linux-kernel - [PATCH] drm: adv7511: override i2c address of cec before accessing it

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Message-ID: <20211218182804.208906-1-antonio.borneo@foss.st.com>
Date:   Sat, 18 Dec 2021 19:28:04 +0100
From:   Antonio Borneo <antonio.borneo@...s.st.com>
To:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        <dri-devel@...ts.freedesktop.org>
CC:     Antonio Borneo <antonio.borneo@...s.st.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>
Subject: [PATCH] drm: adv7511: override i2c address of cec before accessing it

Commit 680532c50bca ("drm: adv7511: Add support for
i2c_new_secondary_device") allows a device tree node to override
the default addresses of the secondary i2c devices. This is useful
for solving address conflicts on the i2c bus.

In adv7511_init_cec_regmap() the new i2c address of cec device is
read from device tree and immediately accessed, well before it is
written in the proper register to override the default address.
This can cause an i2c error during probe and a consequent probe
failure.

Once the new i2c address is read from the device tree, override
the default address before any attempt to access the cec.

Tested with adv7533 and stm32mp157f.

Signed-off-by: Antonio Borneo <antonio.borneo@...s.st.com>
Fixes: 680532c50bca ("drm: adv7511: Add support for i2c_new_secondary_device")
---
To: Andrzej Hajda <a.hajda@...sung.com>
To: Neil Armstrong <narmstrong@...libre.com>
To: Robert Foss <robert.foss@...aro.org>
To: Laurent Pinchart <Laurent.pinchart@...asonboard.com>
To: Jonas Karlman <jonas@...boo.se>
To: Jernej Skrabec <jernej.skrabec@...il.com>
To: David Airlie <airlied@...ux.ie>
To: Daniel Vetter <daniel@...ll.ch>
To: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
To: dri-devel@...ts.freedesktop.org
Cc: linux-kernel@...r.kernel.org
Cc: linux-stm32@...md-mailman.stormreply.com
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 76555ae64e9c..629e05286fd9 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1048,6 +1048,10 @@ static int adv7511_init_cec_regmap(struct adv7511 *adv)
 						ADV7511_CEC_I2C_ADDR_DEFAULT);
 	if (IS_ERR(adv->i2c_cec))
 		return PTR_ERR(adv->i2c_cec);
+
+	regmap_write(adv->regmap, ADV7511_REG_CEC_I2C_ADDR,
+		     adv->i2c_cec->addr << 1);
+
 	i2c_set_clientdata(adv->i2c_cec, adv);
 
 	adv->regmap_cec = devm_regmap_init_i2c(adv->i2c_cec,
@@ -1252,9 +1256,6 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 	if (ret)
 		goto err_i2c_unregister_packet;
 
-	regmap_write(adv7511->regmap, ADV7511_REG_CEC_I2C_ADDR,
-		     adv7511->i2c_cec->addr << 1);
-
 	INIT_WORK(&adv7511->hpd_work, adv7511_hpd_work);
 
 	if (i2c->irq) {

base-commit: fc74881c28d314b10efac016ef49df4ff40b8b97
-- 
2.34.1