[coreboot] BDX-DE PCI init fail

[Hilbert Tu(杜睿哲_Pegatron)]

Hi David,

Yes, actually I have same try like you to comment out the SMBus clock gating. But the result is it started to reboot again after jumping to boot code as attached. I use U-Boot as payload. If grub was used, it just hanged there. Did you have same condition before? Thanks.

-Hilbert

From: David Hendricks [mailto:david.hendricks at gmail.com]
Sent: Thursday, January 04, 2018 7:56 AM
To: Hilbert Tu(杜睿哲_Pegatron)
Cc: Zoran Stojsavljevic; coreboot at coreboot.org
Subject: Re: [coreboot] BDX-DE PCI init fail

Hi Hilbert,

On Wed, Jan 3, 2018 at 12:56 AM, Hilbert Tu(杜睿哲_Pegatron) <Hilbert_Tu at pegatroncorp.com<mailto:Hilbert_Tu at pegatroncorp.com>> wrote:
Hi Zoran,

I have changed to maximal log level and found SMBus init was failed when enabling clock gating. Do you have any comments about this? Thanks.

Yes, looking back at my notes from earlier that is also how I got past the issue - by commenting out the following lines in src/soc/intel/fsp_broadwell_de/smbus.c:
        /* Enable clock gating */
       reg32 =read32(rcba + 0x341c);
       reg32 |= (1 << 5);
       write32(rcba + 0x341c, reg32);
I suspected that reading the register is where it hung, however I did not have a chance to root cause the issue or try to enable clock gating elsewhere. The system worked without clock gating enabled, though.

I also tested another Broadwell-DE device that did not require the same hack, but it used different memory and a different processor stepping (stepping 3 instead of stepping 4) which may have made a difference.

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