linux-kernel - Re: [PATCH 3/9] regulator: mt6358: Merge VCN33

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Date:   Fri, 9 Jun 2023 16:56:05 +0100
From:   Conor Dooley <conor@...nel.org>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/9] regulator: mt6358: Merge VCN33_* regulators

On Fri, Jun 09, 2023 at 04:30:00PM +0800, Chen-Yu Tsai wrote:
> The VCN33_BT and VCN33_WIFI regulators are actually the same regulator,
> having the same voltage setting and output pin. There are simply two
> enable bits that are ORed together to enable the regulator.
> 
> Having two regulators representing the same output pin is misleading
> from a design matching standpoint, and also error-prone in driver
> implementations. If consumers try to set different voltages on either
> regulator, the one set later would override the one set before. There
> are ways around this, such as chaining them together and having the
> downstream one act as a switch. But given there's only one output pin,
> such a workaround doesn't match reality.
> 
> Remove the VCN33_WIFI regulator. During the probe phase, have the driver
> sync the enable status of VCN33_WIFI to VCN33_BT. Also drop the suffix
> so that the regulator name matches the pin name in the datasheet.
> 
> Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> ---
>  drivers/regulator/mt6358-regulator.c       | 65 +++++++++++++++++-----
>  include/linux/regulator/mt6358-regulator.h |  6 +-
>  2 files changed, 52 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/regulator/mt6358-regulator.c b/drivers/regulator/mt6358-regulator.c
> index c9e16bd092f6..faf6b0757019 100644
> --- a/drivers/regulator/mt6358-regulator.c
> +++ b/drivers/regulator/mt6358-regulator.c
> @@ -277,7 +277,7 @@ static const unsigned int vcama_voltages[] = {
>  	2800000, 2900000, 3000000,
>  };
>  
> -static const unsigned int vcn33_bt_wifi_voltages[] = {
> +static const unsigned int vcn33_voltages[] = {
>  	3300000, 3400000, 3500000,
>  };
>  
> @@ -321,7 +321,7 @@ static const u32 vcama_idx[] = {
>  	0, 7, 9, 10, 11, 12,
>  };
>  
> -static const u32 vcn33_bt_wifi_idx[] = {
> +static const u32 vcn33_idx[] = {
>  	1, 2, 3,
>  };
>  
> @@ -566,12 +566,8 @@ static struct mt6358_regulator_info mt6358_regulators[] = {
>  		   MT6358_LDO_VCAMA1_CON0, 0, MT6358_VCAMA1_ANA_CON0, 0xf00),
>  	MT6358_LDO("ldo_vemc", VEMC, vmch_vemc_voltages, vmch_vemc_idx,
>  		   MT6358_LDO_VEMC_CON0, 0, MT6358_VEMC_ANA_CON0, 0x700),
> -	MT6358_LDO("ldo_vcn33_bt", VCN33_BT, vcn33_bt_wifi_voltages,
> -		   vcn33_bt_wifi_idx, MT6358_LDO_VCN33_CON0_0,
> -		   0, MT6358_VCN33_ANA_CON0, 0x300),
> -	MT6358_LDO("ldo_vcn33_wifi", VCN33_WIFI, vcn33_bt_wifi_voltages,
> -		   vcn33_bt_wifi_idx, MT6358_LDO_VCN33_CON0_1,
> -		   0, MT6358_VCN33_ANA_CON0, 0x300),
> +	MT6358_LDO("ldo_vcn33", VCN33, vcn33_voltages, vcn33_idx,
> +		   MT6358_LDO_VCN33_CON0_0, 0, MT6358_VCN33_ANA_CON0, 0x300),

Excuse me if I am being daft here, but could you explain how this change
is compatible with existing devicetrees?

Thanks,
Conor.

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