[RFC] [PATCH] drm: adv7511/33: Fix adv7511_cec_init() failure handling

[Hans Verkuil]

If the device tree for a board did not specify a cec clock, then
adv7511_cec_init would return an error, which would cause adv7511_probe()
to fail and thus there is no HDMI output.

There is no need to have adv7511_probe() fail if the CEC initialization
fails, so just change adv7511_cec_init() to a void function. In addition,
adv7511_cec_init() should just return silently if the cec clock isn't
found and show a message for any other errors.

An otherwise correct cleanup patch from Dan Carpenter turned this broken
failure handling into a kernel Oops, so bisection points to commit
7af35b0addbc ("drm/kirin: Checking for IS_ERR() instead of NULL") rather
than 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support").

Based on earlier patches from Arnd and John.

Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx>
Cc: Xinliang Liu <xinliang.liu@xxxxxxxxxx>
Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Link: https://bugs.linaro.org/show_bug.cgi?id=3345
Link: https://lkft.validation.linaro.org/scheduler/job/48017#L3551
Fixes: 7af35b0addbc ("drm/kirin: Checking for IS_ERR() instead of NULL")
Fixes: 3b1b975003e4 ("drm: adv7511/33: add HDMI CEC support")
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
This rework of Arnd and John's patches goes a bit further and makes
cec_init a void function and just silently exits if there is no cec clock
defined in the dts. I'm sure that's the reason why the kirin board failed
on this. BTW: if the kirin board DOES support cec, then it would be nice
if it can be hooked up in the dts!

I'll test this with my two adv7511/33 boards on Monday.

Regards,

	Hans
---
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
index 543a5eb91624..bc17aa965e58 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
@@ -374,8 +374,8 @@ struct adv7511 {
 };

 #ifdef CONFIG_DRM_I2C_ADV7511_CEC
-int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511,
-		     unsigned int offset);
+void adv7511_cec_init(struct device *dev, struct adv7511 *adv7511,
+		      unsigned int offset);
 void adv7511_cec_irq_process(struct adv7511 *adv7511, unsigned int irq1);
 #endif

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
index b33d730e4d73..c1cd471d31fa 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_cec.c
@@ -300,18 +300,20 @@ static int adv7511_cec_parse_dt(struct device *dev, struct adv7511 *adv7511)
 	return 0;
 }

-int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511,
-		     unsigned int offset)
+void adv7511_cec_init(struct device *dev, struct adv7511 *adv7511,
+		      unsigned int offset)
 {
 	int ret = adv7511_cec_parse_dt(dev, adv7511);

 	if (ret)
-		return ret;
+		goto disable_cec;

 	adv7511->cec_adap = cec_allocate_adapter(&adv7511_cec_adap_ops,
 		adv7511, dev_name(dev), CEC_CAP_DEFAULTS, ADV7511_MAX_ADDRS);
-	if (IS_ERR(adv7511->cec_adap))
-		return PTR_ERR(adv7511->cec_adap);
+	if (IS_ERR(adv7511->cec_adap)) {
+		ret = PTR_ERR(adv7511->cec_adap);
+		goto fail;
+	}

 	regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset, 0);
 	/* cec soft reset */
@@ -329,9 +331,15 @@ int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511,
 		     ((adv7511->cec_clk_freq / 750000) - 1) << 2);

 	ret = cec_register_adapter(adv7511->cec_adap, dev);
-	if (ret) {
-		cec_delete_adapter(adv7511->cec_adap);
-		adv7511->cec_adap = NULL;
-	}
-	return ret;
+	if (!ret)
+		return;
+	cec_delete_adapter(adv7511->cec_adap);
+	adv7511->cec_adap = NULL;
+
+fail:
+	dev_info(dev, "Initializing CEC failed with error %d, disabling CEC\n",
+		 ret);
+disable_cec:
+	regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
+		     ADV7511_CEC_CTRL_POWER_DOWN);
 }
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index 3a33075dbb22..56eeeea6a1fa 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1202,9 +1202,7 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 	offset = adv7511->type == ADV7533 ? ADV7533_REG_CEC_OFFSET : 0;

 #ifdef CONFIG_DRM_I2C_ADV7511_CEC
-	ret = adv7511_cec_init(dev, adv7511, offset);
-	if (ret)
-		goto err_unregister_cec;
+	adv7511_cec_init(dev, adv7511, offset);
 #else
 	regmap_write(adv7511->regmap, ADV7511_REG_CEC_CTRL + offset,
 		     ADV7511_CEC_CTRL_POWER_DOWN);