linux-kernel - Re: [RFC] i.MX25/35/SDHCI: switch off DMA usage

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: <201504141142.00237.jbe@pengutronix.de>
Date:	Tue, 14 Apr 2015 11:42:00 +0200
From:	Juergen Borleis <jbe@...gutronix.de>
To:	Dong Aisheng <b29396@...escale.com>
Cc:	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Chris Ball <chris@...ntf.net>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Shawn Guo <shawn.guo@...aro.org>, linux-kernel@...r.kernel.org
Subject: Re: [RFC] i.MX25/35/SDHCI: switch off DMA usage

Hi,

On Friday 27 March 2015 12:44:03 Dong Aisheng wrote:
> On Fri, Mar 27, 2015 at 11:52:04AM +0100, Juergen Borleis wrote:
> > DMA and the required overhead on very small data blocks seems an
> > expensive operation. Due to erratum ENGCM07207 for i.MX25 and i.MX35 SoCs
> > the support for multiblock transfers is disabled which results into a
> > huge amount of single 512 byte sector transfers and interrupts. This
> > slows down the transmission speed to below 500 kiB/s (even at 50 MHz SD
> > card clock). Using PIO instead of DMA to avoid ENGCM07207 happens and
> > re-enabling multiblock transfers again improve the transmission
> > capability up to about 2.5 MiB/s.
> >
> > I'm still not sure if ENGCM07207 is related to DMA only and can not
> > happen when PIO is used instead. Someone out there with experience
> > regarding this topic?
>
> The errata does not state it's related to DMA only.
> http://cache.freescale.com/files/dsp/doc/errata/IMX35CE.pdf
> I could double check with our IC guys to confirm it.

Gentle ping.

Regards,
Juergen

-- 
Pengutronix e.K.                              | Juergen Borleis             |
Industrial Linux Solutions                    | http://www.pengutronix.de/  |
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/