On my OMAP-L137 target @ 192 MHz:
DSP core (CCS 3.3.82.13; DSPBIOS 5.41.03.17) performs data collection/digital processing
ARM core (Linux 2.6) transfers data through TCP/IP
On DSP core data are received from sampling logic at sampling rate through synchronous DMA serial transfers,
triggering HW IRQ, whose calbacks perform input data checking/processing.
Sampling rates are 128,256, up to 8192 Hz.
Whichever the sampling rate, DSP core assembles data in 64Hz packets,
then sends the packet to ARM core through DspLink CHNL issue/reclaim method.
ARM core in turn polls data packet availability through issue/reclaim method
at substantial rate >> 64 Hz: this of course results in "timeout" errors, until
a packet is actually retrieved.
At lower sampling rates all is ok.
When sampling rate rises, a single overrun appears in serial IRQ, exactly at 64 Hz,
i.e. when the issue/reclaim call is executed on DSP core.
So I need to clearify the following questions:
DSP/BIOS™ LINK - Version 1.61
14.6 CHNL
14.6.1 Typical sequence
1. Issue allocated buffer(s) to the channel(s) created earlier. Usually:
A primed buffer is issued on an output channel to be received by the
remote client on the DSP.
An empty buffer is issued on an input channel to receive the data issued
by remote client on the DSP.
2. Reclaim a buffer on the channel to which a buffer was issued in the
previous step. This is a synchronous operation i.e. the execution of the
client is blocked until the IO operation is successful (or a timeout occurs).
Please note that API reference reports:
EXPORT_API DSP_STATUS CHNL_reclaim ( IN ProcessorId procId, IN ChannelId chnlId, IN Uint32 timeout, IN OUT ChannelIOInfo * ioReq )
timeout Timeout value for this operation. Unit of timeout is OS dependent.
1) The DSP client block affects HW irqs handling ?
2) Which is (roughy) the time required by ARM to reclaim up to 16K words ?
3) Which is the unit of timeout ?
Any other suggestion is appreciated.
Thank you for your attention.
