Re: [PATCH v3 1/8] soc: mediatek: Add PMIC wrapper for MT8135 and MT6397 SoC

Hi, Arnd,

On Fri, 2014-12-05 at 11:13 +0100, Arnd Bergmann wrote:

On Friday 05 December 2014 12:07:52 Flora Fu wrote:

quoted

Add PMIC wrapper of MT8135 to access MT6397 MFD.

Signed-off-by: Flora Fu <flora.fu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

Please explain what a PMIC wrapper is and why you need one for MT8135.
I don't understand the purpose of this code at all. Is this just another
way of accessing the MT6397 when not using i2c or spi like other
PMIC drivers do?

Yes, MT8135 uses a proprietary hardware to communicate with MT6397. 
The hardware is called PMIC Wrapper or PWRAP.
Since it is not standard i2c or spi protocols, a soc related software
driver is implemented to handle access protocols in AP side.

+-----------------+           +---------------+
|                 |           |               |
| Mediatek AP SoC |           |               |
| (ex. MT8135)    |           |    MT6397     |
|                 |           |               |
|      +--------+ | (SPI bus) | +--------+    |
|      |        | |-----------| |        |    |
|      |  PMIC  | |-----------| |  PMIC  |    |
|      | Wrapper| |-----------| | Wrapper|    |
|      |        | |-----------| |        |    |
|      +--------+ |           | +--------+    |
|                 |           |               |
+-----------------+           +---------------+

Thanks,
Flora


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