Re: [RFC] What are the goals for the architecture of an in-kernel IR system?

Mauro Carvalho Chehab
2010-03-31T06:02:58Z

David Härdeman wrote:
> On Sun, Mar 28, 2010 at 09:51:17PM -0300, Mauro Carvalho Chehab wrote:
>> I spoke too soon... removing the index causes a problem at the read ioctl: there's no way
>> to retrieve just the non-sparsed values.
>>
>> There's one solution that would allow both read/write and compat to work nicely,
>> but the API would become somewhat asymmetrical:
>>
>> At get (EVIOCGKEYCODEBIG):
>> use index/len as input and keycode/scancode as output;
>>
>> At set (EVIOCSKEYCODEBIG):
>> use scancode/keycode/len as input (and, optionally, index as output).
>>
>
> This was exactly the approach I had in mind when I suggested using
> indexes.

Doesn't work perfectly. The asymmetry has a side effect on the internal logic:

EVIOCGKEYCODEBIG should be implemented with a pseudo-code like:
kt_entry = getkeycodebig_from_index(index);

EVIOCSKEYCODEBIG should be implemented with a pseudo-code like:
kt_entry = getkeycodebig_from_scan(scan, len);
old_key = kt_entry->keycode;

kt_entry->keycode = newkey;
if (setkeycodebig(kt_entry) == 0)
keyup(old_key);

As you see, the input parameters for the getkeycodebig*() are different.

So, this approach requires 3 ops instead of 2. Yet, as scancode->keycode is
needed anyway, this doesn't actually hurts.

I just added the patches that implement those two ioctls on my IR development tree.
I tested only the original EVIOCGKEYCODE/EVIOSGKEYCODE and calling a clear_table
function using EVIOCSKEYCODEBIG via emulation.

My next step is to test the remaining ir-keytable functions via emulation, and then
implement the *BIG ioctls at ir-core, for testing.

I haven't test yet the *keycode*default methods.

After having it fully tested, I'll submit the complete input ioctl patch via ML.

--

Cheers,
Mauro