linux-kernel - Re: [PATCH net-next v10 6/6] net: dt-bindings: dwmac: add support for mt8195

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Message-ID: <14636842a61bb7631584315901bcc06ccbdb0f90.camel@mediatek.com>
Date:   Fri, 14 Jan 2022 13:38:24 +0800
From:   Biao Huang <biao.huang@...iatek.com>
To:     Rob Herring <robh@...nel.org>
CC:     srv_heupstream <srv_heupstream@...iatek.com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        David Miller <davem@...emloft.net>,
        "moderated list:ARM/STM32 ARCHITECTURE" 
        <linux-stm32@...md-mailman.stormreply.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        netdev <netdev@...r.kernel.org>, <dkirjanov@...e.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Macpaul Lin <macpaul.lin@...iatek.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        <devicetree@...r.kernel.org>, Jakub Kicinski <kuba@...nel.org>
Subject: Re: [PATCH net-next v10 6/6] net: dt-bindings: dwmac: add support
 for mt8195

On Tue, 2022-01-11 at 17:36 -0600, Rob Herring wrote:
> On Thu, Dec 16, 2021 at 8:06 PM Biao Huang <biao.huang@...iatek.com>
> wrote:
> > 
> > Dear Rob,
> >   Thanks for your comments~
> > 
> >   For mt8195, the eth device node will look like:
> >   eth: ethernet@...21000 {
> >     compatible = "mediatek,mt8195-gmac", "snps,dwmac-5.10a";
> >     ...
> >     clock-names = "axi",
> >                   "apb",
> >                   "mac_cg",
> >                   "mac_main",
> >                   "ptp_ref",
> >                   "rmii_internal";
> >     clocks = <&pericfg_ao CLK_PERI_AO_ETHERNET>,
> >              <&pericfg_ao CLK_PERI_AO_ETHERNET_BUS>,
> >              <&pericfg_ao CLK_PERI_AO_ETHERNET_MAC>,
> >              <&topckgen CLK_TOP_SNPS_ETH_250M>,
> >              <&topckgen CLK_TOP_SNPS_ETH_62P4M_PTP>,
> >              <&topckgen CLK_TOP_SNPS_ETH_50M_RMII>;
> >     ...
> >   }
> > 
> > 1. "rmii_internal" is a special clock only required for
> >    RMII phy interface, dwmac-mediatek.c will enable clocks
> >    invoking clk_bulk_prepare_enable(xx, 6) for RMII,
> >    and clk_bulk_prepare_enable(xx, 5) for other phy interfaces.
> >    so, mt2712/mt8195 all put "rmii_internal" clock to the
> >    end of clock list to simplify clock handling.
> > 
> >    If I put mac_cg as described above, a if condition is required
> > for clocks description in dt-binding, just like what I do in v7
> > send:
> >   - if:
> >       properties:
> >         compatible:
> >           contains:
> >             enum:
> >               - mediatek,mt2712-gmac
> > 
> >     then:
> >       properties:
> >         clocks:
> >           minItems: 5
> >           items:
> >             - description: AXI clock
> >             - description: APB clock
> >             - description: MAC Main clock
> >             - description: PTP clock
> >             - description: RMII reference clock provided by MAC
> > 
> >         clock-names:
> >           minItems: 5
> >           items:
> >             - const: axi
> >             - const: apb
> >             - const: mac_main
> >             - const: ptp_ref
> >             - const: rmii_internal
> > 
> >   - if:
> >       properties:
> >         compatible:
> >           contains:
> >             enum:
> >               - mediatek,mt8195-gmac
> > 
> >     then:
> >       properties:
> >         clocks:
> >           minItems: 6
> >           items:
> >             - description: AXI clock
> >             - description: APB clock
> >             - description: MAC clock gate
> >             - description: MAC Main clock
> >             - description: PTP clock
> >             - description: RMII reference clock provided by MAC
> > 
> >    This introduces some duplicated description.
> > 
> > 2. If I put "mac_cg" to the end of clock list,
> >    the dt-binding file can be simple just like
> >    what we do in this v10 patch(need fix warnings reported by "make
> > DT_CHECKER_FLAGS=-m dt_binding_check").
> > 
> >    But for mt8195:
> >      the eth node in dts should be modified,
> 
> I hope you are defining the binding before you use it... That's not
> good practice and not a valid argument.
> 
> >      and eth driver clock handling will be complex;
> 
> How so?
> 
> Rob
OK, I'll add a driver patch to make clock setting more reasonable,
and modify this patch as previous comments.

Thanks for your comments~