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

[Chanwoo Choi]

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().

> +	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>

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics