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From:   Kevin Hilman <khilman@baylibre.com>
To:     Rex-BC Chen <rex-bc.chen@mediatek.com>, rafael@kernel.org,
        viresh.kumar@linaro.org, robh+dt@kernel.org, krzk+dt@kernel.org
Cc:     matthias.bgg@gmail.com, jia-wei.chang@mediatek.com,
        roger.lu@mediatek.com, hsinyi@google.com, linux-pm@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com
Subject: Re: [PATCH V2 10/15] cpufreq: mediatek: Make sram regulator optional
In-Reply-To: <be86691b529dd691203fbb5b35f8572e7e9119a8.camel@mediatek.com>
References: <20220408045908.21671-1-rex-bc.chen@mediatek.com>
 <20220408045908.21671-11-rex-bc.chen@mediatek.com>
 <7ho81b5n9v.fsf@baylibre.com>
 <be86691b529dd691203fbb5b35f8572e7e9119a8.camel@mediatek.com>
Date:   Thu, 14 Apr 2022 10:20:01 -0700
Message-ID: <7hfsmf37lq.fsf@baylibre.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Rex-BC Chen <rex-bc.chen@mediatek.com> writes:

> On Fri, 2022-04-08 at 13:32 -0700, Kevin Hilman wrote:
>> Rex-BC Chen <rex-bc.chen@mediatek.com> writes:
>> 
>> > From: Jia-Wei Chang <jia-wei.chang@mediatek.com>
>> > 
>> > For some MediaTek SoCs, like MT8186, it's possible that the sram
>> > regulator
>> > is shared between CPU and CCI.
>> > 
>> > Signed-off-by: Jia-Wei Chang <jia-wei.chang@mediatek.com>
>> 
>> nit: missing your sign-off.
>> 
>> > ---
>> >  drivers/cpufreq/mediatek-cpufreq.c | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> > 
>> > diff --git a/drivers/cpufreq/mediatek-cpufreq.c
>> > b/drivers/cpufreq/mediatek-cpufreq.c
>> > index 9e9bce0ff235..8f688d47e64b 100644
>> > --- a/drivers/cpufreq/mediatek-cpufreq.c
>> > +++ b/drivers/cpufreq/mediatek-cpufreq.c
>> > @@ -435,7 +435,7 @@ static int mtk_cpu_dvfs_info_init(struct
>> > mtk_cpu_dvfs_info *info, int cpu)
>> >  	}
>> >  
>> >  	/* Both presence and absence of sram regulator are valid cases.
>> > */
>> > -	info->sram_reg = regulator_get_exclusive(cpu_dev, "sram");
>> > +	info->sram_reg = regulator_get_optional(cpu_dev, "sram");
>> 
>> The changelog says that this regulator may be shared with CCI, so I
>> understand it's no longer exclusive.  But here you make it optional,
>> which should be explained in the changelog.  If it's not actually
>> optional, then it should just be normal "get".
>> 
>> Kevin
>
> Hello Kevin,
>
> Since cpufreq and cci devfreq might share the same sram regulator in
> MediaTek SoC, it is no longer exclusive as you mentioned.
>
> The reason to use regulator_get_optional is we hope regulator framework
> can return error for error handling rather than a dummy handler from
> regulator_get api.
>
> I will add this to commit message in next version.

OK, sounds good.

Thanks,

Kevin