Thread (7 messages) flat view 7 messages, 1 author, 2021-07-30
STALE1832d REVIEWED: 2 (0M)

Revision v2 of 2 in this series; 2 review trailers.

Revisions (2)
  1. v1 [diff vs current]
  2. v2 current

[PATCH v2 3/6] drm/bridge: ti-sn65dsi86: Add some 100 us delays

From: Douglas Anderson <dianders@chromium.org>
Date: 2021-07-30 15:46:55
Also in: dri-devel, linux-arm-msm, lkml
Subsystem: drm driver for ti sn65dsi86 bridge chip, drm drivers, drm drivers and misc gpu patches, drm drivers for bridge chips, the rest · Maintainers: David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Andrzej Hajda, Neil Armstrong, Robert Foss, Linus Torvalds

The manual has always said that we need 100 us delays in a few
places. Though it hasn't seemed to be a big deal to skip these, let's
add them in case it makes something happier.

NOTE: this fixes no known issues but it seems good to make it right.

Fixes: a095f15c00e2 ("drm/bridge: add support for sn65dsi86 bridge driver")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Robert Foss <redacted>
Reviewed-by: Sean Paul <redacted>
---

Changes in v2:
- Added Fixes tag as requested by Sam.

 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
index 5e932070a1c3..cd0fccdd8dfd 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -307,6 +307,9 @@ static int __maybe_unused ti_sn65dsi86_resume(struct device *dev)
 		return ret;
 	}
 
+	/* td2: min 100 us after regulators before enabling the GPIO */
+	usleep_range(100, 110);
+
 	gpiod_set_value(pdata->enable_gpio, 1);
 
 	/*
@@ -1096,6 +1099,9 @@ static void ti_sn_bridge_pre_enable(struct drm_bridge *bridge)
 
 	if (!pdata->refclk)
 		ti_sn65dsi86_enable_comms(pdata);
+
+	/* td7: min 100 us after enable before DSI data */
+	usleep_range(100, 110);
 }
 
 static void ti_sn_bridge_post_disable(struct drm_bridge *bridge)
-- 
2.32.0.554.ge1b32706d8-goog
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