Unverified Commit f07980d4 authored by Tzung-Bi Shih's avatar Tzung-Bi Shih Committed by Mark Brown
Browse files

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: 5d3c6447 ("drm/mediatek: support HDMI jack status reporting")
Signed-off-by: default avatarTzung-Bi Shih <tzungbi@google.com>
Acked-by: default avatarCK Hu <ck.hu@mediatek.com>
Link: https://lore.kernel.org/r/20200217105513.2.I477092c2f104fd589133436c3ae4590e6fc6323b@changeid


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 2f0b4203

drivers/gpu/drm/mediatek/mtk_hdmi.c

+10 −1
Original line number Diff line number Diff line
@@ -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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