From 8980bc573ae2d2b9d86d76aeb86c76e1597070bf Mon Sep 17 00:00:00 2001 From: Carlos Jones Jr Date: Fri, 2 Oct 2026 16:55:40 +0800 Subject: [PATCH] spi: tegra114: assert CS GPIO for every transfer in a message 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 Link: https://patch.msgid.link/20261002085540.1625-1-carlosjr.jones@analog.com Signed-off-by: Mark Brown --- 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 333fb549214e..5f8d8da7a3fc 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); + return command1; }