linux-kernel - Re: [PATCH 06/18] EDAC/amd64: Add prep_chip

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Date:   Thu, 19 May 2022 14:42:55 +0000
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org,
        Smita.KoralahalliChannabasappa@....com, muralidhara.mk@....com,
        naveenkrishna.chatradhi@....com
Subject: Re: [PATCH 06/18] EDAC/amd64: Add prep_chip_selects() into pvt->ops

On Wed, May 18, 2022 at 10:10:05AM +0200, Borislav Petkov wrote:
> On Mon, May 09, 2022 at 02:55:22PM +0000, Yazen Ghannam wrote:
> > From: Muralidhara M K <muralidhara.mk@....com>
> > 
> > GPU Nodes will need to set the number of available Chip Selects, i.e.
> > Base and Mask values, differently than existing systems. A function
> > pointer should be used rather than introduce another branching condition.
> 
> Yeah, it looks to me like all that detection logic should be split
> eventually. Looking at read_mc_regs(), it has
> 
>         if (pvt->umc) {
>                 __read_mc_regs_df(pvt);
> 
>                 goto skip;
>         }
> 
> at the top, then a whole bunch of legacy stuff and then at the skip
> label some common stuff...
> 
> Another thing you could consider is to have common functionality carved
> out into helpers with "common" in the name and then call those from both
> UMC and DCT paths. Perhaps that'll help keep the init paths sane. That
> is, short of splitting this driver.
> 
> We did the splitting for Intel and there we have a common, librarized
> code which gets linked into a couple of drivers. You don't have to do
> this too - just putting it out there as an alternative.
> 
> The per-family function pointers design could be good too, if done
> right. The advantage being, you have a single driver for all, yadda
> yadda...
>

Yep, I've actually considered splitting this driver. But I think at this point
it'd be best to keep what we have, and then write a new driver if and when a
major change happens in future platforms.

> > Prepare for this by adding prep_chip_selects() to pvt->ops and set it
> > as needed based on currently supported systems.
> > 
> > Use a "umc" prefix for modern systems, since these use Unified Memory
> > Controllers (UMCs).
> > 
> > Use a "dct" prefix for newly-defined legacy functions, since these
> > systems use DRAM Controllers (DCTs).
> > 
> > Signed-off-by: Muralidhara M K <muralidhara.mk@....com>
> > Signed-off-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@....com>
> 
> What does Naveen's SOB mean here? Co-developed-by perhaps?
>

Yes, that's right. Sorry I missed it. I'll include it in the next revision.

Thanks,
Yazen