linux-kernel - Re: [PATCH 1/5] dt-bindings: spi: zynqmp-qspi: Add reset

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Message-ID: <20250123224520.GA456390-robh@kernel.org>
Date: Thu, 23 Jan 2025 16:45:20 -0600
From: Rob Herring <robh@...nel.org>
To: Sean Anderson <sean.anderson@...ux.dev>
Cc: Michal Simek <michal.simek@....com>, Mark Brown <broonie@...nel.org>,
	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org,
	Jinjie Ruan <ruanjinjie@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	Amit Kumar Mahapatra <amit.kumar-mahapatra@....com>,
	Miquel Raynal <miquel.raynal@...tlin.com>,
	Conor Dooley <conor+dt@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	devicetree@...r.kernel.org
Subject: Re: [PATCH 1/5] dt-bindings: spi: zynqmp-qspi: Add reset

On Fri, Jan 17, 2025 at 11:12:15AM -0500, Sean Anderson wrote:
> On 1/17/25 02:14, Michal Simek wrote:
> > 
> > 
> > On 1/16/25 23:55, Sean Anderson wrote:
> >> Add a reset to help recover from cancelled operations.
> >>
> >> Signed-off-by: Sean Anderson <sean.anderson@...ux.dev>
> >> ---
> >>
> >>   Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml | 6 ++++++
> >>   1 file changed, 6 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml b/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
> >> index 04d4d3b4916d..901e15fcce2d 100644
> >> --- a/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
> >> +++ b/Documentation/devicetree/bindings/spi/spi-zynqmp-qspi.yaml
> >> @@ -36,12 +36,16 @@ properties:
> >>     power-domains:
> >>       maxItems: 1
> >>   +  resets:
> >> +    maxItems: 1
> >> +
> >>   required:
> >>     - compatible
> >>     - reg
> >>     - interrupts
> >>     - clock-names
> >>     - clocks
> >> +  - resets
> > 
> > In 2/5 you are calling devm_reset_control_get_optional_exclusive() that's why I expect reset is not really required property.
> 
> It's optional for the driver for backwards compatibility. But for the
> devicetree we make it mandatory since it should be included in all new
> devicetrees.

Generally, we discourage new required properties as that's an ABI 
change. The exception is really when optional was a mistake. That's 
arguably the case here if the h/w always has a reset.

Unfortunately, there's not a way to distinguish 'required' from 
'required for new users'.

Rob