On 2013-03-20 15:50, H Hartley Sweeten wrote:
On Wednesday, March 20, 2013 4:46 AM, Ian Abbott wrote:
On 2013-03-20 01:07, H Hartley Sweeten wrote:
Each comedi_subdevice uses one of the minors allocated to the
comedi subsystem. The devices used with this driver need a minimum
of 2 and a maximum of 5 subdevices.
Only allocate and initialize the number of subdevices actually needed
by the device.
This will break user-space code using one of these devices that assume
the previous subdevice numbers are still valid.
Fair enough. I'll drop this piece.
But, it seems like a waste to allocate the space for the unused subdevices and
waste the minors. I'm not sure how much space each struct comedi_subevice
takes but they probably add up.
It would be possible to add a layer of indirection to effectively pack
the unused subdevices, although that would increase the overhead for
used subdevices and complicate the code. Probably not worth it.
The subdevice minors are allocated dynamically to those subdevices that
support asynchronous commands, so unused subdevices won't waste the minors.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=-
-=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=-
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