linux-kernel - Re: [PATCH 4/4] edac, amd64

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Date:	Thu, 2 Oct 2014 16:52:01 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
Cc:	bhelgaas@...gle.com, linux-pci@...r.kernel.org, tglx@...utronix.de,
	hpa@...or.com, x86@...nel.org, bp@...e.de,
	dan.carpenter@...cle.com, dougthompson@...ssion.com,
	m.chehab@...sung.com, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] edac, amd64_edac: Add F15h M60h support

On Wed, Oct 01, 2014 at 02:44:21PM -0500, Aravind Gopalakrishnan wrote:
> The more I think about this, I'm finding it's hard to do this cleanly.
> I initially thought I'd just cache this in pvt->dram_type the first time I'm
> doing this.
> But, the pvt->ops->dbam_to_cs() mappers get called first before
> determine_memory_type().
> 
> So, If I look for dram_type in f15_m60h_dbam_to_chip_select() it's ugly as
> that's really the point of
> having a determine_memory_type().
> 
> Also, there's just a lot of if-else statements in determine_memory_type()
> now.
> This could benefit from having a per-family low_ops function.
> And, we can call this early... somewhere in read_mc_regs() so that we have
> information ready to use in
> f15_m60h_dbam_to_chip_select() and in init_csrows() which needs dram_type
> too.

Right, this is what I was thinking too: somewhere in read_mc_regs(),
after having collected ->dclr0, you call determine_memory_type() and
store it into pvt->dram_type.

> Oh, btw- We can do away with a pvt->dram_ctrl as
> f15_m60h_dbam_to_chip_select() really just needs the dram_type.

Yes, you make the read of DRAM_CONTROL inside determine_memory_type() as
we don't need it anywhere else.

If we do, all of a sudden, we'll move it up to read_mc_regs(). IOW, I'm
trying to centralize all reg reads in read_mc_regs() and use locally
cached info later so I don't have to access the hardware each time
needlessly, if it can be helped.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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