[PATCH] memory: renesas-rpc-if: Fix IO state based on flash type

[Geert Uytterhoeven]

Hi Miquel,

On Thu, Sep 14, 2023 at 10:59 AM Miquel Raynal
<miquel.raynal at bootlin.com> wrote:
> geert at linux-m68k.org wrote on Thu, 14 Sep 2023 10:34:50 +0200:
> > On Thu, Sep 14, 2023 at 10:08 AM Krzysztof Kozlowski
> > <krzysztof.kozlowski at linaro.org> wrote:
> > > On 30/08/2023 17:18, Biju Das wrote:
> > > >>>                 regmap_update_bits(rpc->regmap, RPCIF_CMNCR, @@ -774,6
> > > >>> +776,12 @@ static int rpcif_probe(struct platform_device *pdev)
> > > >>>                 return ret;
> > > >>>         }
> > > >>>
> > > >>> +       if (rpc->info->type == RPCIF_RZ_G2L &&
> > > >>
> > > >> Wouldn't this apply to non-RZ/G2L systems, too?
> > > >
> > > > It applies, if the device uses the flash[1] or [2] and it needs
> > > > 4-bit tx support.
> > > >
> > > > [1] Figure 20: QUAD INPUT/OUTPUT FAST READ – EBh/ECh
> > > > https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-a/mt25q_qlks_u_512_aba_0.pdf?rev=3e5b2a574f7b4790b6e58dacf4c889b2
> > > >
> > > > [2] section 8.14
> > > >
> > > > https://www.renesas.com/eu/en/document/dst/at25ql128a-datasheet?r=1608586
> > >
> > > Geert,
> > >
> > > Does it answer your comment or do you expect here some changes?
> >
> > Well, now it has been confirmed this applies to non-RZ/G2L systems, too,
> > the check for RPCIF_RZ_G2L should probably be removed.  In upstream,
> > only arch/arm64/boot/dts/renesas/rzg2l{,c}-smarc-som.dtsi have devices
> > that are compatible with "micron,mt25qu512a", but obviously they can
> > appear elsewhere, too.
> >
> > Now, the presence of that compatible value in rzg2l{,c}-smarc-som.dtsi
> > currently causes a dtbs_check warning, as it is not documented.
> > However, there has been some pushback against adding more compatible
> > values, cfr. my patch to add mt25qu512a[1], and Miquel's commit [2].
>
> Just FYI, I sent [2] after an unsuccessful attempt to update that list
> too, see [3]. The idea is: if you don't have anything useful to add,

Oh, I didn't know that.

> just use the generic compatible. If you need specific changes, you can
> add an entry.

The problem is that usually these things are discovered too late,
so the only prudent way is to be proactive, and always add them.
Initially I thought that the different handling on RZ/G2L was due
to a difference in the RPC-IF block.  But now we know it's due to the
type of FLASH attached.

> [3] https://lore.kernel.org/linux-mtd/d816499e-baab-6200-0780-17a8205b252e@linaro.org/
>
> > But the issue Biju is seeing proves there is a need to add these.
> >
> > In addition, I had hoped to gather some feedback or guidance from the
> > hyperbus and/or spi people, as issues w.r.t. pin states will eventually
> > pop up on other systems, too, and thus may need handling in the core,
> > instead of in each individual device driver.  But of course that can
> > be done later, when the need arises.
> >
> > Thanks!
> >
> > [1] "[PATCH] dt-bindings: mtd: jedec,spi-nor: Document support for
> > more MT25QU parts"
> >     https://lore.kernel.org/all/363186079b4269891073f620e3e2353cf7d2559a.1669988238.git.geert+renesas@glider.be
> > [2] 4b0cb4e7ab2f777c ("dt-bindings: mtd: spi-nor: clarify the need for
> > spi-nor compatibles").

-- 
Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds