[PATCH 0/2] More meson HDMI fixes

[PATCH 0/2] More meson HDMI fixes

[Marc Zyngier]

Guillaume reported that my earlier fixes for the meson HDMI driver
broke another set of machines which are now exploding (clock not
enabled).

I have thus reconsidered the approach and came up with an alternative
fix (enable a missing clock), which Guillaume confirmed to be working.
Jerome pointed out that this driver is leaking clock references like a
sieve, so that needed addressing too.

The first patch start by fixing the clock leakage using a devm
facility.

The second patch addresses the earlier crash by reusing the
infrastructure put together in the first patch.

Tested on VIM3l.

Marc Zyngier (2):
  drm/meson: dw-hdmi: Disable clocks on driver teardown
  drm/meson: dw-hdmi: Enable the iahb clock early enough

 drivers/gpu/drm/meson/meson_dw_hdmi.c | 51 ++++++++++++++++++---------
 1 file changed, 35 insertions(+), 16 deletions(-)

-- 
2.28.0

[PATCH 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown

[Marc Zyngier]

The HDMI driver request clocks early, but never disable them, leaving
the clocks on even when the driver is removed.

Fix it by slightly refactoring the clock code, and register a devm
action that will eventually disable/unprepare the enabled clocks.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/gpu/drm/meson/meson_dw_hdmi.c | 43 ++++++++++++++++++---------
 1 file changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
index 7f8eea494147..29623b309cb1 100644
--- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
@@ -145,8 +145,6 @@ struct meson_dw_hdmi {
 	struct reset_control *hdmitx_apb;
 	struct reset_control *hdmitx_ctrl;
 	struct reset_control *hdmitx_phy;
-	struct clk *hdmi_pclk;
-	struct clk *venci_clk;
 	struct regulator *hdmi_supply;
 	u32 irq_stat;
 	struct dw_hdmi *hdmi;
@@ -946,6 +944,29 @@ static void meson_disable_regulator(void *data)
 	regulator_disable(data);
 }
 
+static void meson_disable_clk(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
+static int meson_enable_clk(struct device *dev, char *name)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = devm_clk_get(dev, name);
+	if (IS_ERR(clk)) {
+		dev_err(dev, "Unable to get %s pclk\n", name);
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (!ret)
+		ret = devm_add_action_or_reset(dev, meson_disable_clk, clk);
+
+	return ret;
+}
+
 static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 				void *data)
 {
@@ -1026,19 +1047,13 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 	if (IS_ERR(meson_dw_hdmi->hdmitx))
 		return PTR_ERR(meson_dw_hdmi->hdmitx);
 
-	meson_dw_hdmi->hdmi_pclk = devm_clk_get(dev, "isfr");
-	if (IS_ERR(meson_dw_hdmi->hdmi_pclk)) {
-		dev_err(dev, "Unable to get HDMI pclk\n");
-		return PTR_ERR(meson_dw_hdmi->hdmi_pclk);
-	}
-	clk_prepare_enable(meson_dw_hdmi->hdmi_pclk);
+	ret = meson_enable_clk(dev, "isfr");
+	if (ret)
+		return ret;
 
-	meson_dw_hdmi->venci_clk = devm_clk_get(dev, "venci");
-	if (IS_ERR(meson_dw_hdmi->venci_clk)) {
-		dev_err(dev, "Unable to get venci clk\n");
-		return PTR_ERR(meson_dw_hdmi->venci_clk);
-	}
-	clk_prepare_enable(meson_dw_hdmi->venci_clk);
+	ret = meson_enable_clk(dev, "venci");
+	if (ret)
+		return ret;
 
 	dw_plat_data->regm = devm_regmap_init(dev, NULL, meson_dw_hdmi,
 					      &meson_dw_hdmi_regmap_config);
-- 
2.28.0

[PATCH 2/2] drm/meson: dw-hdmi: Enable the iahb clock early enough

[Marc Zyngier]

Instead of moving meson_dw_hdmi_init() around which breaks existing
platform, let's enable the clock meson_dw_hdmi_init() depends on.
This means we don't have to worry about this clock being enabled or
not, depending on the boot-loader features.

Fixes: b33340e33acd ("drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers")
Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Tested-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/gpu/drm/meson/meson_dw_hdmi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
index 29623b309cb1..aad75a22dc33 100644
--- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
@@ -1051,6 +1051,10 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 	if (ret)
 		return ret;
 
+	ret = meson_enable_clk(dev, "iahb");
+	if (ret)
+		return ret;
+
 	ret = meson_enable_clk(dev, "venci");
 	if (ret)
 		return ret;
@@ -1086,6 +1090,8 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 
 	encoder->possible_crtcs = BIT(0);
 
+	meson_dw_hdmi_init(meson_dw_hdmi);
+
 	DRM_DEBUG_DRIVER("encoder initialized\n");
 
 	/* Bridge / Connector */
@@ -1110,8 +1116,6 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
 	if (IS_ERR(meson_dw_hdmi->hdmi))
 		return PTR_ERR(meson_dw_hdmi->hdmi);
 
-	meson_dw_hdmi_init(meson_dw_hdmi);
-
 	next_bridge = of_drm_find_bridge(pdev->dev.of_node);
 	if (next_bridge)
 		drm_bridge_attach(encoder, next_bridge,
-- 
2.28.0

Re: [PATCH 2/2] drm/meson: dw-hdmi: Enable the iahb clock early enough

[Guillaume Tucker]

On 20/11/2020 09:42, Marc Zyngier wrote:
> Instead of moving meson_dw_hdmi_init() around which breaks existing
> platform, let's enable the clock meson_dw_hdmi_init() depends on.
> This means we don't have to worry about this clock being enabled or
> not, depending on the boot-loader features.
> 
> Fixes: b33340e33acd ("drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers")
> Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>

Although I am triaging kernelci bisections, it was initially
found thanks to our friendly bot.  So if you're OK with this, it
would most definitely appreciate a mention:

  Reported-by: "kernelci.org bot" <bot@kernelci.org>

Thanks,
Guillaume

Re: [PATCH 2/2] drm/meson: dw-hdmi: Enable the iahb clock early enough

[Marc Zyngier]

On 2020-11-20 10:54, Guillaume Tucker wrote:
> On 20/11/2020 09:42, Marc Zyngier wrote:
>> Instead of moving meson_dw_hdmi_init() around which breaks existing
>> platform, let's enable the clock meson_dw_hdmi_init() depends on.
>> This means we don't have to worry about this clock being enabled or
>> not, depending on the boot-loader features.
>> 
>> Fixes: b33340e33acd ("drm/meson: dw-hdmi: Ensure that clocks are 
>> enabled before touching the TOP registers")
>> Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>
> 
> Although I am triaging kernelci bisections, it was initially
> found thanks to our friendly bot.  So if you're OK with this, it
> would most definitely appreciate a mention:
> 
>   Reported-by: "kernelci.org bot" <bot@kernelci.org>

Sure. Neil can add this when (and if) he applies these patches.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH 2/2] drm/meson: dw-hdmi: Enable the iahb clock early enough

[Neil Armstrong]

On 20/11/2020 12:10, Marc Zyngier wrote:
> On 2020-11-20 10:54, Guillaume Tucker wrote:
>> On 20/11/2020 09:42, Marc Zyngier wrote:
>>> Instead of moving meson_dw_hdmi_init() around which breaks existing
>>> platform, let's enable the clock meson_dw_hdmi_init() depends on.
>>> This means we don't have to worry about this clock being enabled or
>>> not, depending on the boot-loader features.
>>>
>>> Fixes: b33340e33acd ("drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers")
>>> Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>
>>
>> Although I am triaging kernelci bisections, it was initially
>> found thanks to our friendly bot.  So if you're OK with this, it
>> would most definitely appreciate a mention:
>>
>>   Reported-by: "kernelci.org bot" <bot@kernelci.org>
> 
> Sure. Neil can add this when (and if) he applies these patches.

Yep applying to drm-misc-next and switching to `Reported-by: "kernelci.org bot" <bot@kernelci.org>`

Thanks
Neil

> 
> Thanks,
> 
>         M.

Re: [PATCH 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown

[Neil Armstrong]

On 20/11/2020 10:42, Marc Zyngier wrote:
> The HDMI driver request clocks early, but never disable them, leaving
> the clocks on even when the driver is removed.
> 
> Fix it by slightly refactoring the clock code, and register a devm
> action that will eventually disable/unprepare the enabled clocks.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 43 ++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 7f8eea494147..29623b309cb1 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -145,8 +145,6 @@ struct meson_dw_hdmi {
>  	struct reset_control *hdmitx_apb;
>  	struct reset_control *hdmitx_ctrl;
>  	struct reset_control *hdmitx_phy;
> -	struct clk *hdmi_pclk;
> -	struct clk *venci_clk;
>  	struct regulator *hdmi_supply;
>  	u32 irq_stat;
>  	struct dw_hdmi *hdmi;
> @@ -946,6 +944,29 @@ static void meson_disable_regulator(void *data)
>  	regulator_disable(data);
>  }
>  
> +static void meson_disable_clk(void *data)
> +{
> +	clk_disable_unprepare(data);
> +}
> +
> +static int meson_enable_clk(struct device *dev, char *name)
> +{
> +	struct clk *clk;
> +	int ret;
> +
> +	clk = devm_clk_get(dev, name);
> +	if (IS_ERR(clk)) {
> +		dev_err(dev, "Unable to get %s pclk\n", name);
> +		return PTR_ERR(clk);
> +	}
> +
> +	ret = clk_prepare_enable(clk);
> +	if (!ret)
> +		ret = devm_add_action_or_reset(dev, meson_disable_clk, clk);
> +
> +	return ret;
> +}
> +
>  static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  				void *data)
>  {
> @@ -1026,19 +1047,13 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  	if (IS_ERR(meson_dw_hdmi->hdmitx))
>  		return PTR_ERR(meson_dw_hdmi->hdmitx);
>  
> -	meson_dw_hdmi->hdmi_pclk = devm_clk_get(dev, "isfr");
> -	if (IS_ERR(meson_dw_hdmi->hdmi_pclk)) {
> -		dev_err(dev, "Unable to get HDMI pclk\n");
> -		return PTR_ERR(meson_dw_hdmi->hdmi_pclk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->hdmi_pclk);
> +	ret = meson_enable_clk(dev, "isfr");
> +	if (ret)
> +		return ret;
>  
> -	meson_dw_hdmi->venci_clk = devm_clk_get(dev, "venci");
> -	if (IS_ERR(meson_dw_hdmi->venci_clk)) {
> -		dev_err(dev, "Unable to get venci clk\n");
> -		return PTR_ERR(meson_dw_hdmi->venci_clk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->venci_clk);
> +	ret = meson_enable_clk(dev, "venci");
> +	if (ret)
> +		return ret;
>  
>  	dw_plat_data->regm = devm_regmap_init(dev, NULL, meson_dw_hdmi,
>  					      &meson_dw_hdmi_regmap_config);
> 

Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Re: [PATCH 2/2] drm/meson: dw-hdmi: Enable the iahb clock early enough

[Neil Armstrong]

On 20/11/2020 10:42, Marc Zyngier wrote:
> Instead of moving meson_dw_hdmi_init() around which breaks existing
> platform, let's enable the clock meson_dw_hdmi_init() depends on.
> This means we don't have to worry about this clock being enabled or
> not, depending on the boot-loader features.
> 
> Fixes: b33340e33acd ("drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers")
> Reported-by: Guillaume Tucker <guillaume.tucker@collabora.com>
> Tested-by: Guillaume Tucker <guillaume.tucker@collabora.com>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 29623b309cb1..aad75a22dc33 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -1051,6 +1051,10 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  	if (ret)
>  		return ret;
>  
> +	ret = meson_enable_clk(dev, "iahb");
> +	if (ret)
> +		return ret;
> +
>  	ret = meson_enable_clk(dev, "venci");
>  	if (ret)
>  		return ret;
> @@ -1086,6 +1090,8 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  
>  	encoder->possible_crtcs = BIT(0);
>  
> +	meson_dw_hdmi_init(meson_dw_hdmi);
> +
>  	DRM_DEBUG_DRIVER("encoder initialized\n");
>  
>  	/* Bridge / Connector */
> @@ -1110,8 +1116,6 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  	if (IS_ERR(meson_dw_hdmi->hdmi))
>  		return PTR_ERR(meson_dw_hdmi->hdmi);
>  
> -	meson_dw_hdmi_init(meson_dw_hdmi);
> -
>  	next_bridge = of_drm_find_bridge(pdev->dev.of_node);
>  	if (next_bridge)
>  		drm_bridge_attach(encoder, next_bridge,
> 
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>

Re: [PATCH 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown

[Jerome Brunet]

On Fri 20 Nov 2020 at 10:42, Marc Zyngier <maz@kernel.org> wrote:

> The HDMI driver request clocks early, but never disable them, leaving
> the clocks on even when the driver is removed.
>
> Fix it by slightly refactoring the clock code, and register a devm
> action that will eventually disable/unprepare the enabled clocks.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 43 ++++++++++++++++++---------
>  1 file changed, 29 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 7f8eea494147..29623b309cb1 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -145,8 +145,6 @@ struct meson_dw_hdmi {
>  	struct reset_control *hdmitx_apb;
>  	struct reset_control *hdmitx_ctrl;
>  	struct reset_control *hdmitx_phy;
> -	struct clk *hdmi_pclk;
> -	struct clk *venci_clk;
>  	struct regulator *hdmi_supply;
>  	u32 irq_stat;
>  	struct dw_hdmi *hdmi;
> @@ -946,6 +944,29 @@ static void meson_disable_regulator(void *data)
>  	regulator_disable(data);
>  }
>  
> +static void meson_disable_clk(void *data)
> +{
> +	clk_disable_unprepare(data);
> +}
> +
> +static int meson_enable_clk(struct device *dev, char *name)
> +{
> +	struct clk *clk;
> +	int ret;
> +
> +	clk = devm_clk_get(dev, name);
> +	if (IS_ERR(clk)) {
> +		dev_err(dev, "Unable to get %s pclk\n", name);
> +		return PTR_ERR(clk);
> +	}
> +
> +	ret = clk_prepare_enable(clk);
> +	if (!ret)
> +		ret = devm_add_action_or_reset(dev, meson_disable_clk,
> clk);

Thanks for fixing this Marc.

FYI, while it is fine to declare a function to disable the clocks, a quick
cast may avoid it

devm_add_action_or_reset(dev, (void(*)(void *))clk_disable_unprepare, clk);

> +
> +	return ret;
> +}
> +
>  static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  				void *data)
>  {
> @@ -1026,19 +1047,13 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>  	if (IS_ERR(meson_dw_hdmi->hdmitx))
>  		return PTR_ERR(meson_dw_hdmi->hdmitx);
>  
> -	meson_dw_hdmi->hdmi_pclk = devm_clk_get(dev, "isfr");
> -	if (IS_ERR(meson_dw_hdmi->hdmi_pclk)) {
> -		dev_err(dev, "Unable to get HDMI pclk\n");
> -		return PTR_ERR(meson_dw_hdmi->hdmi_pclk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->hdmi_pclk);
> +	ret = meson_enable_clk(dev, "isfr");
> +	if (ret)
> +		return ret;
>  
> -	meson_dw_hdmi->venci_clk = devm_clk_get(dev, "venci");
> -	if (IS_ERR(meson_dw_hdmi->venci_clk)) {
> -		dev_err(dev, "Unable to get venci clk\n");
> -		return PTR_ERR(meson_dw_hdmi->venci_clk);
> -	}
> -	clk_prepare_enable(meson_dw_hdmi->venci_clk);
> +	ret = meson_enable_clk(dev, "venci");
> +	if (ret)
> +		return ret;
>  
>  	dw_plat_data->regm = devm_regmap_init(dev, NULL, meson_dw_hdmi,
>  					      &meson_dw_hdmi_regmap_config);

Re: [PATCH 1/2] drm/meson: dw-hdmi: Disable clocks on driver teardown

[Marc Zyngier]

On 2020-11-23 14:03, Jerome Brunet wrote:
> On Fri 20 Nov 2020 at 10:42, Marc Zyngier <maz@kernel.org> wrote:
> 
>> The HDMI driver request clocks early, but never disable them, leaving
>> the clocks on even when the driver is removed.
>> 
>> Fix it by slightly refactoring the clock code, and register a devm
>> action that will eventually disable/unprepare the enabled clocks.
>> 
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 43 
>> ++++++++++++++++++---------
>>  1 file changed, 29 insertions(+), 14 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c 
>> b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> index 7f8eea494147..29623b309cb1 100644
>> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> @@ -145,8 +145,6 @@ struct meson_dw_hdmi {
>>  	struct reset_control *hdmitx_apb;
>>  	struct reset_control *hdmitx_ctrl;
>>  	struct reset_control *hdmitx_phy;
>> -	struct clk *hdmi_pclk;
>> -	struct clk *venci_clk;
>>  	struct regulator *hdmi_supply;
>>  	u32 irq_stat;
>>  	struct dw_hdmi *hdmi;
>> @@ -946,6 +944,29 @@ static void meson_disable_regulator(void *data)
>>  	regulator_disable(data);
>>  }
>> 
>> +static void meson_disable_clk(void *data)
>> +{
>> +	clk_disable_unprepare(data);
>> +}
>> +
>> +static int meson_enable_clk(struct device *dev, char *name)
>> +{
>> +	struct clk *clk;
>> +	int ret;
>> +
>> +	clk = devm_clk_get(dev, name);
>> +	if (IS_ERR(clk)) {
>> +		dev_err(dev, "Unable to get %s pclk\n", name);
>> +		return PTR_ERR(clk);
>> +	}
>> +
>> +	ret = clk_prepare_enable(clk);
>> +	if (!ret)
>> +		ret = devm_add_action_or_reset(dev, meson_disable_clk,
>> clk);
> 
> Thanks for fixing this Marc.
> 
> FYI, while it is fine to declare a function to disable the clocks, a 
> quick
> cast may avoid it
> 
> devm_add_action_or_reset(dev, (void(*)(void *))clk_disable_unprepare, 
> clk);

While this works for now, a change to the clk_disable_unprepare()
prototype (such as adding a second argument) would now go completely
unnoticed (after all, you've cast the function, it *must* be correct,
right?), and someone would spend a few hours trying to track down memory
corruption or some other interesting results.

Yes, casting C functions can be hilarious.

I can see a few uses of this hack in the tree, and I have my pop-corn
ready.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...