Re: [PATCH v5 6/6] drm/bridge/sii8620: use micro-USB cable detection logic to detect MHL

[Chanwoo Choi]

Hi,

On 2018ë 02ì 27ì 21:05, Andrzej Hajda wrote:
> On 27.02.2018 12:08, Chanwoo Choi wrote:
>> Hi,
>>
>> On 2018ë 02ì 27ì 16:11, Andrzej Hajda wrote:
>>> From: Maciej Purski <m.purski@xxxxxxxxxxx>
>>>
>>> Currently MHL chip must be turned on permanently to detect MHL cable. It
>>> duplicates micro-USB controller's (MUIC) functionality and consumes
>>> unnecessary power. Lets use extcon attached to MUIC to enable MHL chip
>>> only if it detects MHL cable.
>>>
>>> Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx>
>>> Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
>>> ---
>>> v5: updated extcon API
>>>
>>> This is rework of the patch by Maciej with following changes:
>>> - use micro-USB port bindings to get extcon, instead of extcon property,
>>> - fixed remove sequence,
>>> - fixed extcon get state logic.
>>>
>>> Code finding extcon node is hacky IMO, I guess ultimately it should be done
>>> via some framework (maybe even extcon), or at least via helper, I hope it
>>> can stay as is until the proper solution will be merged.
>>>
>>> Signed-off-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
>>> ---
>>>  drivers/gpu/drm/bridge/sil-sii8620.c | 97 ++++++++++++++++++++++++++++++++++--
>>>  1 file changed, 94 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/sil-sii8620.c b/drivers/gpu/drm/bridge/sil-sii8620.c
>>> index 9e785b8e0ea2..62b0adabcac2 100644
>>> --- a/drivers/gpu/drm/bridge/sil-sii8620.c
>>> +++ b/drivers/gpu/drm/bridge/sil-sii8620.c
>>> @@ -17,6 +17,7 @@
>>>  
>>>  #include <linux/clk.h>
>>>  #include <linux/delay.h>
>>> +#include <linux/extcon.h>
>>>  #include <linux/gpio/consumer.h>
>>>  #include <linux/i2c.h>
>>>  #include <linux/interrupt.h>
>>> @@ -25,6 +26,7 @@
>>>  #include <linux/list.h>
>>>  #include <linux/module.h>
>>>  #include <linux/mutex.h>
>>> +#include <linux/of_graph.h>
>>>  #include <linux/regulator/consumer.h>
>>>  #include <linux/slab.h>
>>>  
>>> @@ -81,6 +83,10 @@ struct sii8620 {
>>>  	struct edid *edid;
>>>  	unsigned int gen2_write_burst:1;
>>>  	enum sii8620_mt_state mt_state;
>>> +	struct extcon_dev *extcon;
>>> +	struct notifier_block extcon_nb;
>>> +	struct work_struct extcon_wq;
>>> +	int cable_state;
>>>  	struct list_head mt_queue;
>>>  	struct {
>>>  		int r_size;
>>> @@ -2175,6 +2181,77 @@ static void sii8620_init_rcp_input_dev(struct sii8620 *ctx)
>>>  	ctx->rc_dev = rc_dev;
>>>  }
>>>  
>>> +static void sii8620_cable_out(struct sii8620 *ctx)
>>> +{
>>> +	disable_irq(to_i2c_client(ctx->dev)->irq);
>>> +	sii8620_hw_off(ctx);
>>> +}
>>> +
>>> +static void sii8620_extcon_work(struct work_struct *work)
>>> +{
>>> +	struct sii8620 *ctx =
>>> +		container_of(work, struct sii8620, extcon_wq);
>>> +	int state = extcon_get_state(ctx->extcon, EXTCON_DISP_MHL);
>>> +
>>> +	if (state == ctx->cable_state)
>>> +		return;
>>> +
>>> +	ctx->cable_state = state;
>>> +
>>> +	if (state > 0)
>>> +		sii8620_cable_in(ctx);
>>> +	else
>>> +		sii8620_cable_out(ctx);
>>> +}
>>> +
>>> +static int sii8620_extcon_notifier(struct notifier_block *self,
>>> +			unsigned long event, void *ptr)
>>> +{
>>> +	struct sii8620 *ctx =
>>> +		container_of(self, struct sii8620, extcon_nb);
>>> +
>>> +	schedule_work(&ctx->extcon_wq);
>>> +
>>> +	return NOTIFY_DONE;
>>> +}
>>> +
>>> +static int sii8620_extcon_init(struct sii8620 *ctx)
>>> +{
>>> +	struct extcon_dev *edev;
>>> +	struct device_node *musb, *muic;
>>> +	int ret;
>>> +
>>> +	/* get micro-USB connector node */
>>> +	musb = of_graph_get_remote_node(ctx->dev->of_node, 1, -1);
>>> +	/* next get micro-USB Interface Controller node */
>>> +	muic = of_get_next_parent(musb);
>>> +
>>> +	if (!muic) {
>>> +		dev_info(ctx->dev, "no extcon found, switching to 'always on' mode\n");
>>> +		return 0;
>>> +	}
>>> +
>>> +	edev = extcon_find_edev_by_node(muic);
>>> +	of_node_put(muic);
>>> +	if (IS_ERR(edev)) {
>>> +		if (PTR_ERR(edev) == -EPROBE_DEFER)
>>> +			return -EPROBE_DEFER;
>>> +		dev_err(ctx->dev, "Invalid or missing extcon\n");
>>> +		return PTR_ERR(edev);
>>> +	}
>>> +
>>> +	ctx->extcon = edev;
>>> +	ctx->extcon_nb.notifier_call = sii8620_extcon_notifier;
>>> +	INIT_WORK(&ctx->extcon_wq, sii8620_extcon_work);
>>> +	ret = extcon_register_notifier(edev, EXTCON_DISP_MHL, &ctx->extcon_nb);
>> You better to use devm_extcon_register_notifier().
> 
> With devm version I risk that in case of device unbind notification will
> be called after .remove callback, it seems to me quite dangerous. Or am
> I missing something?

If you use the cancel_work_sync() in remove() instead of flush_work(),
you can use the 'devm_extcon_*'.

> 
> Regards
> Andrzej
> 
>>
>>> +	if (ret) {
>>> +		dev_err(ctx->dev, "failed to register notifier for MHL\n");
>>> +		return ret;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>>  static inline struct sii8620 *bridge_to_sii8620(struct drm_bridge *bridge)
>>>  {
>>>  	return container_of(bridge, struct sii8620, bridge);
>>> @@ -2307,13 +2384,20 @@ static int sii8620_probe(struct i2c_client *client,
>>>  	if (ret)
>>>  		return ret;
>>>  
>>> +	ret = sii8620_extcon_init(ctx);
>>> +	if (ret < 0) {
>>> +		dev_err(ctx->dev, "failed to initialize EXTCON\n");
>>> +		return ret;
>>> +	}
>>> +
>>>  	i2c_set_clientdata(client, ctx);
>>>  
>>>  	ctx->bridge.funcs = &sii8620_bridge_funcs;
>>>  	ctx->bridge.of_node = dev->of_node;
>>>  	drm_bridge_add(&ctx->bridge);
>>>  
>>> -	sii8620_cable_in(ctx);
>>> +	if (!ctx->extcon)
>>> +		sii8620_cable_in(ctx);
>>>  
>>>  	return 0;
>>>  }
>>> @@ -2322,8 +2406,15 @@ static int sii8620_remove(struct i2c_client *client)
>>>  {
>>>  	struct sii8620 *ctx = i2c_get_clientdata(client);
>>>  
>>> -	disable_irq(to_i2c_client(ctx->dev)->irq);
>>> -	sii8620_hw_off(ctx);
>>> +	if (ctx->extcon) {
>>> +		extcon_unregister_notifier(ctx->extcon, EXTCON_DISP_MHL,
>>> +					   &ctx->extcon_nb);
>> Don't need to unregister the notifier if using devm_extcon_register_notifier().
>>
>>> +		flush_work(&ctx->extcon_wq);
>>> +		if (ctx->cable_state > 0)
>>> +			sii8620_cable_out(ctx);
>>> +	} else {
>>> +		sii8620_cable_out(ctx);
>>> +	}
>>>  	drm_bridge_remove(&ctx->bridge);
>>>  
>>>  	return 0;
>>>
>> If you use the resource managed function (devm_extcon_register_notifier), Looks good to me.
>> Reviewed-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
>>
> 
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> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics