Am 17. Februar 2017 06:09:30 MEZ schrieb Christophe Ricard <[email protected]>: >That's is correct, this is a mistake on my side and never saw it :-(. > >I guess it was possibly leading to "waste" at least 1 wait state on >some >TPMs.
Unfortunately the 1 for indicating end of waitstates does only appear once so it actually rendered the driver non-functional - atleast with our tpms. > >Wouldn't it be better to merge that with #1 and update the comment >consequently? Yes, that's what I wanted to express in the cover letter, logically it makes sense to squash #1 and #3 - but reviewing it merged with #1 is quite hard since it "obfuscates" the problem - since too much stuff moves around. That's why I decided to split it - for easier review. Peter > > >On 16/02/2017 08:08, Peter Huewe wrote: >> Wait states are signaled in the last byte received from the TPM in >> response to the header, not the first byte. Check rx_buf[3] instead >of >> rx_buf[0]. >> >> Cc: <[email protected]> >> Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy") >> Signed-off-by: Alexander Steffen <[email protected]> >> Signed-off-by: Peter Huewe <[email protected]> >> --- >> drivers/char/tpm/tpm_tis_spi.c | 40 >+++++++++++++++++++++------------------- >> 1 file changed, 21 insertions(+), 19 deletions(-) >> >> diff --git a/drivers/char/tpm/tpm_tis_spi.c >b/drivers/char/tpm/tpm_tis_spi.c >> index d782b9974c14..16938e2253d2 100644 >> --- a/drivers/char/tpm/tpm_tis_spi.c >> +++ b/drivers/char/tpm/tpm_tis_spi.c >> @@ -60,7 +60,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data >*data, u32 addr, u8 len, >> u8 *buffer, u8 direction) >> { >> struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data); >> - int ret, i; >> + int ret; >> struct spi_message m; >> struct spi_transfer spi_xfer = { >> .tx_buf = phy->tx_buf, >> @@ -85,25 +85,27 @@ static int tpm_tis_spi_transfer(struct >tpm_tis_data *data, u32 addr, u8 len, >> if (ret < 0) >> goto exit; >> >> - phy->tx_buf[0] = 0; >> - >> - /* According to TCG PTP specification, if there is no TPM present >at >> - * all, then the design has a weak pull-up on MISO. If a TPM is not >> - * present, a pull-up on MISO means that the SB controller sees a >1, >> - * and will latch in 0xFF on the read. >> - */ >> - for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) { >> - spi_xfer.len = 1; >> - spi_message_init(&m); >> - spi_message_add_tail(&spi_xfer, &m); >> - ret = spi_sync_locked(phy->spi_device, &m); >> - if (ret < 0) >> + if ((phy->rx_buf[3] & 0x01) == 0) { >> + // handle SPI wait states >> + int i; >> + >> + phy->tx_buf[0] = 0; >> + >> + for (i = 0; i < TPM_RETRY; i++) { >> + spi_xfer.len = 1; >> + spi_message_init(&m); >> + spi_message_add_tail(&spi_xfer, &m); >> + ret = spi_sync_locked(phy->spi_device, &m); >> + if (ret < 0) >> + goto exit; >> + if (phy->rx_buf[0] & 0x01) >> + break; >> + } >> + >> + if (i == TPM_RETRY) { >> + ret = -ETIMEDOUT; >> goto exit; >> - } >> - >> - if (i == TPM_RETRY) { >> - ret = -ETIMEDOUT; >> - goto exit; >> + } >> } >> >> spi_xfer.cs_change = 0; -- Sent from my mobile ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/tpmdd-devel
