linux-kernel - Re: regulator: pfuze100: A few small questions

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Message-ID: <20130730022603.GA1430@Robin-OptiPlex-780>
Date:	Tue, 30 Jul 2013 10:26:04 +0800
From:	Robin Gong <b38343@...escale.com>
To:	Axel Lin <axel.lin@...ics.com>
CC:	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: regulator: pfuze100: A few small questions

On Mon, Jul 29, 2013 at 11:44:40PM +0800, Axel Lin wrote:
> >> Current code adjust min_uV and uV_step when SW2~SW4 high bit is set.
> >> I'm wondering if n_voltages is correct or not in this case because
> >> the n_voltages is calculated by original equation (max-min/step + 1).
> >> What is the max_uV when SW2~SW4 high bit is set?
> >>
> > If high bit set(bit6, bit0~5:vsel), min_uV/step will change from 0.4V/25mV to
> > 0.8V/50mV,but the n_voltages will kept the same.
> > For example,SW2 will vary from 0.4V to 1.975V(0x0~0x3f),if bit6 set 0(high bit)
> > SW2 will vary from 0.8V to 3.3V(0x40~0x72,0x72~0x7f:reversed).
> > Please ignore bit7 or consider it as 0.
> 
> Hi Robin,
> According to your description:
> BIT6 is clear: 0.4V ~ 1.975V , step 25mV (0x0~0x3f)
> BIT6 is set:   0.8V ~ 3.3V, step 50mV    (0x40~0x72,0x72~0x7f:reversed)
> 
> For SW2/SW3A/SW3B/SW4:
> I think current implementation is wrong.
> The supported voltage range should cover the whole range: 0.4V ~ 3.3V.
> 
Hi Alex, 
Yes,the default setting of SW2 ~SW4in the regulator array is 0.4V~1.975V
(Bit6 clear),and my code will check the true setting of Bit6. If Bit6=1
I will change min_uV from 0.4V to 0.8V ,step from 25mV to 50mV as what
hardware define. I don't think we should mix the two define as what you
mean 0.4V~3.3V. Because for every pfuze100 chip, the voltage of SW2~SW4
is 0.4V~1.975V or 0.8V~3.3V, not 0.4V~3.3V(from software view,Bit6 only
readable).

> You need to implement set_voltage_sel/get_voltage_sel:
> For 0.4V ~ 1.975V, use 25mV step and clear BIT6.
> For 2V ~ 3.3V, use 50mV step and set BIT6
>
No,should be:
For 0.8V~3.3V, use 50mV step if set BIT6
> And use regulator_list_voltage_linear_range / regulator_map_voltage_linear_range
> 
Yes, I have used regulator_list_voltage_linear to list voltage, so that
regulator core will regulator_map_voltage_linear to find the right voltage.
> Below list the register value and voltage mapping:
> 
> reg     volt    (reg with BIT6 is set)
> ================================
> 0x00    400000
> 0x01    425000
> 0x02    450000
> 0x03    475000
> 0x04    500000
> ...     ......
> 0x0e    750000
> 0x0f    775000
> 0x10    800000  (0x40)
> 0x11    825000
> 0x12    850000  (0x41)
> 0x13    875000
> 0x14    900000  (0x42)
> 0x15    925000
> 0x16    950000  (0x43)
> 0x17    975000
> 0x18    1000000 (0x44)
> 0x19    1025000
> 0x1a    1050000 (0x45)
> 0x1b    1075000
> 0x1c    1100000 (0x46)
> 0x1d    1125000
> 0x1e    1150000 (0x47)
> 0x1f    1175000
> ...     .......
> 0x3c    1950000 (0x57)
> 0x3f    1975000
>         2000000 (0x58)
>         2050000 (0x59)
>         2100000 (0x5a)
>         .....
>         3300000 (0x72)
>
Great, the voltage mapping is right.
> Regards,
> Axel
> 

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