On 12/07/2015 02:53 PM, Alexander Aring wrote:
Hi,
On Mon, Dec 07, 2015 at 01:47:06PM +0100, Michael Hennerich wrote:
...
+static struct ieee802154_ops adf7242_ops = {
+ .owner = THIS_MODULE,
+ .xmit_sync = adf7242_xmit,
+ .ed = adf7242_ed,
+ .set_channel = adf7242_channel,
+ .set_hw_addr_filt = adf7242_set_hw_addr_filt,
+ .start = adf7242_start,
+ .stop = adf7242_stop,
+ .set_csma_params = adf7242_set_csma_params,
+ .set_frame_retries = adf7242_set_frame_retries,
+ .set_txpower = adf7242_set_txpower,
+ .set_promiscuous_mode = adf7242_set_promiscuous_mode,
+ .set_cca_ed_level = adf7242_set_cca_ed_level,
Nice to see so many callbacks implemented. The only things I see missing
is xmit_async, set_lbt and set_cca_mode. I would not make it a
requirements to get these hooked up before merging this patch but we
should consider it as todo items.
The part only supports CCA mode Energy above threshold.
Not sure what this LBT mode does on the AT86RFxxx driver.
This is for sub 1Ghz regulations in some country (Japan/Europe) area,
there CSMA/CA accoridng 802.15.4 isn't allowed at sub 1-Ghz, that's why
they introduced LBT.
That reminds me to work on a regulator db, again. :-)
Nevertheless it should not related to 2.4 Ghz global ISM band, so far I
know.
The ADF7242 only supports CSMA-CA and not some other listen before talk
flavour. The only oher option is to turn CSMA-CA completly off.
Another thing for ToDo list, add support for turning CSMA-CA handling
complete off, many transceiver has such option.
There exists ways currently to turn off CSMA handling only by choosing
the right backoff exponents, 802.15.4 writes:
Note that if macMinBE is set to zero, collision avoidance will be
disabled during the first iteration of this algorithm.
First iteration only? And I think that is for slotted operation.
I wouldn't overload MinBe with an option to disable CSMA-CA.
Maybe add a new command?
Okay then another ToDo for wpan-tools would be to make a nice printout
that CSMA is disabled if "macMinBE is set to zero".
I'm also not sure if we need to supprot the async mode, while the sync mode
is working. For me the async mode looks like it tries to workaround some HW
access issues.
We came to the conclusion that "sync" callback is a workaround that
people can use spi_sync. :-)
Hmmm - I don't quite understand.
The difference is that xmit_sync blocks until the packet is transmitted,
while async returns immediately.
spi_sync can be only used from context that can sleep. While spi_async
runs it's own queue and provides a completion callback.
These radios can only do one thing at the time. And in both cases there
are queues that are being stopped while the radio driver is busy doing
something.
So the only thing is the IF down/up issue?
The ADF7242 would actually return an error if the packet wasn’t sent
or ACKed by the receiver. It's still looks like this information
isn’t being used anywhere.
Not a big deal - but in addition received ACKs (that would potentially
indicate that the packet was successfully delivered) cause warnings and
are completely dropped as well.
Ununfortunately the nfc subsystem works also which such sync callback.
Currently working of sync xmit:
- ieee802154_tx (softirq context, might_sleep() will fail).
- set parameters schedule workqueue /* queue_work(...) */
/* sleeping phase */ <-- we lost the context of ieee802154_tx, the
locks are not held anymore. Others
netdev_ops are possible.
- ieee802154_xmit_worker will be scheduled <--- Does this still
working if a stop
callback was running
inside the
"sleeping phase"?
- /* sleeping: wait for completion */ when tx complete is triggered
irq triggered.
With async:
The context of ieee802154_tx will be held until the driver "xmit_async"
callback is done. This callback should call spi_async which cannot be
interrupted until the "last" complete callback is done.
Then a stop callback can occur at the time where the hardware "actually"
transmit the frame. This is a complete async process, there is no "wait
for completion" anymore. The complete replacement would be
"ieee802154_xmit_complete".
Drivers should also disable/enable the tx/rx irq's when doing stop/start,
if possible.
- Alex
--
Greetings,
Michael
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