From 095858324f063dba830041f067872f0a08765d2f Mon Sep 17 00:00:00 2001 From: Hao-Qun Huang Date: Sun, 13 Sep 2026 03:20:49 +0800 Subject: [PATCH] spi: virtio: Use the per-transfer bits per word virtio_spi_transfer_one() puts spi->bits_per_word into the request header, so a transfer that sets its own word size reaches the backend with the device default instead. The SPI core has already copied that default into xfer->bits_per_word when the transfer leaves it at zero, the same way it does for xfer->speed_hz, which this function already uses. Per-transfer word sizes are ordinary SPI usage. mipi_dbi, for one, sends a 9-bit command and reads the reply as 8-bit data in the same message. With a 16-bit device default, a one-byte transfer asking for 8 bits goes out as a partial 16-bit word, which the backend may reject. Fixes: f98cabe3f6cf ("SPI: Add virtio SPI driver") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hao-Qun Huang Link: https://patch.msgid.link/20260913032049.11209.alvinhuang0603@gmail.com Signed-off-by: Mark Brown --- drivers/spi/spi-virtio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-virtio.c b/drivers/spi/spi-virtio.c index 2256dfec5407..3e181bd8bc94 100644 --- a/drivers/spi/spi-virtio.c +++ b/drivers/spi/spi-virtio.c @@ -168,7 +168,7 @@ static int virtio_spi_transfer_one(struct spi_controller *ctrl, /* Fill struct spi_transfer_head */ th->chip_select_id = spi_get_chipselect(spi, 0); - th->bits_per_word = spi->bits_per_word; + th->bits_per_word = xfer->bits_per_word; th->cs_change = xfer->cs_change; th->tx_nbits = xfer->tx_nbits; th->rx_nbits = xfer->rx_nbits;