = (vtotal + vblank_end) >> 1;
+
+                /*
+                 * Wait for the border to be displayed
+                 */
+                while (I915_READ(pipe_dsl_reg) >= vactive)
+                        ;
+                while ((dsl = I915_READ(pipe_dsl_reg)) <= vsample)
+                        ;
+                /*
+                 * Watch ST00 for an entire scanline
+                 */
+                detect = 0;
+                count = 0;
+                do {
+                        count++;
+                        /* Read the ST00 VGA status register */
+                        st00 = I915_READ8(VGA_MSR_WRITE);
+                        if (st00 & (1 << 4))
+                                detect++;
+                } while ((I915_READ(pipe_dsl_reg) == dsl));
+
+                /* restore vblank if necessary */
+                if (restore_vblank)
+                        I915_WRITE(vblank_reg, vblank);
+                /*
+                 * If more than 3/4 of the scanline detected a monitor,
+                 * then it is assumed to be present. This works even on i830,
+                 * where there isn't any way to force the border color across
+                 * the screen
+                 */
+                status = detect * 4 > count * 3 ?
+                         connector_status_connected :
+                         connector_status_disconnected;
+        }
+
+        /* Restore previous settings */
+        I915_WRITE(bclrpat_reg, save_bclrpat);
+
+        return status;
+}
+
 static enum drm_connector_status intel_crt_detect(struct drm_connector *connector)
 {
         struct drm_device *dev = connector->dev;
+        struct intel_output *intel_output = to_intel_output(connector);
+        struct drm_encoder *encoder = &intel_output->enc;
+        struct drm_crtc *crtc;
+        int dpms_mode;
+        enum drm_connector_status status;
 
         if (IS_I9XX(dev) && !IS_I915G(dev) && !IS_I915GM(dev)) {
                 if (intel_crt_detect_hotplug(connector))
@@ -212,8 +345,20 @@ static enum drm_connector_status intel_crt_detect(struct drm_connector *connecto
         if (intel_crt_detect_ddc(connector))
                 return connector_status_connected;
 
-        /* TODO use load detect */
-        return connector_status_unknown;
+        /* for pre-945g platforms use load detect */
+        if (encoder->crtc && encoder->crtc->enabled) {
+                status = intel_crt_load_detect(encoder->crtc, intel_output);
+        } else {
+                crtc = intel_get_load_detect_pipe(intel_output,
+                                                  NULL, &dpms_mode);
+                if (crtc) {
+                        status = intel_crt_load_detect(crtc, intel_output);
+                        intel_release_load_detect_pipe(intel_output, dpms_mode);
+                } else
+                        status = connector_status_unknown;
+        }
+
+        return status;
 }
 
 static void intel_crt_destroy(struct drm_connector *connector)