Date:   Mon, 6 Mar 2023 23:12:54 +0300
From:   Dmitry Rokosov <ddrokosov@sberdevices.ru>
To:     Jerome Brunet <jbrunet@baylibre.com>
CC:     <neil.armstrong@linaro.org>, <mturquette@baylibre.com>,
        <sboyd@kernel.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <khilman@baylibre.com>,
        <martin.blumenstingl@googlemail.com>, <jian.hu@amlogic.com>,
        <kernel@sberdevices.ru>, <rockosov@gmail.com>,
        <linux-amlogic@lists.infradead.org>, <linux-clk@vger.kernel.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v9 1/5] clk: meson: add support for A1 PLL clock ops
Message-ID: <20230306201254.tgyfztzqukzzeaqi@CAB-WSD-L081021>
References: <20230301183759.16163-1-ddrokosov@sberdevices.ru>
 <20230301183759.16163-2-ddrokosov@sberdevices.ru>
 <1jy1oab06v.fsf@starbuckisacylon.baylibre.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <1jy1oab06v.fsf@starbuckisacylon.baylibre.com>
User-Agent: NeoMutt/20220415
Precedence: bulk

On Mon, Mar 06, 2023 at 12:09:35PM +0100, Jerome Brunet wrote:
> 
> On Wed 01 Mar 2023 at 21:37, Dmitry Rokosov <ddrokosov@sberdevices.ru> wrote:
> 
> > From: Jian Hu <jian.hu@amlogic.com>
> >
> > Modern meson PLL IPs are a little bit different from early known PLLs.
> > The main difference is located in the init/enable/disable sequences; the
> > rate logic is the same.
> 
> For the record, I find very odd that PLLs used to have an 'rst' bit in
> CTRL0:29 (see g12 for example), this bit goes un-documented in the a1
> datasheet, and following SoCs like s4 still have a rst bit, still in
> CTRL0:29
> 
> I would not be surpized if the rst is actually still there in the a1.
> It is just my guess ...
> 

We don't know it for sure. Datasheet doesn't have any information about
CTRL0:29 bit, CTRL0:28 (enable) bit is last one I see.
Vendor Amlogic driver doesn't have it in the init sequence as well.
BTW, vendor driver doesn't use clk_pll common logic, it achieves PLL
power-on goals using init_regs sequence.

> > Compared with the previous SoCs, self-adaption current module
> > is newly added for A1, and there is no reset parameter except the
> > fixed pll. In A1 PLL, the PLL enable sequence is different, using
> > the new power-on sequence to enable the PLL.
> 
> Please split this patch:
> #1 make the rst optional (if you must)
> #2 add the self current adapt param.
> 
> Apart from this, it looks good
> 

Thank you, I'll split it in the next version!

[...]
-- 
Thank you,
Dmitry