Re: [PATCH 2/3] power: supply: cpcap-charger: Allow changing constant charge voltage

[Tony Lindgren <tony@atomide.com>]

* Pavel Machek <pavel@ucw.cz> [190919 09:27]:
> Hi!
> 
> > Let's allow reconfiguring the cpcap-charger max charge voltage and
> > default to 4.2V that should be safe for the known users.
> > 
> > This allows the users to use 4.35V for the extra capacity if really
> > needed at a cost of probably shorter battery life. We check the
> > constant charge voltage limit set by the battery.
> > 
> > Some pieces of the property setting code is based on an earlier patch
> > from Pavel Machek <pavel@ucw.cz> but limited to configuring the charge
> > voltage for now.
> 
> I'm sorry I'm a tiny bit busy at the moment.
> 
> > +const int cpcap_charge_voltage[] = {
> > +	[CPCAP_REG_CRM_VCHRG_3V80] = 3800000,
> > +	[CPCAP_REG_CRM_VCHRG_4V10] = 4100000,
> > +	[CPCAP_REG_CRM_VCHRG_4V12] = 4120000,
> > +	[CPCAP_REG_CRM_VCHRG_4V15] = 4150000,
> > +	[CPCAP_REG_CRM_VCHRG_4V17] = 4170000,
> > +	[CPCAP_REG_CRM_VCHRG_4V20] = 4200000,
> > +	[CPCAP_REG_CRM_VCHRG_4V23] = 4230000,
> > +	[CPCAP_REG_CRM_VCHRG_4V25] = 4250000,
> > +	[CPCAP_REG_CRM_VCHRG_4V27] = 4270000,
> > +	[CPCAP_REG_CRM_VCHRG_4V30] = 4300000,
> > +	[CPCAP_REG_CRM_VCHRG_4V33] = 4330000,
> > +	[CPCAP_REG_CRM_VCHRG_4V35] = 4350000,
> > +	[CPCAP_REG_CRM_VCHRG_4V38] = 4380000,
> > +	[CPCAP_REG_CRM_VCHRG_4V40] = 4400000,
> > +	[CPCAP_REG_CRM_VCHRG_4V42] = 4420000,
> > +	[CPCAP_REG_CRM_VCHRG_4V44] = 4440000,
> > +};
> 
> We really don't need this kind of explicit table, as the values can be
> simply computed. Can I offer this?
> 
> Best regards,
> 								Pavel
> 
> static int voltage_to_register(int microvolt)
> {
> 	int milivolt = microvolt/1000;
> 	int res;
> 
> 	if (milivolt < 4100)
> 		return CPCAP_REG_CRM_VCHRG_3V80;
> 	if (milivolt > 4350)
> 		return -EINVAL;
> 
> 	milivolt = milivolt - (4100 - 250);
> 	res = milivolt / 250;
> 	BUG_ON(res < 1);
> 	BUG_ON(res > 0xb);
> 	return CPCAP_REG_CRM_VCHRG(res);
> }

Well that does not help as we have four different ranges there.
I got something figured out for the new suggested fix I posted.

Regards,

TOny