From: Vladimir Oltean Date: Thu, 20 May 2021 13:12:37 +0000 (+0300) Subject: spi: sc18is602: don't consider the chip select byte in sc18is602_check_transfer X-Git-Tag: v5.15~939^2~7 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=bda7db1d952c3ff7c24c11bc295aa72aaeb98451;p=platform%2Fkernel%2Flinux-starfive.git spi: sc18is602: don't consider the chip select byte in sc18is602_check_transfer For each spi_message, the sc18is602 I2C-to-SPI bridge driver checks the length of each spi_transfer against 200 (the size of the chip's internal buffer) minus hw->tlen (the number of bytes transferred so far). The first byte of the transferred data is the Function ID (the SPI slave's chip select) and as per the documentation of the chip: https://www.nxp.com/docs/en/data-sheet/SC18IS602B.pdf the data buffer is up to 200 bytes deep _without_ accounting for the Function ID byte. However, in sc18is602_txrx(), the driver keeps the Function ID as part of the buffer, and increments hw->tlen from 0 to 1. Combined with the check in sc18is602_check_transfer, this prevents us from issuing a transfer that has exactly 200 bytes in size, but only 199. Adjust the check function to reflect that the Function ID is not part of the 200 byte deep data buffer. Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20210520131238.2903024-2-olteanv@gmail.com Signed-off-by: Mark Brown --- diff --git a/drivers/spi/spi-sc18is602.c b/drivers/spi/spi-sc18is602.c index 297c512..37871ed 100644 --- a/drivers/spi/spi-sc18is602.c +++ b/drivers/spi/spi-sc18is602.c @@ -174,7 +174,7 @@ static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode) static int sc18is602_check_transfer(struct spi_device *spi, struct spi_transfer *t, int tlen) { - if (t && t->len + tlen > SC18IS602_BUFSIZ) + if (t && t->len + tlen > SC18IS602_BUFSIZ + 1) return -EINVAL; return 0;