Hi, it's me again.
So I'm trying to use the Linux input system to report key events from
the device.
This is my code so far: http://sprunge.us/KfhF
As you can see, I'm trying to send event 1 whenever the watchdog work is
executed.
I can see from dmesg that the task is actually being executed, but when
I run evtest
to check if I actually receive the messages, I see nothing.
Any help would be much appreciated.
Thanks,
Jose
On 06/11/14 20:56, Jose Diez wrote:
Ah, I was hoping there would be a way to avoid having to patch the
kernel itself.
Thanks again,
Jose
On 06/11/14 20:22, Benjamin Tissoires wrote:
On Thu, Nov 6, 2014 at 3:18 PM, Jose Diez<jose@xxxxxxxxxxx> wrote:
Okay, so I've solved the watchdog issue, and now I want the driver
to be
loaded automatically. I've copied the module to
/lib/modules/<kernel>/ and
run depmod -a, and I can see it in modules.alias, but it looks like
hid_generic grabs it first upon boot - my module is loaded
correctly, but it
doesn't grab the HID device.
If I `modprobe -r hid_generic` and then load my module, everything
works
correctly.
Yep. You need to add your device VendorID/ProductID in
hid_have_special_driver[] in hid-core.c.
This will tell hid-generic not to grab your device, and your custom
module will take over.
Cheers,
Benjamin
On 06/11/14 19:28, Jose Diez wrote:
Thanks Benjamin. That fixed the issue. Have a great day.
On 06/11/14 18:57, Benjamin Tissoires wrote:
Hi Jose,
On Thu, Nov 6, 2014 at 1:33 PM, Jose Diez<jose@xxxxxxxxxxx> wrote:
Hello linux-input,
I'm trying to write a custom HID driver. It works fine, and I can
send
reports just fine, but one of the requirements of this device is
that I
have
to reply to reports with code 62 with another report with code
62, which
resets a watchdog in the device.
This is my code so far:http://codepad.org/m4QiWhDt
The problem is in line 40. It seems like I'm not allowed to call
hid_hw_output_report from the raw_event callback handler. I've tried
surrounding the call with spin_locks, but I still get the
"scheduling
while
atomic" error.
Yeah, when you are in the .event callback, you are basically
called by
an IRQ, so you can not schedule a potentially blocking operation.
I'm not sure how to approach this - can someone help? It would be
much
appreciated. Thanks.
I would use a worker to do what you are trying to do. You can have a
look at the reset_worker we have in drivers/hid/hid-rmi.c.
When the event is not one we expected, we schedule a worker thread
which then sends an output report to the device. This way, the
blocking operation is sent from a different thread than the IRQ one.
It is kind of what you are willing to do.
There are many other examples of workers in the hid subtree, or you
can refer to the doc to find out more.
Cheers,
Benjamin
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