On Thu, Oct 27, 2016 at 04:44:01PM +0900, Andi Shyti wrote:

Hi Sean,

it's been a while :)

I was going through your review fixing what needs to be fixed,
but...

quoted

quoted

@@ -153,7 +153,7 @@ static ssize_t ir_lirc_transmit_ir(struct file *file, const char __user *buf,
 	}
 
 	ret = dev->tx_ir(dev, txbuf, count);
-	if (ret < 0)
+	if (ret < 0 || dev->driver_type == RC_DRIVER_IR_RAW_TX)

Just because a driver only does transmit doesn't mean its transmit ABI
should change.

Now this bit of code is pretty horrible. It ensures that the call to write()
takes at least as long as the length of the transmit IR by sleeping. That's
not much of a guarantee that the IR has been sent.

Note that in the case of ir-spi, since your spi transfer is sync no sleep
should be introduced here.

The gap calculation in lirc checks that if the call to write() took _longer_
than expected wait before sending the next IR code (when either multiple
IR codes or repeats are specified). Introducing the sleep in the kernel
here does not help at all, lirc already ensures that it waits as long as
the IR is long (see schedule_repeat_timer in lirc).

This change was introduced in 3.10, commit f8e00d5. 

... I'm not sure what can be done here. I get your point and I
understand that this indeed is a kind of fake sync point and by
doing this I 

My original plan was to send a patch which just removes the silly wait,
but on further investigating debian stable and testing still carry a
lirc version that depend on it, so that's not going to fly.

How about creating two different functions:

- ir_lirc_transmit_ir where we actually do what the function
  already does
- ir_lirc_transmit_no_sync where the function we don't wait
  because the the sync is done on a different level (for example
  in the SPI case).

SPI does approximately the same thing.

Since we have to be able to switch between waiting and not waiting, 
we need some sort of ABI for this. I think this warrants a new ioctl;
I'm not sure how else it can be done. I'll be sending out a patch
shortly.


Sean