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definitions=2026-10-14_01,2026-10-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1011 impostorscore=0 adultscore=0 malwarescore=0 suspectscore=0 phishscore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610150055 On Fri, Oct 02, 2026 at 04:55:40PM +0800, Carlos Jones wrote: > From: Carlos Jones Jr > > The driver provides its own transfer_one_message() and therefore drives > the chip-select GPIO itself rather than through the SPI core. The GPIO is > asserted only in the is_first_of_msg path of > tegra_spi_setup_transfer_one(), but tegra_spi_transfer_end() deasserts it > whenever a transfer has cs_change set. For a multi-transfer message whose > earlier transfers request cs_change -- for example a register read that > sends the address in one transfer and clocks the data back in the next -- > the CS GPIO is released after the first transfer and never re-asserted, > so the remaining transfers are clocked with chip-select inactive and the > peripheral never drives the bus. > > This was observed with an ADIS16470 IMU (adis16475 driver), whose > register read is a two-transfer, cs_change-framed exchange: a logic > analyzer showed the data frame clocked with CS high, and the driver read > 0 while the device drove 0x4056 on the wire. > > Re-assert the CS GPIO for every transfer so that multi-transfer messages > keep chip-select active across the whole message. gpiod_set_value() is > idempotent and polarity-aware, so this is a no-op for the first transfer > and for messages that keep CS asserted throughout. > > Fixes: 63c1440596ff ("spi: tegra114: add support for gpio based CS") > Signed-off-by: Carlos Jones Jr > --- > drivers/spi/spi-tegra114.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/spi/spi-tegra114.c b/drivers/spi/spi-tegra114.c > index 1234567..89abcde 100644 > --- a/drivers/spi/spi-tegra114.c > +++ b/drivers/spi/spi-tegra114.c > @@ -859,6 +859,13 @@ static u32 tegra_spi_setup_transfer_one(struct spi_device *spi, > command1 |= SPI_BIT_LENGTH(bits_per_word - 1); > } > > + /* > + * Re-assert the CS GPIO for every transfer: transfer_end() drops it > + * on cs_change, and the assert above only covers is_first_of_msg. > + */ > + if (spi_get_csgpiod(spi, 0)) > + gpiod_set_value(spi_get_csgpiod(spi, 0), 1); > + Makes not much sense to me do do this on top of the `if (is_first_of_msg)` path. I would remove it. Or just set the gpio (if no hw constrain for it) right after: tegra_spi_transfer_end(spi); spi_transfer_delay_exec(xfer); in the `else if (xfer->cs_change)`. We know it's not the last xfer. Would be nice to avoid useless calls to gpiolib. - Nuno Sá > return command1; > } > > -- > 2.43.0