[PATCH 2/2] drm/bridge: adv7533: Add option to disable lane switching

[Biju Das]

On Renesas RZ/{G2L,V2L} platforms changing the lanes from 4 to 3 at
lower frequencies causes display instability. On such platforms, it
is better to avoid switching lanes from 4 to 3 as it needs different
set of PLL parameter constraints to make the display stable with 3
lanes.

This patch adds an option to disable lane switching if
'adi,disable-lanes-override' property is present in DT.

Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
---
 drivers/gpu/drm/bridge/adv7511/adv7511.h | 1 +
 drivers/gpu/drm/bridge/adv7511/adv7533.c | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
index 592ecfcf00ca..7505601f10fb 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
@@ -368,6 +368,7 @@ struct adv7511 {
 	struct mipi_dsi_device *dsi;
 	u8 num_dsi_lanes;
 	bool use_timing_gen;
+	bool override_lanes;
 
 	enum adv7511_type type;
 	struct platform_device *audio_pdev;
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
index eb7579dec40a..7f6a8e95d70e 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
@@ -108,7 +108,7 @@ void adv7533_mode_set(struct adv7511 *adv, const struct drm_display_mode *mode)
 	if (adv->num_dsi_lanes != 4)
 		return;
 
-	if (mode->clock > 80000)
+	if (!adv->override_lanes || mode->clock > 80000)
 		lanes = 4;
 	else
 		lanes = 3;
@@ -195,6 +195,9 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv)
 	adv->use_timing_gen = !of_property_read_bool(np,
 						"adi,disable-timing-generator");
 
+	adv->override_lanes = !of_property_read_bool(np,
+						"adi,disable-lanes-override");
+
 	/* TODO: Check if these need to be parsed by DT or not */
 	adv->rgb = true;
 	adv->embedded_sync = false;
-- 
2.17.1