linux-kernel - Re: [PATCH] clk: mediatek: mt8186: Change I2C 4/5/6 ap clocks parent to infra

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Date:   Tue, 24 Oct 2023 07:47:00 +0000
From:   Yu-chang Lee (李禹璋) 
        <Yu-chang.Lee@...iatek.com>
To:     "wenst@...omium.org" <wenst@...omium.org>,
        "sboyd@...nel.org" <sboyd@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        Chun-Jie Chen (陳浚桀) 
        <Chun-Jie.Chen@...iatek.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Miles Chen (陳民樺) 
        <Miles.Chen@...iatek.com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH] clk: mediatek: mt8186: Change I2C 4/5/6 ap clocks parent
 to infra

On Tue, 2023-10-24 at 10:58 +0800, Chen-Yu Tsai wrote:
> On Tue, Oct 24, 2023 at 10:52 AM Stephen Boyd <sboyd@...nel.org>
> wrote:
> > 
> > Quoting Chen-Yu Tsai (2023-10-19 22:06:35)
> > > On Thu, Oct 19, 2023 at 8:49 PM AngeloGioacchino Del Regno
> > > <angelogioacchino.delregno@...labora.com> wrote:
> > > > 
> > > > Fix the parenting of clocks imp_iic_wrap_ap_clock_i2c{4-6}, as
> > > > those
> > > > are effectively parented to infra_ao_i2c{4-6} and not to the
> > > > I2C_AP.
> > > > This permits the correct (and full) enablement and disablement
> > > > of the
> > > > I2C4, I2C5 and I2C6 bus clocks, satisfying the whole clock tree
> > > > of
> > > > those.
> > > > 
> > > > As an example, when requesting to enable
> > > > imp_iic_wrap_ap_clock_i2c4:
> > > > 
> > > > Before: infra_ao_i2c_ap -> imp_iic_wrap_ap_clock_i2c4
> > > > After:  infra_ao_i2c_ap -> infra_ao_i2c4 ->
> > > > imp_iic_wrap_ap_clock_i2c4
> > > > 
> > > > Fixes: 66cd0b4b0ce5 ("clk: mediatek: Add MT8186 imp i2c wrapper
> > > > clock support")
> > > > Signed-off-by: AngeloGioacchino Del Regno <
> > > > angelogioacchino.delregno@...labora.com>
> > > 
> > > I'm curious about what led to discovering this error?
> > > 
> > 
> > Is that an acked-by?
> 
> MediaTek engineers are saying the original code already matches the
> documentation provided by their hardware engineers. I'm trying to get
> them to respond on the mailing list.
> 
> ChenYu
> 
After checking with I2C clock hardware designer there is no
infra_ao_i2c{4-6} clock gate in between. And the clock document at hand
aslo shows the same result. Generallly speaking, we would like to keep
sw setting align with the hardware design document. I would recommand
not to change this part of code, but enable infra_ao_i2c{4-6} prior to
the usage of imp_iic_wrap_ap_clock_i2c clock.

Best Regards,
YuChang