linux-kernel - Re: [PATCH 07/12] spi: Do spi_take_timestamp

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]

Message-ID: <CA+h21hq8c50AjuzgpxyPQDCFiAdezJuqgY0+u26qBRx9FnYnig@mail.gmail.com>
Date:   Thu, 5 Mar 2020 15:00:22 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-spi@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
        Esben Haabendal <eha@...f.com>, angelo@...am.it,
        andrew.smirnov@...il.com,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Wei Chen <weic@...dia.com>, Mohamed Hosny <mhosny@...dia.com>
Subject: Re: [PATCH 07/12] spi: Do spi_take_timestamp_pre for as many times as necessary

Hi Mark,

On Thu, 5 Mar 2020 at 14:12, Mark Brown <broonie@...nel.org> wrote:
>
> On Thu, Mar 05, 2020 at 12:00:39AM +0200, Vladimir Oltean wrote:
> > From: Vladimir Oltean <vladimir.oltean@....com>
> >
> > When dealing with a SPI controller driver that is sending more than 1
> > byte at once (or the entire buffer at once), and the SPI peripheral
> > driver has requested timestamping for a byte in the middle of the
> > buffer, we find that spi_take_timestamp_pre never records a "pre"
> > timestamp.
>
> This is a fix and so should have been at the start of the series to make
> sure there aren't any dependencies.

My reasoning for not submitting it as a fix is:
- The only driver that uses the functionality so far - spi-fsl-dspi -
has worked thus far even with the limitation that only byte-by-byte
transfers were supported properly.
- I removed the limitation before actually changing the operating mode
of spi-fsl-dspi. Therefore the limitation is effectively never seen.
- New SPI drivers that would want to make use of software timestamping
would do so through your SPI for-next branch anyway, where the
limitation would be, again, fixed.

Thanks,
-Vladimir