drm/nv30: Workaround dual TMDS brain damage.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 35 insertions, 4 deletions

diff --git a/drivers/gpu/drm/nouveau/nv04_dfp.c b/drivers/gpu/drm/nouveau/nv04_dfp.c
index 9871570d2ff4..a5dcf7685800 100644
--- a/drivers/gpu/drm/nouveau/nv04_dfp.c
+++ b/drivers/gpu/drm/nouveau/nv04_dfp.c
@@ -146,6 +146,36 @@ void nv04_dfp_update_fp_control(struct drm_encoder *encoder, int mode)
         }
 }
 
+static struct drm_encoder *get_tmds_slave(struct drm_encoder *encoder)
+{
+        struct drm_device *dev = encoder->dev;
+        struct dcb_entry *dcb = nouveau_encoder(encoder)->dcb;
+        struct drm_encoder *slave;
+
+        if (dcb->type != OUTPUT_TMDS || dcb->location == DCB_LOC_ON_CHIP)
+                return NULL;
+
+        /* Some BIOSes (e.g. the one in a Quadro FX1000) report several
+         * TMDS transmitters at the same I2C address, in the same I2C
+         * bus. This can still work because in that case one of them is
+         * always hard-wired to a reasonable configuration using straps,
+         * and the other one needs to be programmed.
+         *
+         * I don't think there's a way to know which is which, even the
+         * blob programs the one exposed via I2C for *both* heads, so
+         * let's do the same.
+         */
+        list_for_each_entry(slave, &dev->mode_config.encoder_list, head) {
+                struct dcb_entry *slave_dcb = nouveau_encoder(slave)->dcb;
+
+                if (slave_dcb->type == OUTPUT_TMDS && get_slave_funcs(slave) &&
+                    slave_dcb->tmdsconf.slave_addr == dcb->tmdsconf.slave_addr)
+                        return slave;
+        }
+
+        return NULL;
+}
+
 static bool nv04_dfp_mode_fixup(struct drm_encoder *encoder,
                                 struct drm_display_mode *mode,
                                 struct drm_display_mode *adjusted_mode)
@@ -432,9 +462,9 @@ static void nv04_dfp_commit(struct drm_encoder *encoder)
                 NVWriteRAMDAC(dev, 0, NV_PRAMDAC_TEST_CONTROL + nv04_dac_output_offset(encoder), 0x00100000);
 
         /* Init external transmitters */
-        if (get_slave_funcs(encoder))
-                get_slave_funcs(encoder)->mode_set(encoder, &nv_encoder->mode,
-                                                   &nv_encoder->mode);
+        if (get_tmds_slave(encoder))
+                get_slave_funcs(get_tmds_slave(encoder))->mode_set(
+                        encoder, &nv_encoder->mode, &nv_encoder->mode);
 
         helper->dpms(encoder, DRM_MODE_DPMS_ON);
 
@@ -581,7 +611,8 @@ static void nv04_tmds_slave_init(struct drm_encoder *encoder)
         };
         int type;
 
-        if (!nv_gf4_disp_arch(dev) || !i2c)
+        if (!nv_gf4_disp_arch(dev) || !i2c ||
+            get_tmds_slave(encoder))
                 return;
 
         type = nouveau_i2c_identify(dev, "TMDS transmitter", info, 2);