linux-kernel - Re: [PATCH 2/3] drivers: regulator: qcom: add PMS405 SPMI regulator

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Date:   Thu, 2 May 2019 11:33:16 +0900
From:   Mark Brown <broonie@...nel.org>
To:     Jorge Ramirez <jorge.ramirez-ortiz@...aro.org>
Cc:     lgirdwood@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        bjorn.andersson@...aro.org, vinod.koul@...aro.org,
        niklas.cassel@...aro.org, khasim.mohammed@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/3] drivers: regulator: qcom: add PMS405 SPMI regulator

On Mon, Apr 29, 2019 at 02:31:55PM +0200, Jorge Ramirez wrote:
> On 4/27/19 20:21, Mark Brown wrote:

> > Since the point of this change is AFAICT that this regulator only has a
> > single linear range it seems like it should just be able to use the
> > existing generic functions shouldn't it?  

> yes that would have been ideal but it does not seem to be the case for
> this hardware.

> The register that stores the voltage range for all other SPMI regulators
> (SPMI_COMMON_REG_VOLTAGE_RANGE 0x40) is used by something else in the
> HFS430: SPMI_HFS430_REG_VOLTAGE_LB 0x40 stores the voltage level in two
> bytes 0x40 and 0x41;

> This overlap really what is creating the pain: HFS430 cant use 0x40 to
> store the range (even if it is only one)

> so yeah, most of the changes in the patch are working around this fact.

I'm not sure I follow here, sorry - I can see that the driver needs a
custom get/set selector operation but shouldn't it be able to use the
standard list and map operations for linear ranges?

> 
> enum spmi_common_regulator_registers {
> 	SPMI_COMMON_REG_DIG_MAJOR_REV		= 0x01,
> 	SPMI_COMMON_REG_TYPE			= 0x04,
> 	SPMI_COMMON_REG_SUBTYPE			= 0x05,
> 	SPMI_COMMON_REG_VOLTAGE_RANGE		= 0x40, ******
> 	SPMI_COMMON_REG_VOLTAGE_SET		= 0x41,
> 	SPMI_COMMON_REG_MODE			= 0x45,
> 	SPMI_COMMON_REG_ENABLE			= 0x46,
> 	SPMI_COMMON_REG_PULL_DOWN		= 0x48,
> 	SPMI_COMMON_REG_SOFT_START		= 0x4c,
> 	SPMI_COMMON_REG_STEP_CTRL		= 0x61,
> };
> 
> enum spmi_hfs430_registers {
> 	SPMI_HFS430_REG_VOLTAGE_LB		= 0x40, *******
> 	SPMI_HFS430_REG_VOLTAGE_VALID_LB	= 0x42,
> 	SPMI_HFS430_REG_MODE			= 0x45,
> };
> 
> It just needs it's own
> > set/get_voltage_sel() operations.  As far as I can see the main thing
> > the driver is doing with the custom stuff is handling the fact that
> > there's multiple ranges but that's not an issue for this regulator.
> > It's possible I'm missing something there but that was the main thing
> > (and we do have some generic support for multiple linear ranges in the
> > helper code already, can't remember why this driver isn't using that -
> > the ranges overlap IIRC?).
> > 
> > TBH looking at the uses of find_range() I'm not sure they're 100%
> > sensible as they are - the existing _time_sel() is assuming we only need
> > to work out the ramp time between voltages in the same range which is
> > going to have trouble.
> > 
> 

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