Messages in this thread | | | Date | Tue, 25 Feb 2020 09:00:20 +0000 | From | Lee Jones <> | Subject | Re: [RESEND PATCH 1/2] mfd: da9063: Fix revision handling to correctly select reg tables |
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On Mon, 24 Feb 2020, Adam Thomson wrote:
> On 24 February 2020 11:27, Lee Jones wrote: > > > On Mon, 24 Feb 2020, Adam Thomson wrote: > > > > > On 24 February 2020 09:57, Lee Jones wrote: > > > > > > > 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? > > > > > > Yep, spot on. > > > > > > > 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? > > > > > > Actually nothing and I did consider this at the start. Nice thing with regmap > > > is it's all tidily contained and provides the page swapping mechanism to access > > > higher page registers like the variant information. Given this is only once at > > > probe time it felt like this was a reasonable solution. However if you're not > > > keen I can update to use raw access instead. > > > > It would be nice to compare the 2 solutions side by side. I can't see > > the raw reads of a few device-ID registers being anywhere near 170 > > lines though. > > To be fair the regmap specific additions for the temporary register access, are > maybe 50 - 60 lines. The rest is to do with handling the result which you'll > need anyway to select the correct register map. I reckon to provide raw read and > write access we're going to probably be similar or more as we'll need to write > the page register then read from the relevant ID registers. Using this an > example for the lines count: > > https://elixir.bootlin.com/linux/latest/source/drivers/mfd/tps6507x.c#L37
Ah, they are I2C transactions? Not the nice readl()s I had in mind.
> I can knock something together though just to see what it looks like.
Well, I'd appreciated that, thanks.
-- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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