From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Roese <sr@denx.de>
Date: Thu, 21 Oct 2010 13:03:16 +0200
Subject: [U-Boot] ELF_RELOC causes strange I-cache issues
In-Reply-To: <4CC01719.30706@free.fr>
References: <20101020184930.E89F7136320@gemini.denx.de>
	<4CC011B4.9060808@emk-elektronik.de> <4CC01719.30706@free.fr>
Message-ID: <201010211303.16760.sr@denx.de>
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To: u-boot@lists.denx.de

On Thursday 21 October 2010 12:34:01 Albert ARIBAUD wrote:
> > But with DCACHE ON, the USB Stick is not found - maybe a timing problem:
> > 
> > TOP9000>  dc off
> > Data (writethrough) Cache is OFF
> > TOP9000>  usb reset
> > (Re)start USB...
> > USB:   scanning bus for devices... 2 USB Device(s) found
> > 
> >         scanning bus for storage devices... 1 Storage Device(s) found
> > 
> > TOP9000>  dc on
> > Data (writethrough) Cache is ON
> > TOP9000>  usb reset
> > (Re)start USB...
> > USB:   scanning bus for devices... ERROR: CTL:TIMEOUT
> > 2 USB Device(s) found
> > 
> >         scanning bus for storage devices... 0 Storage Device(s) found
> > 
> > TOP9000>
> > 
> > 
> > Reinhard
> 
> If the USB controller uses DMA, then the DCache issue probably has to do
> with making sure to flush the (relevant lines of) cache before
> memory-to-device DMAs and to invalidate the (again, relevant lines of)
> cache after device-to-memory DMAs.

Correct. Note that the EHCI driver already supports such a mode with d-cache 
enabled. You need to set CONFIG_EHCI_DCACHE to enable these cache handling 
functions.
 
> And I suggest we move this dcache issue to its own discussion thread.

Yes. This should be analysed/handled independently.

Cheers,
Stefan

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