linux-kernel - Re: [RESEND PATCH 1/2] mfd: da9063: Fix revision handling to correctly select reg tables

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Date:   Mon, 24 Feb 2020 09:56:54 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Cc:     linux-kernel@...r.kernel.org,
        Support Opensource <support.opensource@...semi.com>
Subject: Re: [RESEND PATCH 1/2] mfd: da9063: Fix revision handling to
 correctly select reg tables

On Fri, 24 Jan 2020, Adam Thomson wrote:

> The current implementation performs checking in the i2c_probe()
> function of the variant_code but does this immediately after the
> containing struct has been initialised as all zero. This means the
> check for variant code will always default to using the BB tables
> and will never select AD. The variant code is subsequently set
> by device_init() and later used by the RTC so really it's a little
> fortunate this mismatch works.
> 
> This update creates an initial temporary regmap instantiation to
> simply read the chip and variant/revision information (common to
> all revisions) so that it can subsequently correctly choose the
> proper regmap tables for real initialisation.

IIUC, you have a dependency issue whereby the device type is required
before you can select the correct Regmap configuration.  Is that
correct?

If so, using Regmap for the initial register reads sounds like
over-kill.  What's stopping you simply using raw reads before the
Regmap is instantiated?

> Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
> ---
>  drivers/mfd/da9063-core.c            |  31 -------
>  drivers/mfd/da9063-i2c.c             | 167 +++++++++++++++++++++++++++++++----
>  include/linux/mfd/da9063/registers.h |  15 ++--
>  3 files changed, 160 insertions(+), 53 deletions(-)

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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