From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v3 1/2] tpm_tis_spi: Use DMA-safe memory for SPI transfers Date: Fri, 25 Aug 2017 19:39:19 +0300 Message-ID: <20170825163919.e3v5ph6qlgtquo6r@linux.intel.com> References: <20170824082745.9372-1-Alexander.Steffen@infineon.com> <20170824082745.9372-2-Alexander.Steffen@infineon.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170824082745.9372-2-Alexander.Steffen@infineon.com> Sender: stable-owner@vger.kernel.org To: Alexander Steffen Cc: tpmdd-devel@lists.sourceforge.net, stable@vger.kernel.org List-Id: tpmdd-devel@lists.sourceforge.net On Thu, Aug 24, 2017 at 10:27:44AM +0200, Alexander Steffen wrote: > The buffers used as tx_buf/rx_buf in a SPI transfer need to be DMA-safe. > This cannot be guaranteed for the buffers passed to tpm_tis_spi_read_bytes > and tpm_tis_spi_write_bytes. Therefore, we need to use our own DMA-safe > buffer and copy the data to/from it. > > The buffer needs to be allocated separately, to ensure that it is > cacheline-aligned and not shared with other data, so that DMA can work > correctly. > > Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy") > Cc: stable@vger.kernel.org > Signed-off-by: Alexander Steffen > --- > drivers/char/tpm/tpm_tis_spi.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c > index 88fe72a..05ce841 100644 > --- a/drivers/char/tpm/tpm_tis_spi.c > +++ b/drivers/char/tpm/tpm_tis_spi.c > @@ -47,8 +47,8 @@ struct tpm_tis_spi_phy { > struct tpm_tis_data priv; > struct spi_device *spi_device; > > - u8 tx_buf[4]; > - u8 rx_buf[4]; > + u8 *tx_buf; > + u8 *rx_buf; > }; > > static inline struct tpm_tis_spi_phy *to_tpm_tis_spi_phy(struct tpm_tis_data *data) > @@ -115,10 +115,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len, > > if (direction) { > spi_xfer.tx_buf = NULL; > - spi_xfer.rx_buf = buffer; > } else { > - spi_xfer.tx_buf = buffer; > spi_xfer.rx_buf = NULL; > + memcpy(phy->tx_buf, buffer, transfer_len); > } > > spi_message_init(&m); > @@ -127,6 +126,9 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len, > if (ret < 0) > goto exit; > > + if (direction) > + memcpy(buffer, phy->rx_buf, transfer_len); > + > len -= transfer_len; > buffer += transfer_len; > } > @@ -194,6 +196,14 @@ static int tpm_tis_spi_probe(struct spi_device *dev) > > phy->spi_device = dev; > > + phy->tx_buf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL); > + if (!phy->tx_buf) > + return -ENOMEM; > + > + phy->rx_buf = devm_kmalloc(&dev->dev, MAX_SPI_FRAMESIZE, GFP_KERNEL); > + if (!phy->rx_buf) > + return -ENOMEM; > + > return tpm_tis_core_init(&dev->dev, &phy->priv, -1, &tpm_spi_phy_ops, > NULL); > } > -- > 2.7.4 > Great. This is much less confusing patch for backporting. Reviewed-by: Jarkko Sakkinen /Jarkko