linux-kernel - [PATCH 5.14 151/334] drm/bridge: ti-sn65dsi86: Add some 100 us delays

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Message-Id: <20210913131118.465891522@linuxfoundation.org>
Date:   Mon, 13 Sep 2021 15:13:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Douglas Anderson <dianders@...omium.org>,
        Robert Foss <robert.foss@...aro.org>,
        Sean Paul <seanpaul@...omium.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 151/334] drm/bridge: ti-sn65dsi86: Add some 100 us delays

From: Douglas Anderson <dianders@...omium.org>

[ Upstream commit e183bf31cf0d3a05162e633e428350ed176ce926 ]

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@...omium.org>
Acked-by: Robert Foss <robert.foss@...aro.org>
Reviewed-by: Sean Paul <seanpaul@...omium.org>
Signed-off-by: Sam Ravnborg <sam@...nborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210730084534.v2.3.I842d483139531aa4651da8338512fdf0171ff23c@changeid
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 ecd4fa3a9a1d..c9cddf317c72 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
@@ -304,6 +304,9 @@ 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);
 
 	/*
@@ -886,6 +889,9 @@ 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)
-- 
2.30.2