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SubjectRE: [PATCH net-next V3 1/3] dt-bindings: net: xilinx_axienet: Introduce dmaengine binding support
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> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Wednesday, May 17, 2023 8:19 PM
> To: Gaddam, Sarath Babu Naidu
> <sarath.babu.naidu.gaddam@amd.com>; davem@davemloft.net;
> edumazet@google.com; kuba@kernel.org; pabeni@redhat.com;
> robh+dt@kernel.org; krzysztof.kozlowski+dt@linaro.org
> Cc: linux@armlinux.org.uk; Simek, Michal <michal.simek@amd.com>;
> Pandey, Radhey Shyam <radhey.shyam.pandey@amd.com>;
> netdev@vger.kernel.org; devicetree@vger.kernel.org; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Sarangi,
> Anirudha <anirudha.sarangi@amd.com>; Katakam, Harini
> <harini.katakam@amd.com>; git (AMD-Xilinx) <git@amd.com>
> Subject: Re: [PATCH net-next V3 1/3] dt-bindings: net: xilinx_axienet:
> Introduce dmaengine binding support
>
> On 17/05/2023 14:06, Gaddam, Sarath Babu Naidu wrote:
> >>>>> + dma-names:
> >>>>> + items:
> >>>>> + - const: tx_chan0
> >>>>
> >>>> tx
> >>>>
> >>>>> + - const: rx_chan0
> >>>>
> >>>> rx
> >>>
> >>> We want to support more channels in the future, currently we
> support
> >>> AXI DMA which has only one tx and rx channel. In future we want to
> >>> extend support for multichannel DMA (MCDMA) which has 16 TX and
> >>> 16 RX channels. To uniquely identify each channel, we are using chan
> >>> suffix. Depending on the usecase AXI ethernet driver can request any
> >>> combination of multichannel DMA channels.
> >>>
> >>> dma-names = tx_chan0, tx_chan1, rx_chan0, rx_chan1;
> >>>
> >>> will update the commit message with same.
> >>
> >> I expect the binding to be complete, otherwise you get comments like
> this.
> >> Add missing parts to the binding and resend.
> >
> > Binding is complete for current supported DMA (single channel). We
> > will extend when we add MCDMA.
>
> What doe sit mean "current supported DMA"? By driver? or by hardware?
> If the former, then how does it matter for the bindings?
>
> If the latter, then your hardware is going to change? Then you will have
> different set of compatibles and then can use different names.
>
> >
> > We will describe the reason for using channel suffix in the
> > description as below.
> >
> > dma-names:
> > items:
> > - const: tx_chan0
> > - const: rx_chan0
> > description: |
> > Chan suffix is used for identifying each channel uniquely.
> > Current DMA has only one Tx and Rx channel but it will be
> > extended to support for multichannel DMA (MCDMA) which
> > has 16 TX and 16 RX channels. Depending on the usecase AXI
> > ethernet driver can request any combination of multichannel
> > DMA channels.
>
> No, because I don't understand what is "will be extended". Bindings
> should be complete. If they are going to be extended, it means they are
> not complete. If they cannot be complete, which happens, please provide
> a reason. There was no reason so far, except your claim it is complete.

We will re-spin another series with complete bindings including MCDMA
support.

Thanks,
Sarath

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