linux-kernel - Re: [cocci] [PATCH v3 2/6] coccinelle: misc: Add field

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Message-ID: <1e3ba498-2bfb-4cab-ba13-5ab2c5b03ef9@quicinc.com>
Date: Mon, 19 May 2025 21:44:20 +0800
From: Luo Jie <quic_luoj@...cinc.com>
To: Markus Elfring <Markus.Elfring@....de>, <cocci@...ia.fr>,
        <linux-arm-kernel@...ts.infradead.org>, <kvmarm@...ts.linux.dev>,
        "Catalin
 Marinas" <catalin.marinas@....com>,
        Joey Gouly <joey.gouly@....com>,
        "Julia
 Lawall" <Julia.Lawall@...ia.fr>, Marc Zyngier <maz@...nel.org>,
        Nicolas Palix
	<nicolas.palix@...g.fr>,
        Oliver Upton <oliver.upton@...ux.dev>,
        "Rasmus
 Villemoes" <linux@...musvillemoes.dk>,
        Suzuki Poulouse
	<suzuki.poulose@....com>,
        Will Deacon <will@...nel.org>, Yury Norov
	<yury.norov@...il.com>,
        Zenghui Yu <yuzenghui@...wei.com>
CC: LKML <linux-kernel@...r.kernel.org>, Andrew Lunn <andrew@...n.ch>,
        "Kiran
 Kumar C.S.K" <quic_kkumarcs@...cinc.com>,
        Lei Wei <quic_leiwei@...cinc.com>, Pavithra R <quic_pavir@...cinc.com>,
        Suruchi Agarwal
	<quic_suruchia@...cinc.com>,
        <quic_linchen@...cinc.com>
Subject: Re: [cocci] [PATCH v3 2/6] coccinelle: misc: Add field_modify script



On 4/24/2025 12:35 AM, Markus Elfring wrote:
> …
>>> -reg &= ~mask;
>>> -reg |= FIELD_PREP
>>> +       FIELD_MODIFY
>>>                     (mask,
>>> +                  &reg,
>>>                      val
>>>                     );
> …
>> With this code variant, there is no space prior to &reg, here is the
>> example code changes generated by the SmPL code as below, is this expected?
> …
>> +++ b/drivers/phy/starfive/phy-jh7110-dphy-tx.c
>> @@ -244,8 +244,7 @@ static int stf_dphy_configure(struct phy
>>          i = stf_dphy_get_config_index(bitrate);
>>
>>          tmp = readl(dphy->topsys + STF_DPHY_APBIFSAIF_SYSCFG(100));
>> -       tmp &= ~STF_DPHY_REFCLK_IN_SEL;
>> -       tmp |= FIELD_PREP(STF_DPHY_REFCLK_IN_SEL, STF_DPHY_REFCLK_12M);
>> +       FIELD_MODIFY(STF_DPHY_REFCLK_IN_SEL,&tmp, STF_DPHY_REFCLK_12M);
>>          writel(tmp, dphy->topsys + STF_DPHY_APBIFSAIF_SYSCFG(100));
> 
> The Coccinelle software is still evolving somehow.
> Thus your test result can trigger further development considerations.
> I hope that clarifications and corresponding improvements can be achieved
> also according to such source code layout concerns.
> 
> Regards,
> Markus

OK, understand. I will keep the original patch as below for now, as we
need to ensure the script generates code with the expected style.
+- reg &= ~mask;
+- reg |= FIELD_PREP(mask, val);
++ FIELD_MODIFY(mask, &reg, val);

In addition, below case is filed to request this improvement on the
coccinelle project.
https://github.com/coccinelle/coccinelle/issues/397

Thanks.