* [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support
@ 2026-07-09 12:58 Wojciech Dubowik
2026-07-09 13:29 ` Laurent Pinchart
0 siblings, 1 reply; 4+ messages in thread
From: Wojciech Dubowik @ 2026-07-09 12:58 UTC (permalink / raw)
To: linux-kernel
Cc: Wojciech Dubowik, Andrzej Hajda, Neil Armstrong, Robert Foss,
Laurent Pinchart, Jonas Karlman, Jernej Skrabec, Luca Ceresoli,
Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, dri-devel
From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
The chip supports output lvds lanes in two orders, default <1 2 3 4>
and <4 3 2 1>. Add parsing of an optional output lvds data-lanes
property so we can inform chip that the lanes have been reversed.
Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
Changes in v2:
- Parse existing data-lanes property instead of ading new DT
bindings
---
drivers/gpu/drm/bridge/ti-sn65dsi83.c | 50 +++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 42b451432bbb..4945d4c960c4 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -148,6 +148,18 @@ enum sn65dsi83_lvds_term {
OHM_200
};
+enum {
+ NORMAL_LANE_MAPPING,
+ REVERSE_LANE_MAPPING,
+};
+
+#define DATA_LANES_COUNT 4
+
+static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
+ [NORMAL_LANE_MAPPING] = { 1, 2, 3, 4 },
+ [REVERSE_LANE_MAPPING] = { 4, 3, 2, 1},
+};
+
enum sn65dsi83_model {
MODEL_SN65DSI83,
MODEL_SN65DSI84,
@@ -163,6 +175,7 @@ struct sn65dsi83 {
struct regulator *vcc;
bool lvds_dual_link;
bool lvds_dual_link_even_odd_swap;
+ bool lvds_reverse_lanes_conf[2];
int lvds_vod_swing_conf[2];
int lvds_term_conf[2];
int irq;
@@ -644,6 +657,10 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
regmap_write(ctx->regmap, REG_LVDS_LANE,
(ctx->lvds_dual_link_even_odd_swap ?
REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
+ (ctx->lvds_reverse_lanes_conf[CHANNEL_A] ?
+ REG_LVDS_LANE_CHA_REVERSE_LVDS : 0) |
+ (ctx->lvds_reverse_lanes_conf[CHANNEL_B] ?
+ REG_LVDS_LANE_CHB_REVERSE_LVDS : 0) |
(ctx->lvds_term_conf[CHANNEL_A] ?
REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
(ctx->lvds_term_conf[CHANNEL_B] ?
@@ -832,10 +849,12 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
/* Set default near end terminataion to 200 Ohm */
u32 lvds_term = 200;
+ u32 data_lanes[DATA_LANES_COUNT];
int lvds_vod_swing_conf;
int ret = 0;
int ret_data;
int ret_clock;
+ int i, j;
if (channel == CHANNEL_A)
endpoint_reg = 2;
@@ -854,6 +873,37 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
goto exit;
}
+ ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
+ ARRAY_SIZE(data_lanes));
+ if (ret_data != 0 && ret_data != -EINVAL) {
+ ret = ret_data;
+ goto exit;
+ }
+
+ if (!ret_data) {
+ for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
+ for (j = 0; j < DATA_LANES_COUNT; j++) {
+ if (data_lanes[j] != supported_data_lane_mapping[i][j])
+ break;
+ }
+
+ if (j == DATA_LANES_COUNT)
+ break;
+ }
+
+ switch (i) {
+ case NORMAL_LANE_MAPPING:
+ break;
+ case REVERSE_LANE_MAPPING:
+ ctx->lvds_reverse_lanes_conf[channel] = true;
+ break;
+ default:
+ dev_err(dev, "invalid data lanes mapping\n");
+ ret = -EINVAL;
+ goto exit;
+ }
+ }
+
ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
if (ret_data != 0 && ret_data != -EINVAL) {
--
2.47.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support
2026-07-09 12:58 [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support Wojciech Dubowik
@ 2026-07-09 13:29 ` Laurent Pinchart
2026-07-10 8:01 ` Wojciech Dubowik
0 siblings, 1 reply; 4+ messages in thread
From: Laurent Pinchart @ 2026-07-09 13:29 UTC (permalink / raw)
To: Wojciech Dubowik
Cc: linux-kernel, Andrzej Hajda, Neil Armstrong, Robert Foss,
Jonas Karlman, Jernej Skrabec, Luca Ceresoli, Maarten Lankhorst,
Maxime Ripard, Thomas Zimmermann, David Airlie, Simona Vetter,
dri-devel
On Thu, Jul 09, 2026 at 02:58:09PM +0200, Wojciech Dubowik wrote:
> From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
>
> The chip supports output lvds lanes in two orders, default <1 2 3 4>
> and <4 3 2 1>. Add parsing of an optional output lvds data-lanes
> property so we can inform chip that the lanes have been reversed.
>
> Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> ---
> Changes in v2:
> - Parse existing data-lanes property instead of ading new DT
> bindings
You still need to update the bindings to relax the ordering requirement
of the data-lanes property.
Does the device support less than 4 data lanes ? If not, the bindings
will also need to be updated to reflect that.
> ---
> drivers/gpu/drm/bridge/ti-sn65dsi83.c | 50 +++++++++++++++++++++++++++
> 1 file changed, 50 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index 42b451432bbb..4945d4c960c4 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -148,6 +148,18 @@ enum sn65dsi83_lvds_term {
> OHM_200
> };
>
> +enum {
> + NORMAL_LANE_MAPPING,
> + REVERSE_LANE_MAPPING,
> +};
> +
> +#define DATA_LANES_COUNT 4
> +
> +static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
> + [NORMAL_LANE_MAPPING] = { 1, 2, 3, 4 },
> + [REVERSE_LANE_MAPPING] = { 4, 3, 2, 1},
> +};
> +
> enum sn65dsi83_model {
> MODEL_SN65DSI83,
> MODEL_SN65DSI84,
> @@ -163,6 +175,7 @@ struct sn65dsi83 {
> struct regulator *vcc;
> bool lvds_dual_link;
> bool lvds_dual_link_even_odd_swap;
> + bool lvds_reverse_lanes_conf[2];
> int lvds_vod_swing_conf[2];
> int lvds_term_conf[2];
> int irq;
> @@ -644,6 +657,10 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
> regmap_write(ctx->regmap, REG_LVDS_LANE,
> (ctx->lvds_dual_link_even_odd_swap ?
> REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
> + (ctx->lvds_reverse_lanes_conf[CHANNEL_A] ?
> + REG_LVDS_LANE_CHA_REVERSE_LVDS : 0) |
> + (ctx->lvds_reverse_lanes_conf[CHANNEL_B] ?
> + REG_LVDS_LANE_CHB_REVERSE_LVDS : 0) |
> (ctx->lvds_term_conf[CHANNEL_A] ?
> REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
> (ctx->lvds_term_conf[CHANNEL_B] ?
> @@ -832,10 +849,12 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
> u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
> /* Set default near end terminataion to 200 Ohm */
> u32 lvds_term = 200;
> + u32 data_lanes[DATA_LANES_COUNT];
> int lvds_vod_swing_conf;
> int ret = 0;
> int ret_data;
> int ret_clock;
> + int i, j;
>
> if (channel == CHANNEL_A)
> endpoint_reg = 2;
> @@ -854,6 +873,37 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
> goto exit;
> }
>
> + ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
> + ARRAY_SIZE(data_lanes));
> + if (ret_data != 0 && ret_data != -EINVAL) {
> + ret = ret_data;
> + goto exit;
> + }
> +
> + if (!ret_data) {
I wish we could drop this check, but as the data-lanes property is not
documented as mandatory, I suppose not all device trees use it :-(
Could you, while at it, make the property mandatory in the bindings, to
ensure it gets specified in all future device trees (and fix in-tree
offenders, if any) ?
> + for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
> + for (j = 0; j < DATA_LANES_COUNT; j++) {
> + if (data_lanes[j] != supported_data_lane_mapping[i][j])
> + break;
> + }
> +
> + if (j == DATA_LANES_COUNT)
> + break;
> + }
> +
> + switch (i) {
> + case NORMAL_LANE_MAPPING:
> + break;
> + case REVERSE_LANE_MAPPING:
> + ctx->lvds_reverse_lanes_conf[channel] = true;
> + break;
> + default:
> + dev_err(dev, "invalid data lanes mapping\n");
> + ret = -EINVAL;
> + goto exit;
> + }
> + }
> +
> ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
> lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
> if (ret_data != 0 && ret_data != -EINVAL) {
--
Regards,
Laurent Pinchart
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support
2026-07-09 13:29 ` Laurent Pinchart
@ 2026-07-10 8:01 ` Wojciech Dubowik
0 siblings, 0 replies; 4+ messages in thread
From: Wojciech Dubowik @ 2026-07-10 8:01 UTC (permalink / raw)
To: Laurent Pinchart
Cc: linux-kernel, Andrzej Hajda, Neil Armstrong, Robert Foss,
Jonas Karlman, Jernej Skrabec, Luca Ceresoli, Maarten Lankhorst,
Maxime Ripard, Thomas Zimmermann, David Airlie, Simona Vetter,
dri-devel
On Thu, Jul 09, 2026 at 04:29:44PM +0300, Laurent Pinchart wrote:
Hi Laurent,
> On Thu, Jul 09, 2026 at 02:58:09PM +0200, Wojciech Dubowik wrote:
> > From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> >
> > The chip supports output lvds lanes in two orders, default <1 2 3 4>
> > and <4 3 2 1>. Add parsing of an optional output lvds data-lanes
> > property so we can inform chip that the lanes have been reversed.
> >
> > Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
> > ---
> > Changes in v2:
> > - Parse existing data-lanes property instead of ading new DT
> > bindings
>
> You still need to update the bindings to relax the ordering requirement
> of the data-lanes property.
The data-lanes have been defined for input nodes only. I will add an optinal
binding for output nodes which are handled here.
>
> Does the device support less than 4 data lanes ? If not, the bindings
> will also need to be updated to reflect that.
There are 4 output lanes only,
Regards,
Wojtek
>
> > ---
> > drivers/gpu/drm/bridge/ti-sn65dsi83.c | 50 +++++++++++++++++++++++++++
> > 1 file changed, 50 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > index 42b451432bbb..4945d4c960c4 100644
> > --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> > @@ -148,6 +148,18 @@ enum sn65dsi83_lvds_term {
> > OHM_200
> > };
> >
> > +enum {
> > + NORMAL_LANE_MAPPING,
> > + REVERSE_LANE_MAPPING,
> > +};
> > +
> > +#define DATA_LANES_COUNT 4
> > +
> > +static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
> > + [NORMAL_LANE_MAPPING] = { 1, 2, 3, 4 },
> > + [REVERSE_LANE_MAPPING] = { 4, 3, 2, 1},
> > +};
> > +
> > enum sn65dsi83_model {
> > MODEL_SN65DSI83,
> > MODEL_SN65DSI84,
> > @@ -163,6 +175,7 @@ struct sn65dsi83 {
> > struct regulator *vcc;
> > bool lvds_dual_link;
> > bool lvds_dual_link_even_odd_swap;
> > + bool lvds_reverse_lanes_conf[2];
> > int lvds_vod_swing_conf[2];
> > int lvds_term_conf[2];
> > int irq;
> > @@ -644,6 +657,10 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
> > regmap_write(ctx->regmap, REG_LVDS_LANE,
> > (ctx->lvds_dual_link_even_odd_swap ?
> > REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
> > + (ctx->lvds_reverse_lanes_conf[CHANNEL_A] ?
> > + REG_LVDS_LANE_CHA_REVERSE_LVDS : 0) |
> > + (ctx->lvds_reverse_lanes_conf[CHANNEL_B] ?
> > + REG_LVDS_LANE_CHB_REVERSE_LVDS : 0) |
> > (ctx->lvds_term_conf[CHANNEL_A] ?
> > REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
> > (ctx->lvds_term_conf[CHANNEL_B] ?
> > @@ -832,10 +849,12 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
> > u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
> > /* Set default near end terminataion to 200 Ohm */
> > u32 lvds_term = 200;
> > + u32 data_lanes[DATA_LANES_COUNT];
> > int lvds_vod_swing_conf;
> > int ret = 0;
> > int ret_data;
> > int ret_clock;
> > + int i, j;
> >
> > if (channel == CHANNEL_A)
> > endpoint_reg = 2;
> > @@ -854,6 +873,37 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
> > goto exit;
> > }
> >
> > + ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
> > + ARRAY_SIZE(data_lanes));
> > + if (ret_data != 0 && ret_data != -EINVAL) {
> > + ret = ret_data;
> > + goto exit;
> > + }
> > +
> > + if (!ret_data) {
>
> I wish we could drop this check, but as the data-lanes property is not
> documented as mandatory, I suppose not all device trees use it :-(
>
> Could you, while at it, make the property mandatory in the bindings, to
> ensure it gets specified in all future device trees (and fix in-tree
> offenders, if any) ?
>
> > + for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
> > + for (j = 0; j < DATA_LANES_COUNT; j++) {
> > + if (data_lanes[j] != supported_data_lane_mapping[i][j])
> > + break;
> > + }
> > +
> > + if (j == DATA_LANES_COUNT)
> > + break;
> > + }
> > +
> > + switch (i) {
> > + case NORMAL_LANE_MAPPING:
> > + break;
> > + case REVERSE_LANE_MAPPING:
> > + ctx->lvds_reverse_lanes_conf[channel] = true;
> > + break;
> > + default:
> > + dev_err(dev, "invalid data lanes mapping\n");
> > + ret = -EINVAL;
> > + goto exit;
> > + }
> > + }
> > +
> > ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
> > lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
> > if (ret_data != 0 && ret_data != -EINVAL) {
>
> --
> Regards,
>
> Laurent Pinchart
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support
@ 2026-07-10 8:26 Wojciech Dubowik
0 siblings, 0 replies; 4+ messages in thread
From: Wojciech Dubowik @ 2026-07-10 8:26 UTC (permalink / raw)
To: linux-kernel
Cc: Wojciech Dubowik, Andrzej Hajda, Neil Armstrong, Robert Foss,
Laurent Pinchart, Jonas Karlman, Jernej Skrabec, Luca Ceresoli,
Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie,
Simona Vetter, dri-devel
From: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
The chip supports output lvds lanes in two orders, default <1 2 3 4>
and <4 3 2 1>. Add parsing of an optional output lvds data-lanes
property so we can inform chip that the lanes have been reversed.
Signed-off-by: Wojciech Dubowik <Wojciech.Dubowik@mt.com>
---
Changes in v2:
- Parse existing data-lanes property instead of ading new DT
bindings
---
drivers/gpu/drm/bridge/ti-sn65dsi83.c | 50 +++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 42b451432bbb..4945d4c960c4 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -148,6 +148,18 @@ enum sn65dsi83_lvds_term {
OHM_200
};
+enum {
+ NORMAL_LANE_MAPPING,
+ REVERSE_LANE_MAPPING,
+};
+
+#define DATA_LANES_COUNT 4
+
+static const int supported_data_lane_mapping[][DATA_LANES_COUNT] = {
+ [NORMAL_LANE_MAPPING] = { 1, 2, 3, 4 },
+ [REVERSE_LANE_MAPPING] = { 4, 3, 2, 1},
+};
+
enum sn65dsi83_model {
MODEL_SN65DSI83,
MODEL_SN65DSI84,
@@ -163,6 +175,7 @@ struct sn65dsi83 {
struct regulator *vcc;
bool lvds_dual_link;
bool lvds_dual_link_even_odd_swap;
+ bool lvds_reverse_lanes_conf[2];
int lvds_vod_swing_conf[2];
int lvds_term_conf[2];
int irq;
@@ -644,6 +657,10 @@ static void sn65dsi83_atomic_pre_enable(struct drm_bridge *bridge,
regmap_write(ctx->regmap, REG_LVDS_LANE,
(ctx->lvds_dual_link_even_odd_swap ?
REG_LVDS_LANE_EVEN_ODD_SWAP : 0) |
+ (ctx->lvds_reverse_lanes_conf[CHANNEL_A] ?
+ REG_LVDS_LANE_CHA_REVERSE_LVDS : 0) |
+ (ctx->lvds_reverse_lanes_conf[CHANNEL_B] ?
+ REG_LVDS_LANE_CHB_REVERSE_LVDS : 0) |
(ctx->lvds_term_conf[CHANNEL_A] ?
REG_LVDS_LANE_CHA_LVDS_TERM : 0) |
(ctx->lvds_term_conf[CHANNEL_B] ?
@@ -832,10 +849,12 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
u32 lvds_vod_swing_clk[2] = { 0, 1000000 };
/* Set default near end terminataion to 200 Ohm */
u32 lvds_term = 200;
+ u32 data_lanes[DATA_LANES_COUNT];
int lvds_vod_swing_conf;
int ret = 0;
int ret_data;
int ret_clock;
+ int i, j;
if (channel == CHANNEL_A)
endpoint_reg = 2;
@@ -854,6 +873,37 @@ static int sn65dsi83_parse_lvds_endpoint(struct sn65dsi83 *ctx, int channel)
goto exit;
}
+ ret_data = of_property_read_u32_array(endpoint, "data-lanes", data_lanes,
+ ARRAY_SIZE(data_lanes));
+ if (ret_data != 0 && ret_data != -EINVAL) {
+ ret = ret_data;
+ goto exit;
+ }
+
+ if (!ret_data) {
+ for (i = 0; i < ARRAY_SIZE(supported_data_lane_mapping); i++) {
+ for (j = 0; j < DATA_LANES_COUNT; j++) {
+ if (data_lanes[j] != supported_data_lane_mapping[i][j])
+ break;
+ }
+
+ if (j == DATA_LANES_COUNT)
+ break;
+ }
+
+ switch (i) {
+ case NORMAL_LANE_MAPPING:
+ break;
+ case REVERSE_LANE_MAPPING:
+ ctx->lvds_reverse_lanes_conf[channel] = true;
+ break;
+ default:
+ dev_err(dev, "invalid data lanes mapping\n");
+ ret = -EINVAL;
+ goto exit;
+ }
+ }
+
ret_data = of_property_read_u32_array(endpoint, "ti,lvds-vod-swing-data-microvolt",
lvds_vod_swing_data, ARRAY_SIZE(lvds_vod_swing_data));
if (ret_data != 0 && ret_data != -EINVAL) {
--
2.47.3
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2026-07-09 12:58 [PATCH v2] drm/bridge: ti-sn65dsi83: Add reversed lvds lanes support Wojciech Dubowik
2026-07-09 13:29 ` Laurent Pinchart
2026-07-10 8:01 ` Wojciech Dubowik
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