Re: [Linux-stm32] [PATCH 07/22] ARM: dts: stm32: Add alternate pinmux for SDMMC2 pins 4-7

From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Marek Vasut <marex@denx.de>,
	Patrice CHOTARD <patrice.chotard@st.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>,
	Patrick DELAUNAY <patrick.delaunay@st.com>,
	"linux-stm32@st-md-mailman.stormreply.com"
	<linux-stm32@st-md-mailman.stormreply.com>
Subject: Re: [Linux-stm32] [PATCH 07/22] ARM: dts: stm32: Add alternate pinmux for SDMMC2 pins 4-7
Date: Mon, 30 Mar 2020 13:37:44 +0200	[thread overview]
Message-ID: <310aa3a3-09ce-42ef-d1ea-b653163d1d72@pengutronix.de> (raw)
In-Reply-To: <fcf49298-a36c-e80e-e62b-1fb9c07f0d6e@denx.de>

Hi Marek,

On 3/30/20 1:22 PM, Marek Vasut wrote:
> On 3/30/20 1:17 PM, Ahmad Fatoum wrote:
>> Hello Patrice,
> 
> Hi,
> 
>> On 3/30/20 1:11 PM, Patrice CHOTARD wrote:
>>> For your information, another submitted patch uses the same pinctrl sdmmc2_d47_pins_b node with different muxing (SDMMC2_D5)
>>>
>>> see https://lore.kernel.org/patchwork/patch/1216452/
>>>
>>> I haven't checked other muxing if there are other conflict.
>>
>> (author of linked patch here)
>>
>> I don't like the central stm32mp15-pinctrl.dtsi. I'd have preferred if each
>> file defined the pinctrl groups it is using.
> 
> I'm not a big fan of that either, because this is gonna be a
> combinatorial explosion of various pinmux options. But if you have each
> board define it's pinmux, it's also gonna become a massive amount of
> duplication (like iMX). So I cannot tell which one is better ...

Mhm. A middle ground could be keeping stm32mp15-pinctrl, but only for the
official ST eval kits as HW designers are expected to copy off those and have
board specifics in the board/SoM device tree?

If it has to be either one or the other, I prefer duplication in the device
tree. When the HW misses pull ups or needs to adjust slew rates, you probably
don't want a new, slightly different, pinctrl group in the stm32mp15-pinctrl.dtsi
for each variant.

So you are left with doctoring around with overrides and /delete-property/,
while just duplicating the node with the correct properties would've been
better for readability IMO.

> So, just apply one patch or the other, let me know what got applied and
> I'll rebase on top of that and resubmit if needed.

Same.

Cheers
Ahmad

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