Re: [PATCH V2] AHCI: Workaround for ThunderX Errata#22536

[Tirumalesh Chalamarla]

On 02/16/2016 11:38 AM, David Daney wrote:
> On 02/16/2016 11:14 AM, Tirumalesh Chalamarla wrote:
> > On 02/16/2016 06:42 AM, Robert Richter wrote:
> > > On 15.02.16 13:30:41, Tejun Heo wrote:
> > > > On Sun, Feb 14, 2016 at 07:36:18PM -0800, Tirumalesh Chalamarla wrote:
> > > > > There is no need for special Driver, AHCI is sufficient for
> > > > > ThunderX, the
> > > > > file only contains this interrupt handler,
> > > > > is it preferable if this interrupt handler in libahci.c with others,
> > > > > instead
> > > > > of separate file?
> > > >
> > > > Yeap, just fold it in ahci.c with surrounding #ifdef guard.
> > >
> > > Yes, please use #ifdef CONFIG_CAVIUM_ERRATUM_22536 ... and add a
> > > kconfig entry for this to arch/arm64/Kconfig.
> > Are you sure, this is not a workaround that is based on alternative
> > framework rather on pci device and vendor
> >
> > do you think CONFIG_ARCH_THUNDER a good alternative?
>
> No.  CONFIG_ARCH_THUNDER should be removed all together.
>
> Grouping a bunch of unrelated features under a single config variable
> creates a very brittle system.  What are you going to do when a new
> hardware revision is released?  Create CONFIG_ARCH_THUNDER2?  Which one
> of these two would you select if building a kernel?  It is a choice that
> we don't want to force users (kernel builders) to have to waste mental
> energy on.
>
> Instead, let's try to make things work out of the box without having to
> set a bunch of random config variables.
>
> If a generic arm64 kernel won't get too bloated, I would suggest just
> enabling the compilation of the code unconditionally (at least for
> arm64).  The use of the code would still be gated by the PCI version
> probe that is part of the patch.

exactly, that is my initial choice with v1, and only depends on vendor 
and device id.

but it seems a config is needed. how about ARCH_ARM64 then?

Thanks,
Tirumalesh.

> David Daney