drm/nouveau/disp/dp: generate supported link rates table at detect time

Replaces the static list used during link training with a table built
dynamically from the union of source and sink capabilities.

Preparation for adding support for HBR3, LTTPR and eDP 1.4 link rates.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Karol Herbst <kherbst@redhat.com>
Link: https://gitlab.freedesktop.org/drm/nouveau/-/merge_requests/17

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
index 3c0554a..8b49398 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
@@ -350,63 +350,13 @@ nvkm_dp_train_init(struct nvkm_dp *dp)
        }
 }
 
-static const struct dp_rates {
-       u32 rate;
-       u8  bw;
-       u8  nr;
-} nvkm_dp_rates[] = {
-       { 2160000, 0x14, 4 },
-       { 1080000, 0x0a, 4 },
-       { 1080000, 0x14, 2 },
-       {  648000, 0x06, 4 },
-       {  540000, 0x0a, 2 },
-       {  540000, 0x14, 1 },
-       {  324000, 0x06, 2 },
-       {  270000, 0x0a, 1 },
-       {  162000, 0x06, 1 },
-       {}
-};
-
 static int
 nvkm_dp_train(struct nvkm_dp *dp, u32 dataKBps)
 {
        struct nvkm_ior *ior = dp->outp.ior;
-       const u8 sink_nr = dp->dpcd[DPCD_RC02] & DPCD_RC02_MAX_LANE_COUNT;
-       const u8 sink_bw = dp->dpcd[DPCD_RC01_MAX_LINK_RATE];
-       const u8 outp_nr = dp->outp.info.dpconf.link_nr;
-       const u8 outp_bw = dp->outp.info.dpconf.link_bw;
-       const struct dp_rates *failsafe = NULL, *cfg;
-       int ret = -EINVAL;
+       int ret = -EINVAL, nr, rate;
        u8  pwr;
 
-       /* Find the lowest configuration of the OR that can support
-        * the required link rate.
-        *
-        * We will refuse to program the OR to lower rates, even if
-        * link training fails at higher rates (or even if the sink
-        * can't support the rate at all, though the DD is supposed
-        * to prevent such situations from happening).
-        *
-        * Attempting to do so can cause the entire display to hang,
-        * and it's better to have a failed modeset than that.
-        */
-       for (cfg = nvkm_dp_rates; cfg->rate; cfg++) {
-               if (cfg->nr <= outp_nr && cfg->bw <= outp_bw) {
-                       /* Try to respect sink limits too when selecting
-                        * lowest link configuration.
-                        */
-                       if (!failsafe ||
-                           (cfg->nr <= sink_nr && cfg->bw <= sink_bw))
-                               failsafe = cfg;
-               }
-
-               if (failsafe && cfg[1].rate < dataKBps)
-                       break;
-       }
-
-       if (WARN_ON(!failsafe))
-               return ret;
-
        /* Ensure sink is not in a low-power state. */
        if (!nvkm_rdaux(dp->aux, DPCD_SC00, &pwr, 1)) {
                if ((pwr & DPCD_SC00_SET_POWER) != DPCD_SC00_SET_POWER_D0) {
@@ -416,25 +366,22 @@ nvkm_dp_train(struct nvkm_dp *dp, u32 dataKBps)
                }
        }
 
+       ior->dp.mst = dp->lt.mst;
+       ior->dp.ef = dp->dpcd[DPCD_RC02] & DPCD_RC02_ENHANCED_FRAME_CAP;
+       ior->dp.nr = 0;
+
        /* Link training. */
-       OUTP_DBG(&dp->outp, "training (min: %d x %d MB/s)",
-                failsafe->nr, failsafe->bw * 27);
+       OUTP_DBG(&dp->outp, "training");
        nvkm_dp_train_init(dp);
-       for (cfg = nvkm_dp_rates; ret < 0 && cfg <= failsafe; cfg++) {
-               /* Skip configurations not supported by both OR and sink. */
-               if ((cfg->nr > outp_nr || cfg->bw > outp_bw ||
-                    cfg->nr > sink_nr || cfg->bw > sink_bw)) {
-                       if (cfg != failsafe)
-                               continue;
-                       OUTP_ERR(&dp->outp, "link rate unsupported by sink");
+       for (nr = dp->links; ret < 0 && nr; nr >>= 1) {
+               for (rate = 0; ret < 0 && rate < dp->rates; rate++) {
+                       if (dp->rate[rate].rate * nr >= dataKBps || WARN_ON(!ior->dp.nr)) {
+                               /* Program selected link configuration. */
+                               ior->dp.bw = dp->rate[rate].rate / 27000;
+                               ior->dp.nr = nr;
+                               ret = nvkm_dp_train_links(dp);
+                       }
                }
-               ior->dp.mst = dp->lt.mst;
-               ior->dp.ef = dp->dpcd[DPCD_RC02] & DPCD_RC02_ENHANCED_FRAME_CAP;
-               ior->dp.bw = cfg->bw;
-               ior->dp.nr = cfg->nr;
-
-               /* Program selected link configuration. */
-               ret = nvkm_dp_train_links(dp);
        }
        nvkm_dp_train_fini(dp);
        if (ret < 0)
@@ -543,9 +490,32 @@ nvkm_dp_enable(struct nvkm_dp *dp, bool enable)
                        dp->present = true;
                }
 
-               if (!nvkm_rdaux(aux, DPCD_RC00_DPCD_REV, dp->dpcd,
-                               sizeof(dp->dpcd)))
+               if (!nvkm_rdaux(aux, DPCD_RC00_DPCD_REV, dp->dpcd, sizeof(dp->dpcd))) {
+                       const u8 rates[] = { 0x14, 0x0a, 0x06, 0 };
+                       const u8 *rate;
+                       int rate_max;
+
+                       dp->rates = 0;
+                       dp->links = dp->dpcd[DPCD_RC02] & DPCD_RC02_MAX_LANE_COUNT;
+                       dp->links = min(dp->links, dp->outp.info.dpconf.link_nr);
+
+                       rate_max = dp->dpcd[DPCD_RC01_MAX_LINK_RATE];
+                       rate_max = min(rate_max, dp->outp.info.dpconf.link_bw);
+
+                       if (1) {
+                               for (rate = rates; *rate; rate++) {
+                                       if (*rate <= rate_max) {
+                                               if (WARN_ON(dp->rates == ARRAY_SIZE(dp->rate)))
+                                                       break;
+
+                                               dp->rate[dp->rates].rate = *rate * 27000;
+                                               dp->rates++;
+                                       }
+                               }
+                       }
+
                        return true;
+               }
        }
 
        if (dp->present) {

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.h b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.h
index 9ce91f7..8a8d0da 100644 (file)
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.h
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.h
@@ -20,6 +20,12 @@ struct nvkm_dp {
        bool present;
        u8 dpcd[16];
 
+       struct {
+               u32 rate;
+       } rate[3];
+       int rates;
+       int links;
+
        struct mutex mutex;
        struct {
                atomic_t done;