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

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Message-Id: <20210728094511.3.I842d483139531aa4651da8338512fdf0171ff23c@changeid>
Date:   Wed, 28 Jul 2021 09:45:54 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org
Cc:     tzimmermann@...e.de, linux-arm-msm@...r.kernel.org,
        a.hajda@...sung.com, sam@...nborg.org, airlied@...ux.ie,
        bjorn.andersson@...aro.org, daniel@...ll.ch,
        devicetree@...r.kernel.org, rodrigo.vivi@...el.com,
        jonas@...boo.se, narmstrong@...libre.com,
        Laurent.pinchart@...asonboard.com, robert.foss@...aro.org,
        jernej.skrabec@...il.com, mripard@...nel.org,
        linus.walleij@...aro.org, maarten.lankhorst@...ux.intel.com,
        rajeevny@...eaurora.org, lyude@...hat.com,
        thierry.reding@...il.com, steev@...i.org,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 3/6] drm/bridge: ti-sn65dsi86: Add some 100 us delays

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.

Signed-off-by: Douglas Anderson <dianders@...omium.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 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)
-- 
2.32.0.432.gabb21c7263-goog