tpmdd-devel.lists.sourceforge.net archive mirror
 help / color / mirror / Atom feed
From: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: Alexander Steffen
	<Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org>
Cc: tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: [PATCH v3 0/2] tpm_tis_spi: Use DMA-safe memory
Date: Sat, 26 Aug 2017 14:22:59 +0300	[thread overview]
Message-ID: <20170826112259.ypwtqbwakyfdqkzo@linux.intel.com> (raw)
In-Reply-To: <20170824082745.9372-1-Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org>

On Thu, Aug 24, 2017 at 10:27:43AM +0200, Alexander Steffen wrote:
> The documentation says that DMA-safe memory is required for SPI transfers.
> The I/O buffers passed in by the caller can be allocated anywhere,
> including on the stack, which is not DMA-safe. So the data needs to be
> copied to separate, DMA-safe buffers.
> 
> We did not see any DMA-related issues on our test systems, even without
> DMA-safe buffers. But this might simply be due to the fact that the SPI
> transfer size is rather small, so our systems do not bother to set up DMA
> transfers. Other systems might do so.
> 
> v2:
> - Updated commit message with more explanations.
> 
> v3:
> - Split into two patches, one for making the buffers DMA-safe and another
>   for using only a single buffer.
> 
> Alexander Steffen (2):
>   tpm_tis_spi: Use DMA-safe memory for SPI transfers
>   tpm_tis_spi: Use a single buffer for SPI transfers
> 
>  drivers/char/tpm/tpm_tis_spi.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
> 
> -- 
> 2.7.4
> 

Needs to be CC linux-kernel and linux-security-module and tested-by.

/Jarkko

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot

  parent reply	other threads:[~2017-08-26 11:22 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-24  8:27 Alexander Steffen
     [not found] ` <20170824082745.9372-1-Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org>
2017-08-24  8:27   ` [PATCH v3 1/2] tpm_tis_spi: Use DMA-safe memory for SPI transfers Alexander Steffen
2017-08-25 16:39     ` Jarkko Sakkinen
2017-08-24  8:27   ` [PATCH v3 2/2] tpm_tis_spi: Use a single buffer " Alexander Steffen
     [not found]     ` <20170824082745.9372-3-Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org>
2017-08-25 16:39       ` Jarkko Sakkinen
2017-08-26 11:22   ` Jarkko Sakkinen [this message]
     [not found]     ` <20170826112259.ypwtqbwakyfdqkzo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-29 12:14       ` [PATCH v3 0/2] tpm_tis_spi: Use DMA-safe memory Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w
     [not found]         ` <9aea582eccbe4655b5de487dacf7c745-nFblLGNE8XKJSz+rYg/bSJowlv4uC7bZ@public.gmane.org>
2017-08-30  8:42           ` Benoit HOUYERE
     [not found]             ` <fe81962beaec4c6fa21ea90df0f01560-tklXXlf0F76qZDvoWP1BVkEOCMrvLtNR@public.gmane.org>
2017-08-31 12:34               ` Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w
2017-08-30 10:08           ` Jarkko Sakkinen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170826112259.ypwtqbwakyfdqkzo@linux.intel.com \
    --to=jarkko.sakkinen-vuqaysv1563yd54fqh9/ca@public.gmane.org \
    --cc=Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org \
    --cc=tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org \
    --subject='Re: [PATCH v3 0/2] tpm_tis_spi: Use DMA-safe memory' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).