[PATCH] drm/mediatek: mtk_hdmi_common: take i2c adapter module reference

[PATCH] drm/mediatek: mtk_hdmi_common: take i2c adapter module reference

[Johan Hovold]

The i2c subsystem currently blocks during adapter deregistration
whenever there are consumers holding a reference.

Switch to using of_get_i2c_adapter_by_node() which also takes a
reference to the adapter module so that an attempt to unload the module
while in use fails gracefully instead of blocking uninterruptibly.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/gpu/drm/mediatek/mtk_hdmi_common.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
index a049489daa2d..042b98e5a519 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
@@ -290,6 +290,13 @@ static int mtk_hdmi_get_cec_dev(struct mtk_hdmi *hdmi, struct device *dev, struc
 	return 0;
 }
 
+static void mtk_hdmi_put_adapter(void *_adap)
+{
+	struct i2c_adapter *adap = _adap;
+
+	i2c_put_adapter(adap);
+}
+
 static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device *pdev,
 				   const char * const *clk_names, size_t num_clocks)
 {
@@ -328,12 +335,12 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device
 	if (!i2c_np)
 		return dev_err_probe(dev, -EINVAL, "No ddc-i2c-bus in connector\n");
 
-	hdmi->ddc_adpt = of_find_i2c_adapter_by_node(i2c_np);
+	hdmi->ddc_adpt = of_get_i2c_adapter_by_node(i2c_np);
 	of_node_put(i2c_np);
 	if (!hdmi->ddc_adpt)
 		return dev_err_probe(dev, -EPROBE_DEFER, "Failed to get ddc i2c adapter by node\n");
 
-	ret = devm_add_action_or_reset(dev, mtk_hdmi_put_device, &hdmi->ddc_adpt->dev);
+	ret = devm_add_action_or_reset(dev, mtk_hdmi_put_adapter, hdmi->ddc_adpt);
 	if (ret)
 		return ret;
 
-- 
2.54.0

Re: [PATCH] drm/mediatek: mtk_hdmi_common: take i2c adapter module reference

[CK Hu (胡俊光)]

On Thu, 2026-07-16 at 15:21 +0200, Johan Hovold wrote:
> The i2c subsystem currently blocks during adapter deregistration
> whenever there are consumers holding a reference.
> 
> Switch to using of_get_i2c_adapter_by_node() which also takes a
> reference to the adapter module so that an attempt to unload the module
> while in use fails gracefully instead of blocking uninterruptibly.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/gpu/drm/mediatek/mtk_hdmi_common.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
> index a049489daa2d..042b98e5a519 100644
> --- a/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi_common.c
> @@ -290,6 +290,13 @@ static int mtk_hdmi_get_cec_dev(struct mtk_hdmi *hdmi, struct device *dev, struc
>  	return 0;
>  }
>  
> +static void mtk_hdmi_put_adapter(void *_adap)
> +{
> +	struct i2c_adapter *adap = _adap;
> +
> +	i2c_put_adapter(adap);
> +}
> +
>  static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device *pdev,
>  				   const char * const *clk_names, size_t num_clocks)
>  {
> @@ -328,12 +335,12 @@ static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi, struct platform_device
>  	if (!i2c_np)
>  		return dev_err_probe(dev, -EINVAL, "No ddc-i2c-bus in connector\n");
>  
> -	hdmi->ddc_adpt = of_find_i2c_adapter_by_node(i2c_np);
> +	hdmi->ddc_adpt = of_get_i2c_adapter_by_node(i2c_np);
>  	of_node_put(i2c_np);
>  	if (!hdmi->ddc_adpt)
>  		return dev_err_probe(dev, -EPROBE_DEFER, "Failed to get ddc i2c adapter by node\n");
>  
> -	ret = devm_add_action_or_reset(dev, mtk_hdmi_put_device, &hdmi->ddc_adpt->dev);
> +	ret = devm_add_action_or_reset(dev, mtk_hdmi_put_adapter, hdmi->ddc_adpt);
>  	if (ret)
>  		return ret;
>  

Re: [PATCH] drm/mediatek: mtk_hdmi_common: take i2c adapter module reference

[Chun-Kuang Hu]

Johan Hovold <johan@kernel.org> 於 2026年7月16日週四 下午1:21寫道：
>
> The i2c subsystem currently blocks during adapter deregistration
> whenever there are consumers holding a reference.
>
> Switch to using of_get_i2c_adapter_by_node() which also takes a
> reference to the adapter module so that an attempt to unload the module
> while in use fails gracefully instead of blocking uninterruptibly.

Applied to mediatek-drm-fixes [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes

Regards,
Chun-Kuang.

>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---