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

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Date:   Thu, 13 Oct 2022 06:37:39 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Jisheng Zhang <jszhang@...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 8 October 2022 14:59:37 IST, Jisheng Zhang <jszhang@...nel.org> wrote:
>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.

Given this comment and the LKP report I've marked the series as changes requested in patchwork FYI.

Thanks,
Conor.

>
>> 
>> 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
>> >