linux-kernel - Re: [PATCH 6/6] memory: renesas-rpc-if: Add support for RZ/G2L

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Message-ID: <CA+V-a8sDSsyTGfTeQfG_ZhfrJHCm+2kBTEDWaoFMTgsMOmxEgQ@mail.gmail.com>
Date:   Fri, 1 Oct 2021 09:02:06 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Rob Herring <robh+dt@...nel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Vignesh Raghavendra <vigneshr@...com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Mark Brown <broonie@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sergei Shtylyov <sergei.shtylyov@...il.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, linux-mtd@...ts.infradead.org,
        linux-spi <linux-spi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Prabhakar <prabhakar.csengg@...il.com>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH 6/6] memory: renesas-rpc-if: Add support for RZ/G2L

Hi Wolfram,

Thank you for the review.

On Thu, Sep 30, 2021 at 3:40 PM Wolfram Sang
<wsa+renesas@...g-engineering.com> wrote:
>
> Hi,
>
> >  #define RPCIF_CMNCR_IO3FV(val)       (((val) & 0x3) << 14) /* undocumented */
> >  #define RPCIF_CMNCR_IO2FV(val)       (((val) & 0x3) << 12) /* undocumented */
> >  #define RPCIF_CMNCR_IO0FV(val)       (((val) & 0x3) << 8)
> > -#define RPCIF_CMNCR_IOFV_HIZ (RPCIF_CMNCR_IO0FV(3) | RPCIF_CMNCR_IO2FV(3) | \
> > -                              RPCIF_CMNCR_IO3FV(3))
> > +#define RPCIF_CMNCR_IOFV_HIZ(val) (RPCIF_CMNCR_IO0FV(val) | RPCIF_CMNCR_IO2FV(val) | \
> > +                              RPCIF_CMNCR_IO3FV(val))
>
> Is RPCIF_CMNCR_IO3FV and RPCIF_CMNCR_IO2FV actually documented in your
> datasheets? I am asking because I have a patch pending to remove writing
> to undocumented locations. So, I was aboout to remove the IO3FV and
> IO2FV macros.
>
Yes they are documented, you should be able to download the HW manual from [1]

> > +#define RPCIF_PHYADJ1                0x0070  /* R/W */
> > +#define RPCIF_PHYADJ2                0x0074  /* R/W */
>
> Those are named 'PHYADD' and 'PHYWR' in the Gen3 documentation. They are
> only available on a few of the Gen3 SoCs. I think the Gen3 namings make
> more sense because then it becomes easily understandable that the
> registers are used to write something to the PHY.
>
Agreed, will re-name it as per Gen3.

> > +#define RPCIF_PHYCNT_CKSEL(v)        (((v) & 0x3) << 16)
>
> We should add a comment here that these bits are only valid for G2L...
>
Will do.

> >  #define RPCIF_PHYCNT_STRTIM(v)       (((v) & 0x7) << 15)
>
> and these only for Gen3.
>
ditto.

>
> > +static void rpcif_timing_adjust_sdr(struct rpcif *rpc)
> > +{
> > +     u32 data;
> > +
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ2, 0xA5390000);
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ1, 0x80000000);
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ2, 0x00008080);
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ1, 0x80000022);
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ2, 0x00008080);
> > +     regmap_write(rpc->regmap, RPCIF_PHYADJ1, 0x80000024);
>
> Can't we have defines for these magic values? At least in my latest Gen3
> documentation, these values are explained.
>
RZ/G2L manual doesn't explain these bits. Let me refer to R-Car Gen3
and define them as macros.

> > +
> > +     regmap_read(rpc->regmap, RPCIF_PHYCNT, &data);
> > +     regmap_write(rpc->regmap, RPCIF_PHYCNT, data | RPCIF_PHYCNT_CKSEL(3));
>
> regmap_update_bits?
>
will do.

> > +     if (rpc->type == RPCIF_RCAR_GEN3) {
> > +             regmap_write(rpc->regmap, RPCIF_PHYCNT, RPCIF_PHYCNT_STRTIM(7) |
> > +                          RPCIF_PHYCNT_PHYMEM(hyperflash ? 3 : 0) | 0x260);
> > +     } else {
> > +             regmap_read(rpc->regmap, RPCIF_PHYCNT, &dummy);
> > +             dummy &= ~RPCIF_PHYCNT_PHYMEM_MASK;
> > +             dummy |= RPCIF_PHYCNT_PHYMEM(hyperflash ? 3 : 0) | 0x260;
> > +             regmap_write(rpc->regmap, RPCIF_PHYCNT, dummy);
>
> regmap_update_bits?
>
Im a bit hesitant to use regmap_update_bits() here as some of the bits
are not documented.

[1] https://www.renesas.com/us/en/products/microcontrollers-microprocessors/rz-arm-based-high-end-32-64-bit-mpus/rzg2l-general-purpose-microprocessors-dual-core-arm-cortex-a55-12-ghz-cpus-3d-graphics-and-video-codec

Cheers,
Prabhakar

> Rest looks good.
>
> Thanks and happy hacking!
>
>    Wolfram
>