linux-kernel - Re: [PATCH 1/8] riscv: move riscv_noncoherent

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Date:   Sat, 8 Oct 2022 21:59:37 +0800
From:   Jisheng Zhang <jszhang@...nel.org>
To:     Conor Dooley <conor@...nel.org>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/8] riscv: move riscv_noncoherent_supported() out of
 ZICBOM probe

On Sat, Oct 08, 2022 at 02:06:00PM +0100, Conor Dooley wrote:
> On Thu, Oct 06, 2022 at 03:08:11PM +0800, Jisheng Zhang wrote:
> > It's a bit wired to call riscv_noncoherent_supported() once when
> > insmod a module. Move the calling out of feature patch func.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> > ---
> >  arch/riscv/kernel/cpufeature.c | 7 +------
> >  arch/riscv/kernel/setup.c      | 4 ++++
> >  2 files changed, 5 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index 3b5583db9d80..03611b3ef45e 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -272,12 +272,7 @@ static bool __init_or_module cpufeature_probe_zicbom(unsigned int stage)
> >  	case RISCV_ALTERNATIVES_EARLY_BOOT:
> >  		return false;
> >  	default:
> > -		if (riscv_isa_extension_available(NULL, ZICBOM)) {
> > -			riscv_noncoherent_supported();
> > -			return true;
> > -		} else {
> > -			return false;
> > -		}
> > +		return riscv_isa_extension_available(NULL, ZICBOM);
> >  	}
> >  #endif
> >  
> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > index 2dfc463b86bb..1a055c3f5d9d 100644
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -299,6 +299,10 @@ void __init setup_arch(char **cmdline_p)
> >  	riscv_init_cbom_blocksize();
> >  	riscv_fill_hwcap();
> >  	apply_boot_alternatives();
> > +#ifdef CONFIG_RISCV_DMA_NONCOHERENT
> > +	if (riscv_isa_extension_available(NULL, ZICBOM))
> > +		riscv_noncoherent_supported();
> > +#endif
> 
> I have a personal bias against ifdefs where possible, maybe @Heiko
> remembers why riscv_noncoherent_supported() was not defined as something
> like `void riscv_noncoherent_support(void){}` for when that CONFIG is
> not enabled? If it was this could become a an IS_ENABLED & we wouldn't
> have to be so careful about wrapping it's usage in ifdefs.

Good idea. Will do in newer version.

> 
> Your change in isolation makes sense to me though, so:
> Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> 
> Thanks,
> Conor.
> 
> >  }
> >  
> >  static int __init topology_init(void)
> > -- 
> > 2.37.2
> >