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Re: Reset of USB

To: ichinoh@mb.neweb.ne.jp
Subject: Re: Reset of USB
From: Pete Popov <ppopov@mvista.com>
Date: Tue, 31 Aug 2004 14:40:49 -0700
Cc: linux-mips@linux-mips.org
In-reply-to: <F7800BBC-FB5C-11D8-85DA-000A956B2316@mb.neweb.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <F7800BBC-FB5C-11D8-85DA-000A956B2316@mb.neweb.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mozilla Thunderbird 0.7.3 (Windows/20040803)
ichinoh@mb.neweb.ne.jp wrote:

Hello ,

I invoked the Linux kernel on ALCHEMY DBAU1100 by U-BOOT.

The processing which resets USB-OHCI of the head of a kernel is not completed. (refer to *)

Au1100 does not indicate "reset is completed."
Is this phenomenon experienced?

In addition,
this phenomenon is not encountered when starting a kernel by YAMON.

Yamon initializes the CPU and then Linux doesn't have to touch too many registers. I'm guessing u-boot doesn't setup the clocking correctly, or at all, and that might be your problem. The Yamon code for these boards is available and it's easy to read the initialization code. Take a look at it and that should solve your problem.

Pete



*:
arch/mips/au1000/common/setup.c

#ifdef CONFIG_USB_OHCI
    // enable host controller and wait for reset done
    au_writel(0x08, USB_HOST_CONFIG);
    udelay(1000);
    au_writel(0x0E, USB_HOST_CONFIG);
    udelay(1000);
    au_readl(USB_HOST_CONFIG); // throw away first read
    while (!(au_readl(USB_HOST_CONFIG) & 0x10))
        au_readl(USB_HOST_CONFIG);
#endif

Best regards,
Nyauyama




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