Re: [PATCH v3 17/19] [media] lirc: implement reading scancode

Re: [PATCH v3 17/19] [media] lirc: implement reading scancode

[Sean Young]

On Sat, Feb 25, 2017 at 11:51:32AM +0000, Sean Young wrote:
> @@ -362,10 +394,15 @@ static unsigned int ir_lirc_poll(struct file *filep,
>  
>  	poll_wait(filep, &lirc->wait_poll, wait);
>  
> -	if (!lirc->drv.attached)
> +	if (!lirc->drv.attached) {
>  		events = POLLHUP;
> -	else if (!kfifo_is_empty(&lirc->rawir))
> -		events = POLLIN | POLLRDNORM;
> +	} else if (lirc->rec_mode == LIRC_MODE_SCANCODE) {
> +		if (!kfifo_is_empty(&lirc->rawir))
> +			events = POLLIN | POLLRDNORM;
> +	} else if (lirc->rec_mode == LIRC_MODE_MODE2) {
> +		if (!kfifo_is_empty(&lirc->scancodes))
> +			events = POLLIN | POLLRDNORM;
> +	}
>  
>  	return events;
>  }

So one issue with with this API change is if you want to poll for both
raw IR and decoded scancodes. If poll were to return ready on raw IR and 
scancodes, existing code would not read the scancodes and end up in an
infinite loop.

So poll only returns ready for the current mode (either raw IR or scancodes).

If you want to read for both scancodes and raw IR, either:

1) Poll in scancode mode for 200ms, Poll in rawir for 200ms. Repeat.

2) Allow multiple fds to be opened on /dev/lircN device and open two
   file descriptors, one in each mode (I want to add this to rc-core anyway).

3) Add an ioctl in which you can set the "poll" mask, e.g.:

   unsigned mask = LIRC_MODE_MODE2 | LIRC_MODE_SCANCODE;
   ioctl(fd, LIRC_SET_POLL_MASK, &mask);
   

Sean

[PATCH] [media] lirc: introduce LIRC_SET_POLL_MODE

[Sean Young]

If you want to poll for both decoded scancodes and raw IR, then this
ioctl will help you.

int fd = open("/dev/lirc0", O_RDONLY | O_NONBLOCK);

for (;;) {
	unsigned mode = LIRC_MODE_SCANCODE | LIRC_MODE_MODE2;
	ioctl(fd, LIRC_SET_POLL_MODE, &mode);
	poll(&((struct pollfd){ .fd = fd, .events = POLLIN }), 1, -1);
	mode = LIRC_MODE_SCANCODE;
	ioctl(fd, LIRC_SET_REC_MODE, &mode);
	struct lirc_scancode sc;
	if (read(fd, &sc, sizeof(sc)) == sizeof(sc)) {
		printf("scancode protocol:%d scancode:%llx\n",
			sc.rc_type, sc.scancode);
	}
	mode = LIRC_MODE_MODE2;
	ioctl(fd, LIRC_SET_REC_MODE, &mode);
	unsigned sample;
	if (read(fd, &sample, sizeof(sample)) == sizeof(sample)) {
		if (LIRC_IS_SPACE(sample))
			printf("space %u\n", LIRC_VAL(sample)));
		if (LIRC_IS_PULSE(sample))
			printf("pulse %u\n", LIRC_VAL(sample)));
	}
}

Note that LIRC_SET_REC_MODE will also affect the poll mode, so you
must set it again before calling poll.

Signed-off-by: Sean Young <sean@mess.org>
---
 Documentation/media/uapi/rc/lirc-func.rst          |  1 +
 Documentation/media/uapi/rc/lirc-set-poll-mode.rst | 44 ++++++++++++++++++++++
 drivers/media/rc/ir-lirc-codec.c                   | 29 ++++++++++++--
 drivers/media/rc/rc-core-priv.h                    |  1 +
 include/uapi/linux/lirc.h                          |  9 +++++
 5 files changed, 80 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/media/uapi/rc/lirc-set-poll-mode.rst

diff --git a/Documentation/media/uapi/rc/lirc-func.rst b/Documentation/media/uapi/rc/lirc-func.rst
index 9b5a772..3ae92af 100644
--- a/Documentation/media/uapi/rc/lirc-func.rst
+++ b/Documentation/media/uapi/rc/lirc-func.rst
@@ -26,3 +26,4 @@ LIRC Function Reference
     lirc-set-rec-timeout-reports
     lirc-set-measure-carrier-mode
     lirc-set-wideband-receiver
+    lirc-set-poll-mode
diff --git a/Documentation/media/uapi/rc/lirc-set-poll-mode.rst b/Documentation/media/uapi/rc/lirc-set-poll-mode.rst
new file mode 100644
index 0000000..56112bb
--- /dev/null
+++ b/Documentation/media/uapi/rc/lirc-set-poll-mode.rst
@@ -0,0 +1,44 @@
+.. -*- coding: utf-8; mode: rst -*-
+
+.. _lirc_set_poll_mode:
+
+**********************************************
+ioctls LIRC_SET_POLL_MODE
+**********************************************
+
+Name
+====
+
+LIRC_SET_POLL_MODE - Set poll modes
+
+Synopsis
+========
+
+.. c:function:: int ioctl( int fd, LIRC_SET_POLL_MODE, __u32 modes)
+	:name: LIRC_SET_POLL_MODE
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by open().
+
+``modes``
+    Bitmask with enabled poll lirc modes
+
+Description
+===========
+
+Set lirc modes for which read readiness is reported by poll. Only
+:ref:`LIRC_MODE_MODE2 <lirc-mode-mode2>` and
+:ref:`LIRC_MODE_SCANCODE <lirc-mode-scancode>` are supported.
+Use :ref:`lirc_get_features` to find out which modes the driver supports.
+
+Note that using :ref:`lirc-set-rec-mode` resets the poll mode.
+
+Return Value
+============
+
+On success 0 is returned, on error -1 and the ``errno`` variable is set
+appropriately. The generic error codes are described at the
+:ref:`Generic Error Codes <gen-errors>` chapter.
diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
index 960703a..a2a2229 100644
--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -258,6 +258,24 @@ static long ir_lirc_ioctl(struct file *filep, unsigned int cmd,
 		}
 
 		lirc->rec_mode = val;
+		lirc->poll_mode = val;
+		return 0;
+
+	case LIRC_SET_POLL_MODE:
+		switch (dev->driver_type) {
+		case RC_DRIVER_SCANCODE:
+			if (val != LIRC_MODE_SCANCODE)
+				return -EINVAL;
+			break;
+		case RC_DRIVER_IR_RAW:
+			if (val & ~(LIRC_MODE_SCANCODE | LIRC_MODE_MODE2))
+				return -EINVAL;
+			break;
+		default:
+			return -ENOTTY;
+		}
+
+		lirc->poll_mode = val;
 		return 0;
 
 	case LIRC_GET_SEND_MODE:
@@ -396,11 +414,12 @@ static unsigned int ir_lirc_poll(struct file *filep,
 
 	if (!lirc->drv.attached) {
 		events = POLLHUP;
-	} else if (lirc->rec_mode == LIRC_MODE_SCANCODE) {
-		if (!kfifo_is_empty(&lirc->scancodes))
+	} else {
+		if ((lirc->poll_mode & LIRC_MODE_SCANCODE) &&
+		    !kfifo_is_empty(&lirc->scancodes))
 			events = POLLIN | POLLRDNORM;
-	} else if (lirc->rec_mode == LIRC_MODE_MODE2) {
-		if (!kfifo_is_empty(&lirc->rawir))
+		if ((lirc->poll_mode & LIRC_MODE_MODE2) &&
+		    !kfifo_is_empty(&lirc->rawir))
 			events = POLLIN | POLLRDNORM;
 	}
 
@@ -512,11 +531,13 @@ int ir_lirc_register(struct rc_dev *dev)
 
 	if (dev->driver_type == RC_DRIVER_SCANCODE) {
 		features |= LIRC_CAN_REC_SCANCODE;
+		node->poll_mode = LIRC_MODE_SCANCODE;
 		node->rec_mode = LIRC_MODE_SCANCODE;
 	} else if (dev->driver_type == RC_DRIVER_IR_RAW) {
 		features |= LIRC_CAN_REC_MODE2 | LIRC_CAN_REC_SCANCODE;
 		if (dev->rx_resolution)
 			features |= LIRC_CAN_GET_REC_RESOLUTION;
+		node->poll_mode = LIRC_MODE_MODE2;
 		node->rec_mode = LIRC_MODE_MODE2;
 	}
 	if (dev->tx_ir) {
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index b73222a..d630009 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -51,6 +51,7 @@ struct lirc_node {
 	u64 gap_duration;
 	bool gap;
 	bool send_timeout_reports;
+	int poll_mode;
 	int send_mode;
 	int rec_mode;
 };
diff --git a/include/uapi/linux/lirc.h b/include/uapi/linux/lirc.h
index d04fc62..70e8a71 100644
--- a/include/uapi/linux/lirc.h
+++ b/include/uapi/linux/lirc.h
@@ -134,6 +134,15 @@
 #define LIRC_SET_WIDEBAND_RECEIVER     _IOW('i', 0x00000023, __u32)
 
 /*
+ * For raw IR devices, both raw IR (LIRC_MODE_MODE2) and decodes scancodes
+ * (LIRC_MODE_SCANCODE) can be read. By default, poll will show read
+ * ready for the last mode set by LIRC_SET_REC_MODE. Use LIRC_SET_POLL_MODE
+ * LIRC_MODE_SCANCODE | LIRC_MODE_MODE2 to show read ready for both
+ * modes.
+ */
+#define LIRC_SET_POLL_MODE	       _IOW('i', 0x00000024, __u32)
+
+/*
  * struct lirc_scancode - decoded scancodes with protocol
  * @timestamp: Timestamp in nanoseconds using CLOCK_MONOTONIC when IR
  *	was decoded.
-- 
2.9.3