Add a optional properties to change LVDS output voltage. This should not
be static as this depends mainly on the connected display voltage
requirement. We have three properties:
- "ti,lvds-termination-ohms", which sets near end termination,
- "ti,lvds-vod-swing-data-microvolt" and
- "ti,lvds-vod-swing-clock-microvolt" which both set LVDS differential
output voltage for data and clock lanes. They are defined as an array
with min and max values. The appropriate bitfiled will be set if
selected constraints can be met.
If "ti,lvds-termination-ohms" is not defined the default of 200 Ohm near
end termination will be used. Selecting only one:
"ti,lvds-vod-swing-data-microvolt" or
"ti,lvds-vod-swing-clock-microvolt" can be done, but the output voltage
constraint for only data/clock lanes will be met. Setting both is
recommended.
Signed-off-by: Andrej Picej <andrej.picej@xxxxxxxxx>
---
Changes in v3:
- use microvolts for default array values 1000 mV -> 1000000 uV.
Changes in v2:
- use datasheet tables to get the proper configuration
- since major change was done change the authorship to myself
---
drivers/gpu/drm/bridge/ti-sn65dsi83.c | 144 +++++++++++++++++++++++++-
1 file changed, 141 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 57a7ed13f996..1a070df5ea12 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -132,6 +132,16 @@
#define REG_IRQ_STAT_CHA_SOT_BIT_ERR BIT(2)
#define REG_IRQ_STAT_CHA_PLL_UNLOCK BIT(0)
+enum sn65dsi83_channel {
+ CHANNEL_A,
+ CHANNEL_B
+};
+
+enum sn65dsi83_lvds_term {
+ OHM_100,
+ OHM_200
+};
+
enum sn65dsi83_model {
MODEL_SN65DSI83,
MODEL_SN65DSI84,
@@ -147,6 +157,10 @@ struct sn65dsi83 {
struct regulator *vcc;
bool lvds_dual_link;
bool lvds_dual_link_even_odd_swap;
+ int lvdsA_vod_swing_conf;
+ int lvdsB_vod_swing_conf;
+ int lvdsA_term_conf;
+ int lvdsB_term_conf;
};
static const struct regmap_range sn65dsi83_readable_ranges[] = {
@@ -237,6 +251,36 @@ static const struct regmap_config sn65dsi83_regmap_config = {
.max_register = REG_IRQ_STAT,
};
+static const int lvds_vod_swing_data_table[2][4][2] = {
+ { /* 100 Ohm */
+ { 180000, 313000 },
+ { 215000, 372000 },
+ { 250000, 430000 },
+ { 290000, 488000 },
+ },
+ { /* 200 Ohm */
+ { 150000, 261000 },
+ { 200000, 346000 },
+ { 250000, 428000 },
+ { 300000, 511000 },
+ },
+};
+
+static const int lvds_vod_swing_clock_table[2][4][2] = {
+ { /* 100 Ohm */
+ { 140000, 244000 },
+ { 168000, 290000 },
+ { 195000, 335000 },
+ { 226000, 381000 },
+ },
+ { /* 200 Ohm */
+ { 117000, 204000 },
+ { 156000, 270000 },
+ { 195000, 334000 },
+ { 234000, 399000 },
+ },
+};
+
static struct sn65dsi83 *bridge_to_sn65dsi83(struct drm_bridge *bridge)
{
return container_of(bridge, struct sn65dsi83, bridge);
@@ -435,12 +479,16 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
val |= REG_LVDS_FMT_LVDS_LINK_CFG;
regmap_write(ctx->regmap, REG_LVDS_FMT, val);
- regmap_write(ctx->regmap, REG_LVDS_VCOM, 0x05);
+ regmap_write(ctx->regmap, REG_LVDS_VCOM,
+ REG_LVDS_VCOM_CHA_LVDS_VOD_SWING(ctx->lvdsA_vod_swing_conf) |
+ REG_LVDS_VCOM_CHB_LVDS_VOD_SWING(ctx->lvdsB_vod_swing_conf));
regmap_write(ctx->regmap, REG_LVDS_LANE,
(ctx->lvds_dual_link_even_odd_swap ?
REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
- REG_LVDS_LANE_CHA_LVDS_TERM |
- REG_LVDS_LANE_CHB_LVDS_TERM);
+ (ctx->lvdsA_term_conf ?
+ REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
+ (ctx->lvdsB_term_conf ?
+ REG_LVDS_LANE_CHB_LVDS_TERM : 0));
regmap_write(ctx->regmap, REG_LVDS_CM, 0x00);
le16val = cpu_to_le16(mode->hdisplay);
@@ -576,10 +624,96 @@ static const struct drm_bridge_funcs sn65dsi83_funcs = {
.atomic_get_input_bus_fmts = sn65dsi83_atomic_get_input_bus_fmts,
};
+static int sn65dsi83_select_lvds_vod_swing(struct device *dev,
+ u32 lvds_vod_swing_data[2], u32 lvds_vod_swing_clk[2], u8 lvds_term)
+{
+ int i;
+
+ for (i = 0; i <= 3; i++) {
+ if (lvds_vod_swing_data_table[lvds_term][i][0] >= lvds_vod_swing_data[0] &&
+ lvds_vod_swing_data_table[lvds_term][i][1] <= lvds_vod_swing_data[1] &&
+ lvds_vod_swing_clock_table[lvds_term][i][0] >= lvds_vod_swing_clk[0] &&
+ lvds_vod_swing_clock_table[lvds_term][i][1] <= lvds_vod_swing_clk[1])
+ return i;
+ }
+
+ dev_err(dev, "failed to find appropriate LVDS_VOD_SWING configuration\n");
+ return -EINVAL;
+}
+
+static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
+{
+ struct device *dev = ctx->dev;
+ struct device_node *endpoint;
+ /* Set so the property can be freely selected if not defined */
+ u32 lvds_vod_swing_data[2] = { 0, 1000000 };
+ u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
+ u32 lvds_term = 200;
+ u8 lvds_term_conf;
+ int endpoint_reg;
+ int lvds_vod_swing_conf;
+ int ret = 0;
+ int ret_data;
+ int ret_clock;
+
+ if (channel == CHANNEL_A)
+ endpoint_reg = 2;
+ else
+ endpoint_reg = 3;
+
+ endpoint = of_graph_get_endpoint_by_regs(dev->of_node, endpoint_reg, -1);
+ of_property_read_u32(endpoint, "ti,lvds-termination-ohms", &lvds_term);
+
+ if (lvds_term == 200)
+ lvds_term_conf = OHM_200;
+ else
+ lvds_term_conf = OHM_100;
+
+ if (channel == CHANNEL_A)
+ ctx->lvdsA_term_conf = lvds_term_conf;
+ else
+ ctx->lvdsB_term_conf = lvds_term_conf;
