From: Avri Altman <Avri.Altman@sandisk.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Ulf Hansson <ulf.hansson@linaro.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
Adrian Hunter <adrian.hunter@intel.com>,
Paolo Valente <paolo.valente@linaro.org>
Subject: RE: Outstanding MQ questions from MMC
Date: Sat, 15 Apr 2017 19:24:55 +0000 [thread overview]
Message-ID: <BY2PR0401MB0901B0167734FEFB7F1E5DF6E5040@BY2PR0401MB0901.namprd04.prod.outlook.com> (raw)
In-Reply-To: <CACRpkdbstMEC-_JcEfEm1debQRPeYBDmTPm0L_jGFnrgRZg1Zw@mail.gmail.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Avri Altman <Avri.Altman@sandisk.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Ulf Hansson <ulf.hansson@linaro.org>,
"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
Adrian Hunter <adrian.hunter@intel.com>,
Paolo Valente <paolo.valente@linaro.org>
Subject: RE: Outstanding MQ questions from MMC
Date: Sat, 15 Apr 2017 19:24:55 +0000 [thread overview]
Message-ID: <BY2PR0401MB0901B0167734FEFB7F1E5DF6E5040@BY2PR0401MB0901.namprd04.prod.outlook.com> (raw)
In-Reply-To: <CACRpkdbstMEC-_JcEfEm1debQRPeYBDmTPm0L_jGFnrgRZg1Zw@mail.gmail.com>
You can see how it's done in mmc_blk_ioctl_rpmb_cmd().
The RPMB protocol defines 6 types of accesses:
Accesses that performs read operation (read counter, read data, and read configuration) - requires sending 2 requests.
Accesses that performs write operation (program key, write data, write configuration) - requires sending 3 requests,
But you must do read counter beforehand (accept from program key), hence the 5 different requests.
The standard does not define a "special" request that does it all in once,
but expects a pre-define series of cmd18 & cmd25 for each access type,
in which the payload are 512 bytes frames in a pre-defined structure.
Cheers,
Avri
> -----Original Message-----
> From: Linus Walleij [mailto:linus.walleij@linaro.org]
> Sent: Saturday, April 15, 2017 9:35 PM
> To: Avri Altman <Avri.Altman@sandisk.com>
> Cc: Arnd Bergmann <arnd@arndb.de>; Ulf Hansson
> <ulf.hansson@linaro.org>; linux-mmc@vger.kernel.org; linux-
> block@vger.kernel.org; Jens Axboe <axboe@kernel.dk>; Christoph Hellwig
> <hch@lst.de>; Adrian Hunter <adrian.hunter@intel.com>; Paolo Valente
> <paolo.valente@linaro.org>
> Subject: Re: Outstanding MQ questions from MMC
>
> On Fri, Apr 14, 2017 at 8:41 PM, Avri Altman <Avri.Altman@sandisk.com>
> wrote:
> > [Me]
> >> 2. Turn RPMB and other ioctl() MMC operations into mmc_queue_req
> >> things and funnel them into the block scheduler
> >> using REQ_OP_DRV_IN/OUT requests.
> >>
> >
> > Accessing the RPMB is done via a strange protocol, in which each access is
> comprised of several requests.
> > For example, writing to the RPMB will require sending 5 different requests:
> > 2 requests to read the write counter, and then 3 more requests for the
> write operation itself.
> >
> > Once the sequence has started, it should not get interfered by other
> requests, or the operation will fail.
>
> So I guess currently something takes a host lock and then performs the
> 5 requests.
>
> Thus we need to send a single custom request containing a list of 5 things to
> do, and return after that.
>
> Or do you mean that we return to userspace inbetween these different
> requests and the sequencing is done in userspace?
>
> I hope not because that sounds fragile, like userspace could crash and leave
> the host lock dangling :/
>
> Yours,
> Linus Walleij
next prev parent reply other threads:[~2017-04-15 19:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 3:09 Outstanding MQ questions from MMC Linus Walleij
2017-03-30 12:42 ` Arnd Bergmann
2017-03-30 16:39 ` Ulf Hansson
2017-03-31 8:43 ` Arnd Bergmann
2017-04-13 13:22 ` Linus Walleij
2017-04-14 18:41 ` Avri Altman
2017-04-14 18:41 ` Avri Altman
2017-04-15 18:34 ` Linus Walleij
2017-04-15 19:24 ` Avri Altman [this message]
2017-04-15 19:24 ` Avri Altman
2017-04-18 15:31 ` Alex Lemberg
2017-04-18 15:31 ` Alex Lemberg
2017-05-18 9:36 ` Linus Walleij
2017-04-15 10:20 ` Ulf Hansson
2017-05-18 9:40 ` Christoph Hellwig
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