From: Jisheng Zhang <jszhang@kernel.org>
Date: Mon, 15 Jun 2026 04:40:35 +0000 (+0800)
Subject: spi: dw: fix first spi transfer with dma always fallback to PIO
X-Git-Tag: v7.2-rc2~6^2~4
X-Git-Url: http://git.ipfire.org/index.cgi?a=commitdiff_plain;h=d322d820e0b0f16260e929de3f4e6b33b242c91c;p=thirdparty%2Flinux.git

spi: dw: fix first spi transfer with dma always fallback to PIO

Even with proper dma engine support, the first spi transfer always
fallback to PIO, the reason is the dws->n_bytes is 0 after
initialization, so the dw_spi_can_dma() calling from __spi_map_msg()
return false, thus both tx_sg_mapped and rx_sg_mapped are false, so
for the first spi transfer, the spi_xfer_is_dma_mapped() reports false
thus fallback to PIO.

Although this brings no harm, we can simply fix this issue by
calcuating the "n_bytes" from xfer->bits_per_word.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://patch.msgid.link/20260615044039.9750-2-jszhang@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
---

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index fe726b9b1780..bd70a7ed8067 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -247,11 +247,12 @@ static bool dw_spi_can_dma(struct spi_controller *ctlr,
 {
 	struct dw_spi *dws = spi_controller_get_devdata(ctlr);
 	enum dma_slave_buswidth dma_bus_width;
+	u8 n_bytes = roundup_pow_of_two(BITS_TO_BYTES(xfer->bits_per_word));
 
 	if (xfer->len <= dws->fifo_len)
 		return false;
 
-	dma_bus_width = dw_spi_dma_convert_width(dws->n_bytes);
+	dma_bus_width = dw_spi_dma_convert_width(n_bytes);
 
 	return dws->dma_addr_widths & BIT(dma_bus_width);
 }