diff options
| author | Douglas Anderson <dianders@chromium.org> | 2019-12-19 01:35:26 +0300 |
|---|---|---|
| committer | Neil Armstrong <narmstrong@baylibre.com> | 2020-02-13 12:21:10 +0300 |
| commit | 457622d9f99b9b2b44375d7e5e95cde5f66910f9 (patch) | |
| tree | fd6b3acdab705487898b5dc0bb44e34300e0ed6a | |
| parent | cf33de1799c65fd05fcf18b5983ac9b2640be1e8 (diff) | |
| download | linux-457622d9f99b9b2b44375d7e5e95cde5f66910f9.tar.xz | |
drm/bridge: ti-sn65dsi86: Read num lanes from the DP sink
At least one panel hooked up to the bridge (AUO B116XAK01) only
supports 1 lane of DP. Let's read this information and stop
hardcoding 4 DP lanes.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218143416.v3.5.Idbd0051d0de53f7e9d18a291ea33011c0854fcc6@changeid
| -rw-r--r-- | drivers/gpu/drm/bridge/ti-sn65dsi86.c | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c index 9cc0b2bb36ee..5c1c6ed387e0 100644 --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c @@ -313,8 +313,7 @@ static int ti_sn_bridge_attach(struct drm_bridge *bridge) goto err_dsi_host; } - /* TODO: setting to 4 lanes always for now */ - pdata->dp_lanes = 4; + /* TODO: setting to 4 MIPI lanes always for now */ dsi->lanes = 4; dsi->format = MIPI_DSI_FMT_RGB888; dsi->mode_flags = MIPI_DSI_MODE_VIDEO; @@ -511,12 +510,41 @@ static void ti_sn_bridge_set_video_timings(struct ti_sn_bridge *pdata) usleep_range(10000, 10500); /* 10ms delay recommended by spec */ } +static unsigned int ti_sn_get_max_lanes(struct ti_sn_bridge *pdata) +{ + u8 data; + int ret; + + ret = drm_dp_dpcd_readb(&pdata->aux, DP_MAX_LANE_COUNT, &data); + if (ret != 1) { + DRM_DEV_ERROR(pdata->dev, + "Can't read lane count (%d); assuming 4\n", ret); + return 4; + } + + return data & DP_LANE_COUNT_MASK; +} + static void ti_sn_bridge_enable(struct drm_bridge *bridge) { struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge); unsigned int val; int ret; + /* + * Run with the maximum number of lanes that the DP sink supports. + * + * Depending use cases, we might want to revisit this later because: + * - It's plausible that someone may have run fewer lines to the + * sink than the sink actually supports, assuming that the lines + * will just be driven at a higher rate. + * - The DP spec seems to indicate that it's more important to minimize + * the number of lanes than the link rate. + * + * If we do revisit, it would be important to measure the power impact. + */ + pdata->dp_lanes = ti_sn_get_max_lanes(pdata); + /* DSI_A lane config */ val = CHA_DSI_LANES(4 - pdata->dsi->lanes); regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG, |