[PATCH v2 0/2] ASoC hdmi-codec: fix HDMI jack reporting

[PATCH v2 0/2] ASoC hdmi-codec: fix HDMI jack reporting

[Tzung-Bi Shih]

With proper unbinding audio components and inserting the HDMI external
display, kernel crashes as the following messages:

Unable to handle kernel NULL pointer dereference at virtual address ...
[snip]
Call trace:
 plugged_cb+0x1c/0x74
 mtk_hdmi_update_plugged_status+0x48/0x6c
 hdmi_conn_detect+0x1c/0x28
 drm_helper_probe_detect+0x110/0x170
 drm_helper_probe_single_connector_modes+0xd4/0x608
 drm_mode_getconnector+0x1e8/0x418

The 1st patch fixes the crash by notifying hdmi-codec's consumers to not
report jack status anymore when component removing.

The 2nd patch fixes race condition in mediatek/mtk_hdmi.c.

Changes from v1:
(https://patchwork.kernel.org/patch/11379979/)
- added the 1st patch
- use mutex to protect plugged_cb and codec_dev in 2nd patch

Tzung-Bi Shih (2):
  ASoC: hdmi-codec: set plugged_cb to NULL when component removing
  drm/mediatek: fix race condition for HDMI jack status reporting

 drivers/gpu/drm/mediatek/mtk_hdmi.c | 11 ++++++++++-
 sound/soc/codecs/hdmi-codec.c       | 10 ++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

-- 
2.25.0.265.gbab2e86ba0-goog


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[PATCH v2 1/2] ASoC: hdmi-codec: set plugged_cb to NULL when component removing

[Tzung-Bi Shih]

Sets plugged_cb to NULL when component removing to notify its consumers
: no further plugged status report is required.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
---
 sound/soc/codecs/hdmi-codec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index 444cc4e3374e..f005751da2cc 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -779,7 +779,17 @@ static int hdmi_of_xlate_dai_id(struct snd_soc_component *component,
 	return ret;
 }
 
+static void hdmi_remove(struct snd_soc_component *component)
+{
+	struct hdmi_codec_priv *hcp = snd_soc_component_get_drvdata(component);
+
+	if (hcp->hcd.ops->hook_plugged_cb)
+		hcp->hcd.ops->hook_plugged_cb(component->dev->parent,
+					      hcp->hcd.data, NULL, NULL);
+}
+
 static const struct snd_soc_component_driver hdmi_driver = {
+	.remove			= hdmi_remove,
 	.dapm_widgets		= hdmi_widgets,
 	.num_dapm_widgets	= ARRAY_SIZE(hdmi_widgets),
 	.of_xlate_dai_id	= hdmi_of_xlate_dai_id,
-- 
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[PATCH v2 2/2] drm/mediatek: fix race condition for HDMI jack status reporting

[Tzung-Bi Shih]

hdmi_conn_detect and mtk_hdmi_audio_hook_plugged_cb would be called
by different threads.

Imaging the following calling sequence:
           Thread A                            Thread B
--------------------------------------------------------------------
mtk_hdmi_audio_hook_plugged_cb()
mtk_cec_hpd_high() -> disconnected
                                     hdmi_conn_detect()
                                     mtk_cec_hpd_high() -> connected
                                     plugged_cb(connected)
plugged_cb(disconnected)

The latest disconnected is false reported.  Makes mtk_cec_hpd_high
and plugged_cb atomic to fix.

Also uses the same lock to protect read/write of plugged_cb and codec_dev.

Fixes: 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting")
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
---
 drivers/gpu/drm/mediatek/mtk_hdmi.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index 03aeb73005ef..d80017e3d84a 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -12,6 +12,7 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
+#include <linux/mutex.h>
 #include <linux/of_platform.h>
 #include <linux/of.h>
 #include <linux/of_gpio.h>
@@ -171,6 +172,7 @@ struct mtk_hdmi {
 	bool enabled;
 	hdmi_codec_plugged_cb plugged_cb;
 	struct device *codec_dev;
+	struct mutex update_plugged_status_lock;
 };
 
 static inline struct mtk_hdmi *hdmi_ctx_from_bridge(struct drm_bridge *b)
@@ -1199,10 +1201,13 @@ static void mtk_hdmi_clk_disable_audio(struct mtk_hdmi *hdmi)
 static enum drm_connector_status
 mtk_hdmi_update_plugged_status(struct mtk_hdmi *hdmi)
 {
-	bool connected = mtk_cec_hpd_high(hdmi->cec_dev);
+	bool connected;
 
+	mutex_lock(&hdmi->update_plugged_status_lock);
+	connected = mtk_cec_hpd_high(hdmi->cec_dev);
 	if (hdmi->plugged_cb && hdmi->codec_dev)
 		hdmi->plugged_cb(hdmi->codec_dev, connected);
+	mutex_unlock(&hdmi->update_plugged_status_lock);
 
 	return connected ?
 	       connector_status_connected : connector_status_disconnected;
@@ -1669,8 +1674,11 @@ static int mtk_hdmi_audio_hook_plugged_cb(struct device *dev, void *data,
 {
 	struct mtk_hdmi *hdmi = data;
 
+	mutex_lock(&hdmi->update_plugged_status_lock);
 	hdmi->plugged_cb = fn;
 	hdmi->codec_dev = codec_dev;
+	mutex_unlock(&hdmi->update_plugged_status_lock);
+
 	mtk_hdmi_update_plugged_status(hdmi);
 
 	return 0;
@@ -1729,6 +1737,7 @@ static int mtk_drm_hdmi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	mutex_init(&hdmi->update_plugged_status_lock);
 	platform_set_drvdata(pdev, hdmi);
 
 	ret = mtk_hdmi_output_init(hdmi);
-- 
2.25.0.265.gbab2e86ba0-goog


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Re: [PATCH v2 2/2] drm/mediatek: fix race condition for HDMI jack status reporting

[CK Hu]

Hi, Tzhung-Bi:

On Mon, 2020-02-17 at 11:16 +0800, Tzung-Bi Shih wrote:
> hdmi_conn_detect and mtk_hdmi_audio_hook_plugged_cb would be called
> by different threads.
> 
> Imaging the following calling sequence:
>            Thread A                            Thread B
> --------------------------------------------------------------------
> mtk_hdmi_audio_hook_plugged_cb()
> mtk_cec_hpd_high() -> disconnected
>                                      hdmi_conn_detect()
>                                      mtk_cec_hpd_high() -> connected
>                                      plugged_cb(connected)
> plugged_cb(disconnected)
> 
> The latest disconnected is false reported.  Makes mtk_cec_hpd_high
> and plugged_cb atomic to fix.
> 
> Also uses the same lock to protect read/write of plugged_cb and codec_dev.
> 
> Fixes: 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting")

This patch looks good to me, but please merge this patch with the patch
it fix.

Regards,
CK

> Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> index 03aeb73005ef..d80017e3d84a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
> @@ -12,6 +12,7 @@
>  #include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/mfd/syscon.h>
> +#include <linux/mutex.h>
>  #include <linux/of_platform.h>
>  #include <linux/of.h>
>  #include <linux/of_gpio.h>
> @@ -171,6 +172,7 @@ struct mtk_hdmi {
>  	bool enabled;
>  	hdmi_codec_plugged_cb plugged_cb;
>  	struct device *codec_dev;
> +	struct mutex update_plugged_status_lock;
>  };
>  
>  static inline struct mtk_hdmi *hdmi_ctx_from_bridge(struct drm_bridge *b)
> @@ -1199,10 +1201,13 @@ static void mtk_hdmi_clk_disable_audio(struct mtk_hdmi *hdmi)
>  static enum drm_connector_status
>  mtk_hdmi_update_plugged_status(struct mtk_hdmi *hdmi)
>  {
> -	bool connected = mtk_cec_hpd_high(hdmi->cec_dev);
> +	bool connected;
>  
> +	mutex_lock(&hdmi->update_plugged_status_lock);
> +	connected = mtk_cec_hpd_high(hdmi->cec_dev);
>  	if (hdmi->plugged_cb && hdmi->codec_dev)
>  		hdmi->plugged_cb(hdmi->codec_dev, connected);
> +	mutex_unlock(&hdmi->update_plugged_status_lock);
>  
>  	return connected ?
>  	       connector_status_connected : connector_status_disconnected;
> @@ -1669,8 +1674,11 @@ static int mtk_hdmi_audio_hook_plugged_cb(struct device *dev, void *data,
>  {
>  	struct mtk_hdmi *hdmi = data;
>  
> +	mutex_lock(&hdmi->update_plugged_status_lock);
>  	hdmi->plugged_cb = fn;
>  	hdmi->codec_dev = codec_dev;
> +	mutex_unlock(&hdmi->update_plugged_status_lock);
> +
>  	mtk_hdmi_update_plugged_status(hdmi);
>  
>  	return 0;
> @@ -1729,6 +1737,7 @@ static int mtk_drm_hdmi_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	mutex_init(&hdmi->update_plugged_status_lock);
>  	platform_set_drvdata(pdev, hdmi);
>  
>  	ret = mtk_hdmi_output_init(hdmi);

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Re: [PATCH v2 2/2] drm/mediatek: fix race condition for HDMI jack status reporting

[Tzung-Bi Shih]

On Mon, Feb 17, 2020 at 11:44 AM CK Hu <ck.hu@mediatek.com> wrote:
> On Mon, 2020-02-17 at 11:16 +0800, Tzung-Bi Shih wrote:
> > Fixes: 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting")
>
> This patch looks good to me, but please merge this patch with the patch
> it fix.

5d3c64477392 ("drm/mediatek: support HDMI jack status reporting") has
applied to ASoC for-next branch.  This is a fixup patch.

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Re: [PATCH v2 2/2] drm/mediatek: fix race condition for HDMI jack status reporting

[CK Hu]

On Mon, 2020-02-17 at 11:55 +0800, Tzung-Bi Shih wrote:
> On Mon, Feb 17, 2020 at 11:44 AM CK Hu <ck.hu@mediatek.com> wrote:
> > On Mon, 2020-02-17 at 11:16 +0800, Tzung-Bi Shih wrote:
> > > Fixes: 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting")
> >
> > This patch looks good to me, but please merge this patch with the patch
> > it fix.
> 
> 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting") has
> applied to ASoC for-next branch.  This is a fixup patch.

I thought a patch need an ack by the maintainer. OK, so I could do is,
for this patch,

Acked-by: CK Hu <ck.hu@mediatek.com> 
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Applied "drm/mediatek: fix race condition for HDMI jack status reporting" to the asoc tree

[Mark Brown]

The patch

   drm/mediatek: fix race condition for HDMI jack status reporting

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From f07980d4ed60fbb35857b655c94b111f4ddf2abf Mon Sep 17 00:00:00 2001
From: Tzung-Bi Shih <tzungbi@google.com>
Date: Mon, 17 Feb 2020 11:16:53 +0800
Subject: [PATCH] drm/mediatek: fix race condition for HDMI jack status
 reporting

hdmi_conn_detect and mtk_hdmi_audio_hook_plugged_cb would be called
by different threads.

Imaging the following calling sequence:
           Thread A                            Thread B
--------------------------------------------------------------------
mtk_hdmi_audio_hook_plugged_cb()
mtk_cec_hpd_high() -> disconnected
                                     hdmi_conn_detect()
                                     mtk_cec_hpd_high() -> connected
                                     plugged_cb(connected)
plugged_cb(disconnected)

The latest disconnected is false reported.  Makes mtk_cec_hpd_high
and plugged_cb atomic to fix.

Also uses the same lock to protect read/write of plugged_cb and codec_dev.

Fixes: 5d3c64477392 ("drm/mediatek: support HDMI jack status reporting")
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Acked-by: CK Hu <ck.hu@mediatek.com>
Link: https://lore.kernel.org/r/20200217105513.2.I477092c2f104fd589133436c3ae4590e6fc6323b@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/gpu/drm/mediatek/mtk_hdmi.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index 03aeb73005ef..d80017e3d84a 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -12,6 +12,7 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/mfd/syscon.h>
+#include <linux/mutex.h>
 #include <linux/of_platform.h>
 #include <linux/of.h>
 #include <linux/of_gpio.h>
@@ -171,6 +172,7 @@ struct mtk_hdmi {
 	bool enabled;
 	hdmi_codec_plugged_cb plugged_cb;
 	struct device *codec_dev;
+	struct mutex update_plugged_status_lock;
 };
 
 static inline struct mtk_hdmi *hdmi_ctx_from_bridge(struct drm_bridge *b)
@@ -1199,10 +1201,13 @@ static void mtk_hdmi_clk_disable_audio(struct mtk_hdmi *hdmi)
 static enum drm_connector_status
 mtk_hdmi_update_plugged_status(struct mtk_hdmi *hdmi)
 {
-	bool connected = mtk_cec_hpd_high(hdmi->cec_dev);
+	bool connected;
 
+	mutex_lock(&hdmi->update_plugged_status_lock);
+	connected = mtk_cec_hpd_high(hdmi->cec_dev);
 	if (hdmi->plugged_cb && hdmi->codec_dev)
 		hdmi->plugged_cb(hdmi->codec_dev, connected);
+	mutex_unlock(&hdmi->update_plugged_status_lock);
 
 	return connected ?
 	       connector_status_connected : connector_status_disconnected;
@@ -1669,8 +1674,11 @@ static int mtk_hdmi_audio_hook_plugged_cb(struct device *dev, void *data,
 {
 	struct mtk_hdmi *hdmi = data;
 
+	mutex_lock(&hdmi->update_plugged_status_lock);
 	hdmi->plugged_cb = fn;
 	hdmi->codec_dev = codec_dev;
+	mutex_unlock(&hdmi->update_plugged_status_lock);
+
 	mtk_hdmi_update_plugged_status(hdmi);
 
 	return 0;
@@ -1729,6 +1737,7 @@ static int mtk_drm_hdmi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	mutex_init(&hdmi->update_plugged_status_lock);
 	platform_set_drvdata(pdev, hdmi);
 
 	ret = mtk_hdmi_output_init(hdmi);
-- 
2.20.1


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Applied "ASoC: hdmi-codec: set plugged_cb to NULL when component removing" to the asoc tree

[Mark Brown]

The patch

   ASoC: hdmi-codec: set plugged_cb to NULL when component removing

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From 4aadf4b49ec7d80c5db842ca28479d07108c9484 Mon Sep 17 00:00:00 2001
From: Tzung-Bi Shih <tzungbi@google.com>
Date: Mon, 17 Feb 2020 11:16:52 +0800
Subject: [PATCH] ASoC: hdmi-codec: set plugged_cb to NULL when component
 removing

Sets plugged_cb to NULL when component removing to notify its consumers
: no further plugged status report is required.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200217105513.1.Icc323daaf71ad02f191fd8d91136b01b61eca5e3@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/codecs/hdmi-codec.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index 543363102d03..bc2903d27e6e 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -779,7 +779,17 @@ static int hdmi_of_xlate_dai_id(struct snd_soc_component *component,
 	return ret;
 }
 
+static void hdmi_remove(struct snd_soc_component *component)
+{
+	struct hdmi_codec_priv *hcp = snd_soc_component_get_drvdata(component);
+
+	if (hcp->hcd.ops->hook_plugged_cb)
+		hcp->hcd.ops->hook_plugged_cb(component->dev->parent,
+					      hcp->hcd.data, NULL, NULL);
+}
+
 static const struct snd_soc_component_driver hdmi_driver = {
+	.remove			= hdmi_remove,
 	.dapm_widgets		= hdmi_widgets,
 	.num_dapm_widgets	= ARRAY_SIZE(hdmi_widgets),
 	.of_xlate_dai_id	= hdmi_of_xlate_dai_id,
-- 
2.20.1


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