Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221009181338.2896660-8-lis8215@gmail.com> <202210100607.YdxoR0tD-lkp@intel.com>
 <CAKNVLfaFvge4A8-QUzeq-JManpuYMGvyHXCJi-ew==CWN8-M=A@mail.gmail.com>
 <bb9f79d4-82a9-4790-b849-d517333ea2d4@app.fastmail.com> <GSPOJR.M4XZ4D03G60F@crapouillou.net>
 <CAKNVLfZukazKx2yDBrLZc7J9=3cCvMgZbdghtt1YO7WivdPjvw@mail.gmail.com>
 <CAKNVLfbePJQN07GfhqAs-opm23poWsL0o-DkV=n-f9+H7Y7rpg@mail.gmail.com> <555WJR.ESJD0KDHOG3S@crapouillou.net>
In-Reply-To: <555WJR.ESJD0KDHOG3S@crapouillou.net>
From:   Siarhei Volkau <lis8215@gmail.com>
Date:   Wed, 19 Oct 2022 18:19:13 +0300
Message-ID: <CAKNVLfZ0ndwGUUq0VX3vdvxfDK6Shf61WS_dC5WocChKeYSWJg@mail.gmail.com>
Subject: Re: [PATCH 7/8] serial: 8250/ingenic: Add support for the
 JZ4750/JZ4755 SoCs
To:     Paul Cercueil <paul@crapouillou.net>
Cc:     Arnd Bergmann <arnd@arndb.de>, kernel test robot <lkp@intel.com>,
        kbuild-all@lists.01.org,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Vinod Koul <vkoul@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Linus Walleij <linus.walleij@linaro.org>,
        Jiri Slaby <jirislaby@kernel.org>, linux-clk@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        dmaengine@vger.kernel.org, linux-serial@vger.kernel.org,
        linux-mips@vger.kernel.org,
        GPIO SUBSYSTEM <linux-gpio@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

=D0=BF=D0=BD, 17 =D0=BE=D0=BA=D1=82. 2022 =D0=B3. =D0=B2 12:32, Paul Cercue=
il <paul@crapouillou.net>:
> > I checked that approach: serial seems to be working as expected,
> > but not all the time: there's a time period when the CGU driver
> > started but serial console driver is still early one.
> > In my case UART produces garbage at that period since CGU
> > needs to enable clock divider back: ext is 24MHz but 12MHz
> > required for audio codec and USB to function properly.
>
> What I'd do, is just force-enable it to 12 MHz in ingenic_fixup_fdt(),
> since the programming manual basically says that 24 MHz does not work
> properly.
>
> Then in the earlycon setup code hardcode the /2 divider with a big fat
> comment about why it's there.

Agree, the vendor's kernel does that as well.

Also I found that:
1. Many other drivers compile the early console only when
CONFIG_SERIAL_8250_CONSOLE is set.
2. All the early ingenic_ functions can be labeled as __init.
Shall I fix that while I'm already here?