linux-kernel - Re: [PATCH 5/7] cpufreq: qcom-hw: Use regmap for accessing hardware registers

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Message-ID: <20200908111813.bbgfxo5v7qt6ujpc@vireshk-i7>
Date:   Tue, 8 Sep 2020 16:48:13 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     rjw@...ysocki.net, robh+dt@...nel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, amitk@...nel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        dmitry.baryshkov@...aro.org, tdas@...eaurora.org
Subject: Re: [PATCH 5/7] cpufreq: qcom-hw: Use regmap for accessing hardware
 registers

On 08-09-20, 16:41, Manivannan Sadhasivam wrote:
> On 0908, Viresh Kumar wrote:
> > On 08-09-20, 13:27, Manivannan Sadhasivam wrote:
> > > Use regmap for accessing cpufreq registers in hardware.
> > 
> > Why ? Please mention why a change is required in the log.
> > 
> 
> Only because it is recommended to use regmap for abstracting the hw access.

Yes it can be very useful in abstracting the hw access in case of
busses like SPI/I2C, others, but in this case there is only one way of
doing it with the exact same registers. I am not sure it is worth it
here. FWIW, I have never played with regmaps personally, and so every
chance I can be wrong here.

> Moreover it handles the proper locking for us in the core (spinlock vs mutex).

What locking do you need here ?

> I've seen many subsystem maintainers prefer regmap over plain readl/writel
> calls. I'll add the reason in commit log.

I am not sure if it is worth it here.

-- 
viresh