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Altera_Forum
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12 years ago

deadlock of chained dma based design on rmmod of Linux driver

I encountered the deadlock problem of chained dma based design when doing rmmod of Linux driver module. SignalTap shows that tx_sel_pcnt and tx_sel_slave signals (i.e. for altpcierd_rc_slave mo...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

It turned out to be a driver issue.

Apparently, pci_disable_device() also disables bus mastering bit in pci config, which is enabled by default in Altera chaining DMA example.

However, pci_enable_device() does not turned on bus mastering config bit, pci_set_master() should be called in the probe function, otherwise DMAs would not work.