A negative (or very large) channel number causes a segmentation fault in edma_free_channel.
void edma_free_channel(unsigned channel)
{
unsigned ctlr;
ctlr = EDMA_CTLR(channel);
channel = EDMA_CHAN_SLOT(channel);
if (channel >= edma_info[ctlr]->num_channels)
return;
If channel is negative or large then ctlr is also large causing a segmentation fault in the channel validation conditional statement.
This can happen if allocating a channel returns a negative number that indicates allocation failure which is mistakenly passed to the free routine during cleanup.
Whilst this is an error condition it should be flagged as such.
