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
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next prev 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 [PATCH v3 0/2] tpm_tis_spi: Use DMA-safe memory 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
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