[#4313] System with EMAC driver enabled - Core not idling

Submitted By: Michael Hennerich

Open Date

2008-08-06 04:29:44 Close Date

2008-08-06 04:59:12

Priority:

Medium Assignee:

Michael Hennerich

Status:

Closed Fixed In Release:

N/A

Found In Release:

N/A Release:

Category:

Kernel Functions Board:

STAMP

Processor:

BF537 Silicon Revision:

Is this bug repeatable?:

Yes Resolution:

Fixed

Uboot version or rev.:

Toolchain version or rev.:

App binary format:

N/A

Summary: System with EMAC driver enabled - Core not idling

Details:

BF537/6 using EMAC consumes approx. twice the internal power during idle.

This is caused by the system never really going into idle.

By default we enabled all bits in the SIC_IWR register, thus every activated Peripheral signaling an Interrupt to the SIC may wake up the core while in idle state.

Usually its part of the peripherals control/initialization whether they should signal an IRQ to the SIC or not.

This applies for all peripherals except for the EMAC.

None of the Bits in EMAC_TX_IRQE are set, and also DMA2 (TX) is set up without interrupts.

And still we see MAC TX constantly latched in SIC_ISR – thus causing a constant assertion of Awake from idle.

Follow-ups

--- Michael Hennerich 2008-08-06 05:59:12

Fixed on 2008R1 and svn trunk.

Resolution:

Disable all bits in SIC_IWR unless we are going into a real (DPMC) power saving

mode. Any Interrupt can wake the core form it’s idle; state.

-Michael

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