Messages in this thread | | | Date | Wed, 23 Sep 2009 16:38:15 +0200 | From | Wolfram Sang <> | Subject | Re: [RFC] regulator: add driver for MAX8660/8661 |
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Hi Liam,
> Fwiw, the WM8350 has several similar boot up modes. Luckily we can read > back this device to determine mode and any boot loader config. It may > also be required to add any shadow register changes to your > platform_data. i.e. if boot loader does any writes.
While I thought about how to achieve that (Specify voltages and convert them back to selector-values? Ask for the selector value? Enforce a complete register set?), I concluded that there are lots of details in here, and I'd spare that for the case when it is actually needed. In our case, it is not.
> Btw, have you tried register read back ? The data sheet mentions a > "bidirectional" I2C SDA line implying the device registers can be read > back, even though they are all marked W in the register map.
The line itself has the capability of being bidirectional, still the chips has no logic for being read. Page 37 states:
"The MAX8660/MAX8661 are write-only devices and recognize the 'write byte' protocol as defined in the SMBus specification and shown in section A of Figure 11..."
And to be very sure, I just tried a read -> '-EIO'
> > > +The Target Voltage 2 Registers for V3, V4 and V5 are not used by this driver. > > + > > +Note that disabling V3 or V4 has no effect if pin EN34 is driven high (pin and > > +register are ORed, see datasheet). > > + > > Sounds like EN34 status should be in platform_data.
Good idea, will implement that.
Regards,
Wolfram
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