Re: [PATCH v7 4/7] board: asus: transformer: add ASUS Transformer T30 family support

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, Jun 23, 2023 at 05:19:09PM +0300, Svyatoslav Ryhel wrote:
> 
> 
> 23 червня 2023 р. 17:11:35 GMT+03:00, Thierry Reding <thierry.reding@gmail.com> написав(-ла):
> >On Fri, Jun 23, 2023 at 02:51:54PM +0300, Svyatoslav Ryhel wrote:
> >> 
> >> 
> >> 23 червня 2023 р. 14:32:30 GMT+03:00, Thierry Reding <thierry.reding@gmail.com> написав(-ла):
> >> >On Fri, Jun 23, 2023 at 08:55:57AM +0300, Svyatoslav Ryhel wrote:
> >> >[...]
> >> >> diff --git a/board/asus/transformer-t30/pinmux-config-transformer.h b/board/asus/transformer-t30/pinmux-config-transformer.h
> >> >> new file mode 100644
> >> >> index 0000000000..96ff45d375
> >> >> --- /dev/null
> >> >> +++ b/board/asus/transformer-t30/pinmux-config-transformer.h
> >> >> @@ -0,0 +1,365 @@
> >> >> +/* SPDX-License-Identifier: GPL-2.0 */
> >> >> +/*
> >> >> + * Copyright (c) 2010-2013, NVIDIA CORPORATION.  All rights reserved.
> >> >> + *
> >> >> + * Copyright (c) 2021, Svyatoslav Ryhel.
> >> >> + */
> >> >
> >> >I don't recall if we discussed this during upstreaming of the Linux
> >> >device tree files, but shortly after the initial support for Tegra20 and
> >> >Tegra30 was upstreamed (both in U-Boot and in Linux) we decided to move
> >> >towards generating the pinmux configuration for the various consumers
> >> >(i.e. U-Boot and Linux) from data tables using a set of scripts. This
> >> >was done because we noticed that various inconsistencies kept creeping
> >> >into the various drivers/tables.
> >> >
> >> >You can find the scripts for this here:
> >> >
> >> >	https://github.com/NVIDIA/tegra-pinmux-scripts
> >> >
> >> >I think there'd be some benefit if these new boards were also converted
> >> >to use these scripts.
> >> 
> >> True, but there is no driver for pinmux which can utilize device tree, instead u-boot relies on board header. I see the benefit of these pinmux nodes only if I can verify that they are correct and do not brake devices. Would be really bad if at some point devices brake cause nodes were not tested.
> >> 
> >> Additionally, shouldn't all supported boards be converted first?
> >
> >The above repository contains a script that will generate the board
> >headers for U-Boot based on a more generic definition of the pinmux
> >configuration. Many devices already have headers that were generated
> >from those scripts, though it's mostly later boards (Tegra124 and
> >onwards).
> >
> >That said, for many of these boards a spreadsheet exists that contains
> >these settings and the tables are generated from that spreadsheet. For
> >many of these OEM devices I suspect no such spreadsheet exists, and it
> >doesn't necessarily make sense to transcribe this into the tables and
> >then convert into board header & DTS snippets. It might be nice to do
> >for consistency, but I'll leave it up to you.
> 
> Current tables are dumped from working vendor kernels. It is not that
> I like this approach, but I would rather leave an existing setup since
> it is well tested and confirmed to be stable enough. No one knows what
> htc and asus did with those pins, at least publicly.

Okay, fair enough.

Thierry

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