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

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Message-Id: <20210730084534.v2.3.I842d483139531aa4651da8338512fdf0171ff23c@changeid>
Date:   Fri, 30 Jul 2021 08:46:02 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org
Cc:     devicetree@...r.kernel.org, steev@...i.org, robert.foss@...aro.org,
        Laurent.pinchart@...asonboard.com, bjorn.andersson@...aro.org,
        daniel@...ll.ch, airlied@...ux.ie, jernej.skrabec@...il.com,
        maarten.lankhorst@...ux.intel.com, rodrigo.vivi@...el.com,
        sam@...nborg.org, jonas@...boo.se, mripard@...nel.org,
        thierry.reding@...il.com, lyude@...hat.com,
        linus.walleij@...aro.org, rajeevny@...eaurora.org,
        linux-arm-msm@...r.kernel.org, a.hajda@...sung.com,
        tzimmermann@...e.de, narmstrong@...libre.com,
        Douglas Anderson <dianders@...omium.org>,
        Sean Paul <seanpaul@...omium.org>,
        Sandeep Panda <spanda@...eaurora.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 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.

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>
---

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