linux-kernel - Re: [PATCH 5/7] memory: renesas-rpc-if: Move resource acquisition to .probe()

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Date:   Wed, 29 Jun 2022 20:48:28 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Vignesh Raghavendra <vigneshr@...com>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Mark Brown <broonie@...nel.org>,
        MTD Maling List <linux-mtd@...ts.infradead.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/7] memory: renesas-rpc-if: Move resource acquisition to .probe()

Hi Krzysztof,

On Wed, Jun 29, 2022 at 8:26 PM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
> On 29/06/2022 19:55, Geert Uytterhoeven wrote:
> > On Wed, Jun 29, 2022 at 7:44 PM Krzysztof Kozlowski
> > <krzysztof.kozlowski@...aro.org> wrote:
> >> On 27/06/2022 17:31, Geert Uytterhoeven wrote:
> >>> While the acquired resources are tied to the lifetime of the RPC-IF core
> >>> device (through the use of managed resource functions), the actual
> >>> resource acquisition is triggered from the HyperBus and SPI child
> >>> drivers.  Due to this mismatch, unbinding and rebinding the child
> >>> drivers manually fails with -EBUSY:
> >>>
> >>>     # echo rpc-if-hyperflash > /sys/bus/platform/drivers/rpc-if-hyperflash/unbind
> >>>     # echo rpc-if-hyperflash > /sys/bus/platform/drivers/rpc-if-hyperflash/bind
> >>>     rpc-if ee200000.spi: can't request region for resource [mem 0xee200000-0xee2001ff]
> >>>     rpc-if-hyperflash: probe of rpc-if-hyperflash failed with error -16
> >>>
> >>> Fix this by moving all resource acquisition to the core driver's probe
> >>> routine.
> >>>
> >>> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> >>
> >> This looks like a fix, so how about putting it as first in the series,
> >> so backporting is easy/automatic?
> >
> > Unfortunately that is not as simple as it sounds, as this really
> > depends on patch 4.
>
> You sure? Except rebasing I don't see that. rpcif_sw_init() received the
> rpcif so it had access to all fields.

Yes I am, don't be misguided by the name of the local variable.
The rpcif structure is allocated by the HF or SPI child driver,
and thus not available in the RPC core driver's .probe() function.
The rpc_priv structure (as of patch 4) is allocated by the RPC core driver.

> > I agree patches 1-3 could be moved later, if you think it is worthwhile.
>
> This would not be enough, it has to be first patch to be backportable.

I can make it second? ;-)
Note that that still precludes (easily) backporting s2ram support.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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