From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Alexander Steffen <Alexander.Steffen@infineon.com>
Cc: tpmdd-devel@lists.sourceforge.net, benoit.houyere@st.com,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH RESEND v3 0/2] tpm_tis_spi: Use DMA-safe memory
Date: Sat, 2 Sep 2017 13:54:24 +0300 [thread overview]
Message-ID: <20170902105424.ej67umlzqfgaue7x@linux.intel.com> (raw)
In-Reply-To: <20170831165819.13544-1-Alexander.Steffen@infineon.com>
On Thu, Aug 31, 2017 at 06:58:17PM +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
>
Great, I'll try to get means to test this!
/Jarkko
next prev parent reply other threads:[~2017-09-02 10:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 16:58 [PATCH RESEND v3 0/2] tpm_tis_spi: Use DMA-safe memory Alexander Steffen
2017-08-31 16:58 ` [PATCH RESEND v3 1/2] tpm_tis_spi: Use DMA-safe memory for SPI transfers Alexander Steffen
2017-08-31 16:58 ` [PATCH RESEND v3 2/2] tpm_tis_spi: Use a single buffer " Alexander Steffen
2017-09-02 10:54 ` Jarkko Sakkinen [this message]
2017-09-06 12:54 ` [PATCH RESEND v3 0/2] tpm_tis_spi: Use DMA-safe memory Jarkko Sakkinen
2017-09-08 12:11 ` Jarkko Sakkinen
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