linux-kernel - Re: [PATCH v5 0/3] Amlogic 32-bit Meson SoC SDHC MMC controller driver

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Date:   Mon, 27 Apr 2020 18:23:49 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     Jerome Brunet <jbrunet@...libre.com>
Cc:     linux-amlogic@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-mmc@...r.kernel.org, ulf.hansson@...aro.org,
        robh+dt@...nel.org, mark.rutland@....com, jianxin.pan@...ogic.com,
        linux-kernel@...r.kernel.org, yinxin_1989@...yun.com,
        linux-arm-kernel@...ts.infradead.org, lnykww@...il.com
Subject: Re: [PATCH v5 0/3] Amlogic 32-bit Meson SoC SDHC MMC controller driver

Hi Jerome,

On Mon, Apr 27, 2020 at 10:56 AM Jerome Brunet <jbrunet@...libre.com> wrote:
[...]
> > Changes since v3 at [3]:
> > - split the clock bits into a separate clock controller driver because
> >   of two reasons: 1) it keeps the MMC controller driver mostly clean of
> >   the clock bits
>
> If the register is in the MMC controller register space and the MMC
> driver is the driver using these clocks, it is where the clocks belong.
> I don't get why it could be an issue ?
>
> Is the clock block is shared with another device, like on the Gx family ?
no, it is not shared with another device (to my knowledge).

> > 2) the pure clock controller can use
> >   devm_clk_hw_register() (instead of devm_clk_register(), which is
> >   deprecated) and the MMC controller can act as a pure clock consumer.
>
> Why can't you use devm_clk_hw_register in an MMC driver ?
> Unless I missed something, it is provided by clk-provider.h, which can be
> included by any driver.
indeed, I could use devm_clk_hw_register in the MMC driver.
Ulfs concern was that a lot of code was needed for managing the clocks
and I agree with him. so this is my way of keeping those details away
from the MMC driver and have two separate drivers which are better to
understand overall.


Martin