linux-kernel - Re: [PATCH v7 3/3] arm64: dts: ti: k3-j7200: Add support for higher speed modes and update delay select values for MMCSD subsystems

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Date:   Tue, 23 Mar 2021 13:45:37 +0530
From:   Aswath Govindraju <a-govindraju@...com>
To:     Kishon Vijay Abraham I <kishon@...com>, Nishanth Menon <nm@...com>
CC:     Vignesh Raghavendra <vigneshr@...com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 3/3] arm64: dts: ti: k3-j7200: Add support for higher
 speed modes and update delay select values for MMCSD subsystems

Hi Kishon,

On 23/03/21 11:59 am, Kishon Vijay Abraham I wrote:
> Hi Aswath,
> 
> On 23/03/21 10:54 am, Aswath Govindraju wrote:
>> Hi Nishanth,
>>
>> On 22/03/21 9:05 pm, Nishanth Menon wrote:
>>> On 18:42-20210322, Aswath Govindraju wrote:
>>>> The following speed modes are now supported in J7200 SoC,
>>>> - HS200 and HS400 modes at 1.8 V card voltage, in MMCSD0 subsystem [1].
>>>> - UHS-I speed modes in MMCSD1 subsystem [1].
>>>>
>>>> Add support for UHS-I modes by adding voltage regulator device tree nodes
>>>> and corresponding pinmux details, to power cycle and voltage switch cards.
>>>> Set respective tags in sdhci0 and remove no-1-8-v tag from sdhci1
>>>> device tree nodes.
>>>>
>>>> Also update the delay values for various speed modes supported, based on
>>>> the revised january 2021 J7200 datasheet[2].
>>>>
>>>> [1] - section 12.3.6.1.1 MMCSD Features, in
>>>>       https://www.ti.com/lit/ug/spruiu1a/spruiu1a.pdf,
>>>>       (SPRUIU1A – JULY 2020 – REVISED JANUARY 2021)
>>>>
>>>> [2] - https://www.ti.com/lit/ds/symlink/dra821u.pdf,
>>>>       (SPRSP57B – APRIL 2020 – REVISED JANUARY 2021)
>>>>
>>>> Signed-off-by: Aswath Govindraju <a-govindraju@...com>
>>>> ---
>>>>  .../dts/ti/k3-j7200-common-proc-board.dts     | 42 +++++++++++++++++++
>>>>  arch/arm64/boot/dts/ti/k3-j7200-main.dtsi     | 14 ++++++-
>>>>  2 files changed, 54 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts b/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
>>>> index b493f939b09a..de8c06bdc825 100644
>>>> --- a/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
>>>> +++ b/arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts
>>>> @@ -16,6 +16,29 @@
>>>>  		stdout-path = "serial2:115200n8";
>>>>  		bootargs = "console=ttyS2,115200n8 earlycon=ns16550a,mmio32,0x02800000";
>>>>  	};
>>>> +
>>>> +	vdd_mmc1: fixedregulator-sd {
>>>> +		compatible = "regulator-fixed";
>>>> +		regulator-name = "vdd_mmc1";
>>>> +		regulator-min-microvolt = <3300000>;
>>>> +		regulator-max-microvolt = <3300000>;
>>>> +		regulator-boot-on;
>>>> +		enable-active-high;
>>>> +		gpios = <&exp2 2 GPIO_ACTIVE_HIGH>;
>>>
>>> is that gpio ?
>>
>> Yes, that is correct. I'll correct it in the respin
>>
>>> I'd encourage to use vin-supply as well.
>>
>> Will add this in respin.
>>
>>>
>>>> +	};
>>>> +
>>>> +	vdd_sd_dv: gpio-regulator-vdd-sd-dv {
>>> 	What does this drive? TLV71033 ?
>>
>> Yes, this node models the TLV71033 voltage regulator that switches the
>> MMC IO signal voltage level between 3.3V and 1.8V.
> 
> Nope. Unlike J721e SOM which uses TLV71033 for switching voltage, J7200
> SOM directly uses GPIO input to PMIC to control the output voltage. So
> this should model the gpio input to PMIC.
> 

This was the case with older SoMs and on newer ones load switches are
being used[1].

[1] - https://www.ti.com/lit/zip/sprr424, PROC105E6(001)_SCH.pdf, page 24

Thanks,
Aswath