From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
To: Konrad Dybcio <konrad.dybcio@linaro.org>,
Stephan Gerhold <stephan@gerhold.net>
Cc: agross@kernel.org, andersson@kernel.org, djakov@kernel.org,
robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
benl@squareup.com, shawn.guo@linaro.org,
fabien.parent@linaro.org, leo.yan@linaro.org,
dmitry.baryshkov@linaro.org
Subject: Re: [PATCH v4 0/6] Add MSM8939 SoC support with two devices
Date: Thu, 26 Jan 2023 16:45:41 +0000 [thread overview]
Message-ID: <ff3aebd7-2932-fd9f-3e82-fe123b770a87@linaro.org> (raw)
In-Reply-To: <b7343ea6-7194-e709-8fed-4a1a17f7beb5@linaro.org>
On 26/01/2023 16:32, Bryan O'Donoghue wrote:
> The only input clock to GCC is XO or buffered CXO if routed through the
> PMIC.
>
> You can select via GCC::RCGR where dsiX_phy_pll_out_byteclk is *sourced*
> from XO, GPLL0_AUX or P_DSI0_PHYPLL_BYTE.
>
> So, obvs the byte clock can be any one of those input sources.
>
> But the question is, if you select dsi0_phy_pll_out_byteclk - what
> provides it ?
>
> Reviewing the LK bootloader for 3.18, it *looks* to me like the dsi0 pll
> is always switched on. The downstream kernel tree doesn't represent that.
>
> 0x01A9811C MDSS_DSI_0_CLK_CTRL
> Type: RW
> Reset State: 0x00000000 -> BIT(4) -> Turns on/off BYTECLK for the DSI.
> If set to 1, clock is ON.
>
> Hmm. I think actually it must be the case that DSI1 is a slave of DSI0.
* If and only if you set P_DSI0_PHYPLL_BYTE::SRC_SEL = 0x01, using
SRC_SEL = 0 (XO) or SRC_SEL = 0x02 (GPLL0_AUX) should negate the dependency.
I'll review downstream further - perhaps DSI1 in practice doesn't set
P_DSI0_PHYPLL_BYTE as the source clock..
---
bod
prev parent reply other threads:[~2023-01-26 16:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-23 2:31 [PATCH v4 0/6] Add MSM8939 SoC support with two devices Bryan O'Donoghue
2023-01-23 2:31 ` [PATCH v4 1/6] dt-bindings: clock: msm8939: Move msm8939 to a distinct yaml file Bryan O'Donoghue
2023-01-23 9:06 ` Krzysztof Kozlowski
2023-01-23 13:49 ` Rob Herring
2023-01-23 2:31 ` [PATCH v4 2/6] dt-bindings: interconnect: Exclude all non msm8939 from snoc-mm Bryan O'Donoghue
2023-01-23 2:31 ` [PATCH v4 3/6] arm64: dts: qcom: Add msm8939 SoC Bryan O'Donoghue
2023-01-23 2:31 ` [PATCH v4 4/6] arm64: dts: qcom: Add msm8939-pm8916.dtsi include Bryan O'Donoghue
2023-01-23 2:31 ` [PATCH v4 5/6] arm64: dts: qcom: Add Square apq8039-t2 board Bryan O'Donoghue
2023-01-23 16:17 ` Konrad Dybcio
2023-01-23 16:29 ` Krzysztof Kozlowski
2023-01-25 1:21 ` Bryan O'Donoghue
2023-01-25 1:29 ` Konrad Dybcio
2023-01-25 2:25 ` Bryan O'Donoghue
2023-01-25 7:15 ` Krzysztof Kozlowski
2023-01-23 2:31 ` [PATCH v4 6/6] arm64: dts: qcom: Add msm8939 Sony Xperia M4 Aqua Bryan O'Donoghue
2023-01-23 16:19 ` Konrad Dybcio
2023-01-23 11:00 ` [PATCH v4 0/6] Add MSM8939 SoC support with two devices Bryan O'Donoghue
2023-01-23 11:08 ` Bryan O'Donoghue
2023-01-23 12:49 ` Stephan Gerhold
2023-01-23 13:03 ` Bryan O'Donoghue
2023-01-23 13:23 ` Bryan O'Donoghue
2023-01-23 14:00 ` Stephan Gerhold
2023-01-23 16:14 ` Bryan O'Donoghue
2023-01-23 16:21 ` Konrad Dybcio
2023-01-23 16:29 ` Bryan O'Donoghue
2023-01-26 15:29 ` Bryan O'Donoghue
2023-01-26 15:34 ` Konrad Dybcio
2023-01-26 16:32 ` Bryan O'Donoghue
2023-01-26 16:45 ` Bryan O'Donoghue [this message]
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