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ARM: dts: qcom: Add uses_level_shifter for sun

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When this "qcom,uses_level_shifter" DT entry is present
but "qcom,external-fb-clk" is not present, the SD card's
HS50 mode is run at 37.5MHz clock. This is to work around
a latency issue caused by the addition of the Level Shifter
logic. In order to use the 50MHz clock in HS50 mode, there
are two ways:
- Keep "qcom,uses_level_shifter" and "qcom,external-fb-clk"
  and make sure the Feedback Clock (FB CLK) connection between
  the Level Shifter and the MSM must be good.

- Remove "qcom,uses_level_shifter" from DT.

Please note that the "qcom,external-fb-clk" depends on
"qcom,uses_level_shifter", only set "qcom,external-fb-clk"
would not take effect.

Change-Id: Ib3a4cf5c9c20e2094556c3196d91b7e9723e0a1e
Signed-off-by: Ziqi Chen <quic_ziqichen@quicinc.com>
This commit is contained in:
Ziqi Chen
2023-08-17 01:39:23 -07:00
parent 46406e9db9
commit e4199f6cf9
3 changed files with 6 additions and 0 deletions
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2
qcom/sun-mtp.dtsi
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@@ -244,4 +244,6 @@
resets = <&gcc GCC_SDCC2_BCR>;
reset-names = "core_reset";
qcom,uses_level_shifter;
};