On Fri Sep 6, 2024 at 5:46 PM EEST, Stefan Wahren wrote:
> 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@xxxxxxx>
> >> ---
> >> 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.
What problem has this patch solved for you? I think it makes the code
only less robust and more error prone.
BR, Jarkko
