linux-kernel - Re: [PATCH 13/21] arc: dma-mapping: skip invalidating before bidirectional DMA

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Message-ID: <ba0c6b04-cb7d-87ba-a435-919a910282dd@synopsys.com>
Date:   Thu, 6 Apr 2023 09:01:15 +0000
From:   Shahab Vahedi <Shahab.Vahedi@...opsys.com>
To:     Vineet Gupta <vgupta@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Arnd Bergmann <arnd@...db.de>,
        Russell King <linux@...linux.org.uk>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Brian Cain <bcain@...cinc.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Stafford Horne <shorne@...il.com>,
        Helge Deller <deller@....de>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Rich Felker <dalias@...c.org>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        "David S. Miller" <davem@...emloft.net>,
        Max Filippov <jcmvbkbc@...il.com>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-oxnas@...ups.io" <linux-oxnas@...ups.io>,
        "linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>,
        "linux-hexagon@...r.kernel.org" <linux-hexagon@...r.kernel.org>,
        "linux-m68k@...ts.linux-m68k.org" <linux-m68k@...ts.linux-m68k.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "linux-openrisc@...r.kernel.org" <linux-openrisc@...r.kernel.org>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
        "linux-xtensa@...ux-xtensa.org" <linux-xtensa@...ux-xtensa.org>,
        Shahab Vahedi <Shahab.Vahedi@...opsys.com>
Subject: Re: [PATCH 13/21] arc: dma-mapping: skip invalidating before
 bidirectional DMA

On 4/2/23 08:52, Vineet Gupta wrote:
> CC Shahab
> 
> On 3/27/23 17:43, Arnd Bergmann wrote:
>> From: Arnd Bergmann<arnd@...db.de>
>>
>> Some architectures that need to invalidate buffers after bidirectional
>> DMA because of speculative prefetching only do a simpler writeback
>> before that DMA, while architectures that don't need to do the second
>> invalidate tend to have a combined writeback+invalidate before the
>> DMA.
>>
>> arc is one of the architectures that does both, which seems unnecessary.
>>
>> Change it to behave like arm/arm64/xtensa instead, and use just a
>> writeback before the DMA when we do the invalidate afterwards.
>>
>> Signed-off-by: Arnd Bergmann<arnd@...db.de>
> 
> Reviewed-by: Vineet Gupta <vgupta@...nel.org>
> 
> Shahab can you give this a spin on hsdk - run glibc testsuite over ssh
> and make sure nothing strange happens.
> 
> Thx,
> -Vineet

Tested-by: Shahab Vahedi <shahab@...opsys.com>

No regression was observed for the ARC target before and after applying
these 21 patches. The test environment and its summary follow.

board:  ARC HSDK
base:   repo:   linux-next
        tag:    next-20230403
        commit: 31bd35b66249 Add linux-next specific files for 20230403
hotfix: net: stmmac: check fwnode for phy device before scanning for phy [1]
glibc:  2.37

Summary of test results:
     20 FAIL
   4227 PASS
     38 UNSUPPORTED
     16 XFAIL
      2 XPASS

[1]
https://lore.kernel.org/lkml/20230405093945.3549491-1-michael.wei.hong.sit@intel.com/#r

-- 
Shahab