netdev - Re: [PATCH net-next v2 09/12] net: stmmac: Add EMAC3 variant of dwmac4

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Message-ID: <20230321221958.e3s7mbpxp5hpm7su@halaney-x13s>
Date:   Tue, 21 Mar 2023 17:19:58 -0500
From:   Andrew Halaney <ahalaney@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     linux-kernel@...r.kernel.org, agross@...nel.org,
        andersson@...nel.org, konrad.dybcio@...aro.org,
        davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        vkoul@...nel.org, bhupesh.sharma@...aro.org,
        mturquette@...libre.com, sboyd@...nel.org, peppe.cavallaro@...com,
        alexandre.torgue@...s.st.com, joabreu@...opsys.com,
        mcoquelin.stm32@...il.com, richardcochran@...il.com,
        linux@...linux.org.uk, veekhee@...le.com,
        tee.min.tan@...ux.intel.com, mohammad.athari.ismail@...el.com,
        jonathanh@...dia.com, ruppala@...dia.com, bmasney@...hat.com,
        andrey.konovalov@...aro.org, linux-arm-msm@...r.kernel.org,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, ncai@...cinc.com,
        jsuraj@....qualcomm.com, hisunil@...cinc.com, echanude@...hat.com
Subject: Re: [PATCH net-next v2 09/12] net: stmmac: Add EMAC3 variant of
 dwmac4

On Mon, Mar 20, 2023 at 08:41:53PM -0700, Jakub Kicinski wrote:
> On Mon, 20 Mar 2023 17:16:14 -0500 Andrew Halaney wrote:
> > The next approach that was checked was to have a function pointer
> > embedded inside a structure that does the appropriate conversion based
> > on the variant that's in use. However, some of the function definitions
> > are like the following:
> > 
> >     void emac3_set_rx_ring_len(void __iomem *ioaddr, u32 len, u32 chan)
> 
> I checked a couple of callbacks and they seem to all be called with
> priv->iomem as an arg, so there is no strong reason to pass iomem
> instead of priv / hw. Or at least not to pass both..
> 
> I think that's a better approach than adding the wrappers :(
> 
> Are you familiar with coccinelle / spatch? It's often better than 
> just regexps for refactoring, maybe it can help?
> 

No worries, I'll try and refactor as you mentioned. Looking at it some
this afternoon makes me think I'll try something like this:

    diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h
    index 16a7421715cb..75c55f696c7a 100644
    --- a/drivers/net/ethernet/stmicro/stmmac/hwif.h
    +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h
    @@ -12,7 +12,7 @@
     ({ \
            int __result = -EINVAL; \
            if ((__priv)->hw->__module && (__priv)->hw->__module->__cname) { \
    -               (__priv)->hw->__module->__cname((__arg0), ##__args); \
    +               (__priv)->hw->__module->__cname((__priv), (__arg0), ##__args); \
                    __result = 0; \
            } \
            __result; \
    @@ -21,7 +21,7 @@
     ({ \
            int __result = -EINVAL; \
            if ((__priv)->hw->__module && (__priv)->hw->__module->__cname) \
    -               __result = (__priv)->hw->__module->__cname((__arg0), ##__args); \
    +               __result = (__priv)->hw->__module->__cname((__priv), (__arg0), ##__args); \
            __result; \
     })
     
    @@ -34,68 +34,68 @@ struct dma_edesc;
     /* Descriptors helpers */
     struct stmmac_desc_ops {
            /* DMA RX descriptor ring initialization */
    -       void (*init_rx_desc)(struct dma_desc *p, int disable_rx_ic, int mode,
    -                       int end, int bfsize);
    +       void (*init_rx_desc)(struct stmmac_priv *priv, struct dma_desc *p,
    +                            int disable_rx_ic, int mode, int end, int bfsize);
            /* DMA TX descriptor ring initialization */
    (...)

and then, I'll add something like:

    diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
    index a152678b82b7..f5f406a09ae3 100644
    --- a/include/linux/stmmac.h
    +++ b/include/linux/stmmac.h
    @@ -273,5 +273,7 @@ struct plat_stmmacenet_data {
            bool use_phy_wol;
            bool sph_disable;
            bool serdes_up_after_phy_linkup;
    +       u32 mtl_base;
    +       u32 mtl_offset;
     };
     #endif

and rewrite:

    #define MTL_CHANX_BASE_ADDR(x)		(MTL_CHAN_BASE_ADDR + \
                                            (x * MTL_CHAN_BASE_OFFSET))

to use mtl_base/offset if they exist, and so on for the DMA versions,
etc...

I'm sure I'll probably run into some issue and change course slightly,
but thought I'd post a hint of the path to make sure I'm not way off the
mark.

Thanks for your feedback,
Andrew