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;
Message-ID: <7d67cd32-50c7-e021-c9f8-b0aa331b6c3c@collabora.com>
Date:   Tue, 13 Dec 2022 12:25:26 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.5.1
Subject: Re: [PATCH 3/4] arm64: dts: mediatek: mt8195: Fix systimer 13 MHz
 clock description
Content-Language: en-US
To:     Chen-Yu Tsai <wenst@chromium.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        =?UTF-8?Q?N=c3=adcolas_F_=2e_R_=2e_A_=2e_Prado?= 
        <nfraprado@collabora.com>
References: <20221201084229.3464449-1-wenst@chromium.org>
 <20221201084229.3464449-4-wenst@chromium.org>
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
In-Reply-To: <20221201084229.3464449-4-wenst@chromium.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Il 01/12/22 09:42, Chen-Yu Tsai ha scritto:
> The systimer block derives its 13 MHz clock by dividing the main 26 MHz
> oscillator clock by 2 internally, not through the TOPCKGEN clock
> controller.
> 
> On the MT8195 this divider is set either by power-on-reset or by the
> bootloader. The bootloader may then make the divider unconfigurable to,
> but can be read out by, the operating system.
> 
> Making the systimer block take the 26 MHz clock directly requires
> changing the implementations. As an ABI compatible fix, change the
> input clock of the systimer block a fixed factor divide-by-2 clock
> that takes the 26 MHz oscillator as its input.
> 
> Fixes: 37f2582883be ("arm64: dts: Add mediatek SoC mt8195 and evaluation board")
> Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>