drm/nouveau/disp: add support for setting scdc parameters for high modes

When SCDC is supported, make sure that we configure the GPU and monitor
to the same parameters.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 39 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 1dbd1dcdcf15..5f163a025e89 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -36,6 +36,7 @@
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_plane_helper.h>
+#include <drm/drm_scdc_helper.h>
 #include <drm/drm_edid.h>
 
 #include <nvif/class.h>
@@ -531,6 +532,7 @@ nv50_hdmi_disable(struct drm_encoder *encoder, struct nouveau_crtc *nv_crtc)
 static void
 nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
 {
+        struct nouveau_drm *drm = nouveau_drm(encoder->dev);
         struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
         struct nouveau_crtc *nv_crtc = nouveau_crtc(encoder->crtc);
         struct nv50_disp *disp = nv50_disp(encoder->dev);
@@ -548,9 +550,12 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
                 .pwr.rekey = 56, /* binary driver, and tegra, constant */
         };
         struct nouveau_connector *nv_connector;
+        struct drm_hdmi_info *hdmi;
         u32 max_ac_packet;
         union hdmi_infoframe avi_frame;
         union hdmi_infoframe vendor_frame;
+        bool scdc_supported, high_tmds_clock_ratio = false, scrambling = false;
+        u8 config;
         int ret;
         int size;
 
@@ -558,8 +563,11 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
         if (!drm_detect_hdmi_monitor(nv_connector->edid))
                 return;
 
+        hdmi = &nv_connector->base.display_info.hdmi;
+        scdc_supported = hdmi->scdc.supported;
+
         ret = drm_hdmi_avi_infoframe_from_display_mode(&avi_frame.avi, mode,
-                                                       false);
+                                                       scdc_supported);
         if (!ret) {
                 /* We have an AVI InfoFrame, populate it to the display */
                 args.pwr.avi_infoframe_length
@@ -582,12 +590,42 @@ nv50_hdmi_enable(struct drm_encoder *encoder, struct drm_display_mode *mode)
         max_ac_packet -= 18; /* constant from tegra */
         args.pwr.max_ac_packet = max_ac_packet / 32;
 
+        if (hdmi->scdc.scrambling.supported) {
+                high_tmds_clock_ratio = mode->clock > 340000;
+                scrambling = high_tmds_clock_ratio ||
+                        hdmi->scdc.scrambling.low_rates;
+        }
+
+        args.pwr.scdc =
+                NV50_DISP_SOR_HDMI_PWR_V0_SCDC_SCRAMBLE * scrambling |
+                NV50_DISP_SOR_HDMI_PWR_V0_SCDC_DIV_BY_4 * high_tmds_clock_ratio;
+
         size = sizeof(args.base)
                 + sizeof(args.pwr)
                 + args.pwr.avi_infoframe_length
                 + args.pwr.vendor_infoframe_length;
         nvif_mthd(&disp->disp->object, 0, &args, size);
+
         nv50_audio_enable(encoder, mode);
+
+        /* If SCDC is supported by the downstream monitor, update
+         * divider / scrambling settings to what we programmed above.
+         */
+        if (!hdmi->scdc.scrambling.supported)
+                return;
+
+        ret = drm_scdc_readb(nv_encoder->i2c, SCDC_TMDS_CONFIG, &config);
+        if (ret < 0) {
+                NV_ERROR(drm, "Failure to read SCDC_TMDS_CONFIG: %d\n", ret);
+                return;
+        }
+        config &= ~(SCDC_TMDS_BIT_CLOCK_RATIO_BY_40 | SCDC_SCRAMBLING_ENABLE);
+        config |= SCDC_TMDS_BIT_CLOCK_RATIO_BY_40 * high_tmds_clock_ratio;
+        config |= SCDC_SCRAMBLING_ENABLE * scrambling;
+        ret = drm_scdc_writeb(nv_encoder->i2c, SCDC_TMDS_CONFIG, config);
+        if (ret < 0)
+                NV_ERROR(drm, "Failure to write SCDC_TMDS_CONFIG = 0x%02x: %d\n",
+                         config, ret);
 }
 
 /******************************************************************************