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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: Wed, 6 Sep 2017 15:54:58 +0300	[thread overview]
Message-ID: <20170906125458.ueqpmokh7bg64olc@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
> 

Applied to my bleeding edge master brach for more convenient testing.
Have not yet applied to my next branch.

/Jarkko

  parent reply	other threads:[~2017-09-06 12:54 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-31 16:58 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 ` [PATCH RESEND v3 0/2] tpm_tis_spi: Use DMA-safe memory Jarkko Sakkinen
2017-09-06 12:54 ` Jarkko Sakkinen [this message]
2017-09-08 12:11   ` Jarkko Sakkinen

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