BCM5722 Programmer’s Guide
10/15/07
Broadcom Corporation
Page 55 Status Block Document 5722-PG101-R
The Status Block format for these devices is given below.
• The Status Tag field contains an unique eight-bit tag value in bits 7:0 when the Status Tagged Status Mode bit of the
Miscellaneous Host Control register (see “Miscellaneous Host Control Register (Offset 0x68)” on page 204) is set to 1.
This Status Tag can be returned to the Mailbox 0 register at location 31:24 (see “Interrupt Mailbox 0 Register (Offset
0x200–0x207)” on page 238) by host driver. When the remaining Mailbox 0 register bits 23:0 are written as 0, the tag
field of the Mailbox 0 register is compared with the tag field of the last status block to be DMAed to host. If the tag
returned is not equivalent to the tag of the last status block DMAed to the host, the interrupt state is entered.
• The Receive Producer Ring Consumer Index field contains the controller’s current Consumer Index value for the
Receive Producer Ring. This field indicates how many receive descriptors are in the receive producer ring that the
controller has consumed. For more information regarding this ring, see “Receive Producer Ring” on page 49.
• The Receive Mini Ring Consumer Index field contains the controller’s current Consumer Index value for the Receive
Producer Mini Ring. This field indicates how many receive descriptors are in the mini ring that the controller has
consumed. For more information regarding this ring, see “Receive Producer Ring” on page 49.
• The Receive Return Rings 1–4 Producer Indices fields contain controller’s current Producer Index value for the each of
the Receive Return Rings. When the controller receives a packet and writes that packet data into host memory via
DMA, it will increment the Producer Index for the corresponding Receive Return ring. When a Producer Index is
incremented, it is a signal to software that a newly arrived receive packet is ready to be processed.
• The Send Ring Consumer Index field contains controller’s current Consumer Index value for the Send Ring. When the
controller completes the read DMA of the host buffer associated with a send BD, the controller will update the Send
Ring Consumer Index. This provides the host software with an indication that the controller has buffered this send data
and, therefore, the host software may free the buffer that was just consumed by the device.
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