control. Controller does not automatically generate pause frames
based on number of available RX buffers so it's very hard to
know when driver should generate XON frame in time. The only
mechanism driver can detect low number of RX buffer condition is
ET_INTR_RXRING0_LOW or ET_INTR_RXRING1_LOW interrupt. This
interrupt is generated whenever controller notices the number of
available RX buffers are lower than pre-programmed value(
ET_RX_RING0_MINCNT and ET_RX_RING1_MINCNT register). This scheme
does not provide a way to detect when controller sees enough number
of RX buffers again such that efficient generation of XON/XOFF
frame is not easy.
While here, add more flow control related register definition.
interrupt is ours. Note, interrupts are automatically ACKed when
the status register is read.
Add RX/TX DMA error to interrupt handler and do full controller
reset if driver happen to encounter these errors. There is no way
to recover from these DMA errors without controller reset.
Rename local variable name intrs with status to enhance
readability.
While I'm here, rename ET_INTR_TXEOF and ET_INTR_RXEOF to
ET_INTR_TXDMA and ET_INTR_RXDMA respectively. These interrupts
indicate that a frame is successfully DMAed to controller's
internal FIFO and they have nothing to do with EOF(end of frame).
Driver does not need to wait actual end of TX/RX of a frame(e.g.
no need to wait the end signal of TX which is generated when a
frame in TX FIFO is emptied by MAC). Previous names were somewhat
confusing.
suspend state. This will save more power.
On resume, make sure to enable all clocks. While I'm here, if
controller is not fast ethernet, enable gigabit PHY.
