linux-kernel - Re: [PATCH 06/14] spi: dt-bindings: dw-apb-ssi: update spi-{r,t}x-bus-width for dwc-ssi

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 21 Jun 2022 12:32:31 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Conor Dooley <mail@...chuod.ie>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Palmer Dabbelt <palmer@...osinc.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Niklas Cassel <niklas.cassel@....com>,
        Dillon Min <dillon.minfei@...il.com>,
        Heng Sia <jee.heng.sia@...el.com>,
        Jose Abreu <joabreu@...opsys.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dmaengine <dmaengine@...r.kernel.org>,
        ALSA Development Mailing List <alsa-devel@...a-project.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH 06/14] spi: dt-bindings: dw-apb-ssi: update
 spi-{r,t}x-bus-width for dwc-ssi

Hi Geert

On Tue, Jun 21, 2022 at 09:03:25AM +0200, Geert Uytterhoeven wrote:
> Hi Serge,
> 
> On Mon, Jun 20, 2022 at 10:56 PM Serge Semin <fancer.lancer@...il.com> wrote:
> > On Sat, Jun 18, 2022 at 01:30:28PM +0100, Conor Dooley wrote:
> > > From: Conor Dooley <conor.dooley@...rochip.com>
> > >

[...]

> > > +
> > > +        spi-rx-bus-width:
> > > +          const: 1
> > > +
> > > +        spi-tx-bus-width:
> > > +          const: 1
> >
> > You can just use a more relaxed constraint "enum: [1 2 4 8]" here
> > irrespective from the compatible string. The modern DW APB SSI
> > controllers of v.4.* and newer also support the enhanced SPI Modes too
> > (Dual, Quad and Octal). Since the IP-core version is auto-detected at
> > run-time there is no way to create a DT-schema correctly constraining
> > the Rx/Tx SPI bus widths. So let's keep the
> > compatible-string-independent "patternProperties" here but just extend
> > the set of acceptable "spi-rx-bus-width" and "spi-tx-bus-width"
> > properties values.
> >

> > Note the DW APB SSI/AHB SSI driver currently doesn't support the
> > enhanced SPI modes. So I am not sure whether the multi-lines Rx/Tx SPI
> > bus indeed works for Canaan K210 AHB SSI controller. AFAICS from the
> > DW APB SSI v4.01a manual the Enhanced SPI mode needs to be properly
> > activated by means of the corresponding CSR. So most likely the DW AHB
> > SSI controllers need some specific setups too.
> 
> That doesn't matter here, as DT describes hardware, not software
> limitations.

Can't argue with that.) My note regarding the current DW APB SSI
driver was mainly addressed for the Canaan K210 users, since
should the SoC-based board really have the Quad Tx/Rx SPI bus
most likely the interface won't work with the full bandwidth.
So it is a good reason to perform the platform research and if
possible alter the driver accordingly.

-Sergey

> 
> 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