Re: [PATCH] Input: rmi4 - remove the need for artificial IRQ in case of HID

[Dmitry Torokhov]

Hi Benjamin,

On Mon, Apr 03, 2017 at 06:18:21PM +0200, Benjamin Tissoires wrote:
> The IRQ from rmi4 may interfere with the one we currently use on i2c-hid.
> Given that there is already a need for an external API from rmi4 to
> forward the attention data, we can, in this particular case rely on a
> separate workqueue to prevent cursor jumps.

Can you please walk me through how IRQ handler implemented by RMI driver
interferes with i2c-hid interrupt and why using a workqueue produces
better results.

Frankly, I do not like the whole attn_data business. OI wonder if we
we could have hidden it in HID transport code.

Thanks.

> 
> Reported-by: Cameron Gutman <aicommander@xxxxxxxxx>
> Reported-by: Thorsten Leemhuis <linux@xxxxxxxxxxxxx>
> Reported-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> Tested-by: Andrew Duggan <aduggan@xxxxxxxxxxxxx>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> ---
> 
> Hi Dmitry, Jiri,
> 
> This is a regression introduced by my code in v4.11.
> I do not think it is worth splitting between HID and input, there hasn't
> been any development in hid-rmi since v4.11-rc1.
> 
> Cheers,
> Benjamin
> 
>  drivers/hid/hid-rmi.c           |  64 ---------------------
>  drivers/input/rmi4/rmi_driver.c | 122 ++++++++++++++++++++++++----------------
>  include/linux/rmi.h             |   1 +
>  3 files changed, 75 insertions(+), 112 deletions(-)
> 
> diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
> index 5b40c26..4aa882c 100644
> --- a/drivers/hid/hid-rmi.c
> +++ b/drivers/hid/hid-rmi.c
> @@ -316,19 +316,12 @@ static int rmi_input_event(struct hid_device *hdev, u8 *data, int size)
>  {
>  	struct rmi_data *hdata = hid_get_drvdata(hdev);
>  	struct rmi_device *rmi_dev = hdata->xport.rmi_dev;
> -	unsigned long flags;
>  
>  	if (!(test_bit(RMI_STARTED, &hdata->flags)))
>  		return 0;
>  
> -	local_irq_save(flags);
> -
>  	rmi_set_attn_data(rmi_dev, data[1], &data[2], size - 2);
>  
> -	generic_handle_irq(hdata->rmi_irq);
> -
> -	local_irq_restore(flags);
> -
>  	return 1;
>  }
>  
> @@ -556,56 +549,6 @@ static const struct rmi_transport_ops hid_rmi_ops = {
>  	.reset		= rmi_hid_reset,
>  };
>  
> -static void rmi_irq_teardown(void *data)
> -{
> -	struct rmi_data *hdata = data;
> -	struct irq_domain *domain = hdata->domain;
> -
> -	if (!domain)
> -		return;
> -
> -	irq_dispose_mapping(irq_find_mapping(domain, 0));
> -
> -	irq_domain_remove(domain);
> -	hdata->domain = NULL;
> -	hdata->rmi_irq = 0;
> -}
> -
> -static int rmi_irq_map(struct irq_domain *h, unsigned int virq,
> -		       irq_hw_number_t hw_irq_num)
> -{
> -	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
> -
> -	return 0;
> -}
> -
> -static const struct irq_domain_ops rmi_irq_ops = {
> -	.map = rmi_irq_map,
> -};
> -
> -static int rmi_setup_irq_domain(struct hid_device *hdev)
> -{
> -	struct rmi_data *hdata = hid_get_drvdata(hdev);
> -	int ret;
> -
> -	hdata->domain = irq_domain_create_linear(hdev->dev.fwnode, 1,
> -						 &rmi_irq_ops, hdata);
> -	if (!hdata->domain)
> -		return -ENOMEM;
> -
> -	ret = devm_add_action_or_reset(&hdev->dev, &rmi_irq_teardown, hdata);
> -	if (ret)
> -		return ret;
> -
> -	hdata->rmi_irq = irq_create_mapping(hdata->domain, 0);
> -	if (hdata->rmi_irq <= 0) {
> -		hid_err(hdev, "Can't allocate an IRQ\n");
> -		return hdata->rmi_irq < 0 ? hdata->rmi_irq : -ENXIO;
> -	}
> -
> -	return 0;
> -}
> -
>  static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  {
>  	struct rmi_data *data = NULL;
> @@ -677,18 +620,11 @@ static int rmi_probe(struct hid_device *hdev, const struct hid_device_id *id)
>  
>  	mutex_init(&data->page_mutex);
>  
> -	ret = rmi_setup_irq_domain(hdev);
> -	if (ret) {
> -		hid_err(hdev, "failed to allocate IRQ domain\n");
> -		return ret;
> -	}
> -
>  	if (data->device_flags & RMI_DEVICE_HAS_PHYS_BUTTONS)
>  		rmi_hid_pdata.f30_data.disable = true;
>  
>  	data->xport.dev = hdev->dev.parent;
>  	data->xport.pdata = rmi_hid_pdata;
> -	data->xport.pdata.irq = data->rmi_irq;
>  	data->xport.proto_name = "hid";
>  	data->xport.ops = &hid_rmi_ops;
>  
> diff --git a/drivers/input/rmi4/rmi_driver.c b/drivers/input/rmi4/rmi_driver.c
> index d64fc92..5e65cba 100644
> --- a/drivers/input/rmi4/rmi_driver.c
> +++ b/drivers/input/rmi4/rmi_driver.c
> @@ -209,32 +209,46 @@ void rmi_set_attn_data(struct rmi_device *rmi_dev, unsigned long irq_status,
>  	attn_data.data = fifo_data;
>  
>  	kfifo_put(&drvdata->attn_fifo, attn_data);
> +
> +	schedule_work(&drvdata->attn_work);
>  }
>  EXPORT_SYMBOL_GPL(rmi_set_attn_data);
>  
> -static irqreturn_t rmi_irq_fn(int irq, void *dev_id)
> +static void attn_callback(struct work_struct *work)
>  {
> -	struct rmi_device *rmi_dev = dev_id;
> -	struct rmi_driver_data *drvdata = dev_get_drvdata(&rmi_dev->dev);
> +	struct rmi_driver_data *drvdata = container_of(work,
> +							struct rmi_driver_data,
> +							attn_work);
>  	struct rmi4_attn_data attn_data = {0};
>  	int ret, count;
>  
>  	count = kfifo_get(&drvdata->attn_fifo, &attn_data);
> -	if (count) {
> -		*(drvdata->irq_status) = attn_data.irq_status;
> -		drvdata->attn_data = attn_data;
> -	}
> +	if (!count)
> +		return;
>  
> -	ret = rmi_process_interrupt_requests(rmi_dev);
> +	*(drvdata->irq_status) = attn_data.irq_status;
> +	drvdata->attn_data = attn_data;
> +
> +	ret = rmi_process_interrupt_requests(drvdata->rmi_dev);
>  	if (ret)
> -		rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
> +		rmi_dbg(RMI_DEBUG_CORE, &drvdata->rmi_dev->dev,
>  			"Failed to process interrupt request: %d\n", ret);
>  
> -	if (count)
> -		kfree(attn_data.data);
> +	kfree(attn_data.data);
>  
>  	if (!kfifo_is_empty(&drvdata->attn_fifo))
> -		return rmi_irq_fn(irq, dev_id);
> +		schedule_work(&drvdata->attn_work);
> +}
> +
> +static irqreturn_t rmi_irq_fn(int irq, void *dev_id)
> +{
> +	struct rmi_device *rmi_dev = dev_id;
> +	int ret;
> +
> +	ret = rmi_process_interrupt_requests(rmi_dev);
> +	if (ret)
> +		rmi_dbg(RMI_DEBUG_CORE, &rmi_dev->dev,
> +			"Failed to process interrupt request: %d\n", ret);
>  
>  	return IRQ_HANDLED;
>  }
> @@ -242,7 +256,6 @@ static irqreturn_t rmi_irq_fn(int irq, void *dev_id)
>  static int rmi_irq_init(struct rmi_device *rmi_dev)
>  {
>  	struct rmi_device_platform_data *pdata = rmi_get_platform_data(rmi_dev);
> -	struct rmi_driver_data *data = dev_get_drvdata(&rmi_dev->dev);
>  	int irq_flags = irq_get_trigger_type(pdata->irq);
>  	int ret;
>  
> @@ -260,8 +273,6 @@ static int rmi_irq_init(struct rmi_device *rmi_dev)
>  		return ret;
>  	}
>  
> -	data->enabled = true;
> -
>  	return 0;
>  }
>  
> @@ -910,23 +921,27 @@ void rmi_enable_irq(struct rmi_device *rmi_dev, bool clear_wake)
>  	if (data->enabled)
>  		goto out;
>  
> -	enable_irq(irq);
> -	data->enabled = true;
> -	if (clear_wake && device_may_wakeup(rmi_dev->xport->dev)) {
> -		retval = disable_irq_wake(irq);
> -		if (retval)
> -			dev_warn(&rmi_dev->dev,
> -				 "Failed to disable irq for wake: %d\n",
> -				 retval);
> -	}
> +	if (irq) {
> +		enable_irq(irq);
> +		data->enabled = true;
> +		if (clear_wake && device_may_wakeup(rmi_dev->xport->dev)) {
> +			retval = disable_irq_wake(irq);
> +			if (retval)
> +				dev_warn(&rmi_dev->dev,
> +					 "Failed to disable irq for wake: %d\n",
> +					 retval);
> +		}
>  
> -	/*
> -	 * Call rmi_process_interrupt_requests() after enabling irq,
> -	 * otherwise we may lose interrupt on edge-triggered systems.
> -	 */
> -	irq_flags = irq_get_trigger_type(pdata->irq);
> -	if (irq_flags & IRQ_TYPE_EDGE_BOTH)
> -		rmi_process_interrupt_requests(rmi_dev);
> +		/*
> +		 * Call rmi_process_interrupt_requests() after enabling irq,
> +		 * otherwise we may lose interrupt on edge-triggered systems.
> +		 */
> +		irq_flags = irq_get_trigger_type(pdata->irq);
> +		if (irq_flags & IRQ_TYPE_EDGE_BOTH)
> +			rmi_process_interrupt_requests(rmi_dev);
> +	} else {
> +		data->enabled = true;
> +	}
>  
>  out:
>  	mutex_unlock(&data->enabled_mutex);
> @@ -946,20 +961,22 @@ void rmi_disable_irq(struct rmi_device *rmi_dev, bool enable_wake)
>  		goto out;
>  
>  	data->enabled = false;
> -	disable_irq(irq);
> -	if (enable_wake && device_may_wakeup(rmi_dev->xport->dev)) {
> -		retval = enable_irq_wake(irq);
> -		if (retval)
> -			dev_warn(&rmi_dev->dev,
> -				 "Failed to enable irq for wake: %d\n",
> -				 retval);
> -	}
> -
> -	/* make sure the fifo is clean */
> -	while (!kfifo_is_empty(&data->attn_fifo)) {
> -		count = kfifo_get(&data->attn_fifo, &attn_data);
> -		if (count)
> -			kfree(attn_data.data);
> +	if (irq) {
> +		disable_irq(irq);
> +		if (enable_wake && device_may_wakeup(rmi_dev->xport->dev)) {
> +			retval = enable_irq_wake(irq);
> +			if (retval)
> +				dev_warn(&rmi_dev->dev,
> +					 "Failed to enable irq for wake: %d\n",
> +					 retval);
> +		}
> +	} else {
> +		/* make sure the fifo is clean */
> +		while (!kfifo_is_empty(&data->attn_fifo)) {
> +			count = kfifo_get(&data->attn_fifo, &attn_data);
> +			if (count)
> +				kfree(attn_data.data);
> +		}
>  	}
>  
>  out:
> @@ -998,9 +1015,12 @@ EXPORT_SYMBOL_GPL(rmi_driver_resume);
>  static int rmi_driver_remove(struct device *dev)
>  {
>  	struct rmi_device *rmi_dev = to_rmi_device(dev);
> +	struct rmi_driver_data *data = dev_get_drvdata(&rmi_dev->dev);
>  
>  	rmi_disable_irq(rmi_dev, false);
>  
> +	cancel_work_sync(&data->attn_work);
> +
>  	rmi_f34_remove_sysfs(rmi_dev);
>  	rmi_free_function_list(rmi_dev);
>  
> @@ -1230,9 +1250,15 @@ static int rmi_driver_probe(struct device *dev)
>  		}
>  	}
>  
> -	retval = rmi_irq_init(rmi_dev);
> -	if (retval < 0)
> -		goto err_destroy_functions;
> +	if (pdata->irq) {
> +		retval = rmi_irq_init(rmi_dev);
> +		if (retval < 0)
> +			goto err_destroy_functions;
> +	}
> +
> +	data->enabled = true;
> +
> +	INIT_WORK(&data->attn_work, attn_callback);
>  
>  	if (data->f01_container->dev.driver)
>  		/* Driver already bound, so enable ATTN now. */
> diff --git a/include/linux/rmi.h b/include/linux/rmi.h
> index 64125443..dc90178 100644
> --- a/include/linux/rmi.h
> +++ b/include/linux/rmi.h
> @@ -364,6 +364,7 @@ struct rmi_driver_data {
>  
>  	struct rmi4_attn_data attn_data;
>  	DECLARE_KFIFO(attn_fifo, struct rmi4_attn_data, 16);
> +	struct work_struct attn_work;
>  };
>  
>  int rmi_register_transport_device(struct rmi_transport_dev *xport);
> -- 
> 2.9.3
> 

-- 
Dmitry