rockchip: spi: fix off-by-one in chunk size computation

The maximum transfer length (in a single transaction) for the Rockchip
SPI controller is 64Kframes (i.e. 0x10000 frames) of 8bit or 16bit
frames and is encoded as (num_frames - 1) in CTRLR1.  The existing
code subtracted the "minus 1" twice for a maximum transfer length of
0xffff (64K - 1) frames.

While this is not strictly an error (the existing code is correct, but
leads to a bit of head-scrating), fix this off-by-one situation.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

diff --git a/drivers/spi/rk_spi.c b/drivers/spi/rk_spi.c
index 1df497df6327a94adfe3e915a2a94dff76469cec..e7b2df8d02ef904e17abac17da0f2c496fa2eacb 100644 (file)
--- a/drivers/spi/rk_spi.c
+++ b/drivers/spi/rk_spi.c
@@ -356,7 +356,7 @@ static int rockchip_spi_xfer(struct udevice *dev, unsigned int bitlen,
                spi_cs_activate(dev, slave_plat->cs);
 
        while (len > 0) {
-               int todo = min(len, 0xffff);
+               int todo = min(len, 0x10000);
 
                rkspi_enable_chip(regs, false);
                writel(todo - 1, &regs->ctrlr1);