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Re: ALCHEMY: AU1200 USB Host Controller (OHCI/EHCI)

To: "Matej Kupljen" <matej.kupljen@ultra.si>
Subject: Re: ALCHEMY: AU1200 USB Host Controller (OHCI/EHCI)
From: "Matthias Lenk" <matthias.lenk@amd.com>
Date: Wed, 4 Jan 2006 13:32:15 +0100
Cc: "Jordan Crouse" <jordan.crouse@amd.com>, linux-mips@linux-mips.org, linux-usb-devel@lists.sourceforge.net
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Hi Matej ,

I looked into the issue and came to the same conclusions as you. Something 
significant has changed from 2.6.15rc2 (what the patch was made for) to 
2.6.15rc5. I added the initialization of the caps and regs fields of the ehci 
structure to the probe function in ehci-au1xxx.c. The driver doesn't crash 
anymore but does not work either.

I also tried the Au1xxx OHCI and it hangs while loading the module with rc7. 
So it'll probably take some time to port the Au1200 EHCI and OHCI drivers to 
2.6.15rc7 (again!). 

Any hints on what has changed are appreciated.

Thanks,

Matthias

On Wednesday 04 January 2006 13:12, Matej Kupljen wrote:
> Hi
>
> (After some confusion about kernel version, I think I found the
> problem, sorry about that).
>
> I used binutils 2.15 and 2.16.1, but did not work.
>
> The code in the ehci-hcd.c looks like this:
> ---------------------------------------------------------------------------
>- ehci->periodic_size = DEFAULT_I_TDPS;
>       if ((retval = ehci_mem_init(ehci, GFP_KERNEL)) < 0)
>               return retval;
>
>       /* controllers may cache some of the periodic schedule ... */
>       hcc_params = readl(&ehci->caps->hcc_params);
>       if (HCC_ISOC_CACHE(hcc_params))         // full frame cache
>               ehci->i_thresh = 8;
>       else                                    // N microframes cached
>               ehci->i_thresh = 2 + HCC_ISOC_THRES(hcc_params);
> ---------------------------------------------------------------------------
>-
>
> The problem is *AFTER* the call to ehci_mem_init, where a read from
> ehci->caps->hcc_params is attempted, but caps is NULL.
>
> This can be seen by this assembly code form Insight:
> ---------------------------------------------------------------------------
>- 0x80350758   jal     0x802a3f40 <memset>
> 0x8035075c    sll     a2,a2,0x2
> 0x80350760    lw      v1,0(s0)
> 0x80350764    lw      a2,8(v1)
>
> s0 points to ehci
> at offset 0 from ehci is caps
> and at offset 8 from caps is hcc_params
> ---------------------------------------------------------------------------
>-
>
> Where should the caps be initialized?
> The only place, where it is set in drivers/usb/ is in
> drivers/usb/host/ehci-pci.c:
> ---------------------------------------------------------------------------
>- /* called during probe() after chip reset completes */
> static int ehci_pci_setup(struct usb_hcd *hcd)
> {
>         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
>         struct pci_dev          *pdev =
> to_pci_dev(hcd->self.controller);
>         u32                     temp;
>         int                     retval;
>
>         ehci->caps = hcd->regs;
> ---------------------------------------------------------------------------
>- But the ehci-pci.c is not included in the compilation, because at the end
> of ehci-hcd.c we find:
> ---------------------------------------------------------------------------
>- #if defined(CONFIG_SOC_AU1X00)
> #include "ehci-au1xxx.c"
> #elif defined(CONFIG_PCI)
> #include "ehci-pci.c"
> #else
> #error "missing bus glue for ehci-hcd"
> #endif
> ---------------------------------------------------------------------------
>-
>
> What should be done?
> I hope this helps.
>
> BR,
> Matej


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