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Message-ID: <e7d402f4-0463-4bb2-b1ea-afb36a58e59a@gmx.net> Date: Fri, 6 Sep 2024 16:46:52 +0200 From: Stefan Wahren <wahrenst@....net> To: Jarkko Sakkinen <jarkko@...nel.org>, Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca> Cc: linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org, Stefan Berger <stefanb@...ux.ibm.com> Subject: Re: [PATCH RFC 1/2] tpm: tpm_tis_spi: Ensure SPI mode 0 Am 06.09.24 um 11:47 schrieb Jarkko Sakkinen: > On Fri Sep 6, 2024 at 9:09 AM EEST, Stefan Wahren wrote: >> According to TCG PC Client Platform TPM Profile (PTP) Specification >> only SPI mode 0 is supported. In order to ensure the SPI controller >> supports the necessary settings, call spi_setup() and bail out >> as soon as possible in error case. >> >> This change should affect all supported TPM SPI devices, because >> tpm_tis_spi_probe is either called direct or indirectly. >> >> Signed-off-by: Stefan Wahren <wahrenst@....net> >> --- >> drivers/char/tpm/tpm_tis_spi_main.c | 11 +++++++++++ >> 1 file changed, 11 insertions(+) >> >> diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c >> index 61b42c83ced8..e62d297b040e 100644 >> --- a/drivers/char/tpm/tpm_tis_spi_main.c >> +++ b/drivers/char/tpm/tpm_tis_spi_main.c >> @@ -248,6 +248,17 @@ static int tpm_tis_spi_write_bytes(struct tpm_tis_data *data, u32 addr, >> int tpm_tis_spi_init(struct spi_device *spi, struct tpm_tis_spi_phy *phy, >> int irq, const struct tpm_tis_phy_ops *phy_ops) >> { >> + int ret; >> + >> + spi->mode &= ~SPI_MODE_X_MASK; >> + spi->mode |= SPI_MODE_0; >> + >> + ret = spi_setup(spi); >> + if (ret < 0) { >> + dev_err(&spi->dev, "SPI setup failed: %d\n", ret); >> + return ret; >> + } >> + >> phy->iobuf = devm_kmalloc(&spi->dev, SPI_HDRSIZE + MAX_SPI_FRAMESIZE, GFP_KERNEL); >> if (!phy->iobuf) >> return -ENOMEM; >> -- >> 2.34.1 > > Why? SPI protocol driver usually call spi_setup to verify that the SPI controller accept the settings (SPI mode, bit, clock rate ...). Bailing out early is more helpful for debugging issues. > > BR, Jarkko
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