From: Reinhard Meyer <u-boot@emk-elektronik.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] AT91: USB and DCACHE issue (was: ELF_RELOC causes strange I-cache issues)
Date: Thu, 21 Oct 2010 13:22:10 +0200 [thread overview]
Message-ID: <4CC02262.7040809@emk-elektronik.de> (raw)
Hi,
>>> 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.
AT91 uses OHCI.
As far as I can tell there is no cache code in it.
And I am not sure whether the USB RAM is cache inhibited.
Do any other architectures work with DCACHE and OHCI?
Best Regards,
Reinhard
next reply other threads:[~2010-10-21 11:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-21 11:22 Reinhard Meyer [this message]
2010-10-21 11:31 ` [U-Boot] AT91: USB and DCACHE issue (was: ELF_RELOC causes strange I-cache issues) Stefan Roese
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