Re: [PATCH v2 3/4] ASoC: dt-bindings: fsl-sai: allow only one dma-names

From: Conor Dooley <conor@kernel.org>
To: Frank Li <Frank.li@nxp.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Fabio Estevam <festevam@gmail.com>,
	Shengjiu Wang <shengjiu.wang@nxp.com>,
	linux-sound@vger.kernel.org, devicetree@vger.kernel.org,
	imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/4] ASoC: dt-bindings: fsl-sai: allow only one dma-names
Date: Fri, 1 Mar 2024 16:05:25 +0000	[thread overview]
Message-ID: <20240301-crudeness-resale-3c0a1228850d@spud> (raw)
In-Reply-To: <ZeDdMJlxBL4SGkws@lizhi-Precision-Tower-5810>

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On Thu, Feb 29, 2024 at 02:38:24PM -0500, Frank Li wrote:
> On Thu, Feb 29, 2024 at 06:57:29PM +0000, Conor Dooley wrote:
> > On Thu, Feb 29, 2024 at 06:55:58PM +0000, Conor Dooley wrote:
> > > On Tue, Feb 27, 2024 at 03:54:11PM -0500, Frank Li wrote:
> > > > Some sai only connect one direction. So allow only "rx" or "tx" for
> > > > dma-names.
> > > 
> > > Which sai? Can you restrict this per compatible please, so that someone
> > > cannot add 2 dmas for ones where only the tx is supported.
> > > 
> > > |  dmas:
> > > |    minItems: 1
> > > |    items:
> > > |      - description: DMA controller phandle and request line for RX
> > > |      - description: DMA controller phandle and request line for TX
> > > 
> > > The binding already allows only one, but it documents that the first dma
> > > is always the RX dma, and that doesn't change with this patch..
> > 
> > I said "doesn't change" - but I don't think you can change this
> > trivially, as something could rely on the first dma being the rx one.
> > You'd have to check that there is nothing using these using indices
> > rather than names before making any changes here.
> 
> Linux driver and dts with tx only work well. Only issue is dtb_check will
> report error. I want to eliminate these DTB_CHECK warning.

Linux is not the only user of these bindings, citing linux as your
evidence here is only sufficient if no other users exist. Do they?

> And it also reasonable, only rx or tx for a special SAI.
> 
> Can we remove 'description'? dmas should already descripted at common place
> and 'RX' and 'TX' are listed at 'dma-names'

Removing the description has the same problem. The existing binding has
set a fixed order that you now want to make flexible.

Thanks,
Conor.

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