From: Joy Chakraborty Date: Fri, 12 May 2023 10:47:45 +0000 (+0000) Subject: spi: dw: Round of n_bytes to power of 2 X-Git-Tag: v6.1.39~511 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=34d04d70194d19ba9847400c12fcdeae6826630c;p=platform%2Fkernel%2Flinux-starfive.git spi: dw: Round of n_bytes to power of 2 [ Upstream commit 9f34baf67e4d08908fd94ff29c825bb673295336 ] n_bytes variable in the driver represents the number of bytes per word that needs to be sent/copied to fifo. Bits/word can be between 8 and 32 bits from the client but in memory they are a power of 2, same is mentioned in spi.h header: " * @bits_per_word: Data transfers involve one or more words; word sizes * like eight or 12 bits are common. In-memory wordsizes are * powers of two bytes (e.g. 20 bit samples use 32 bits). * This may be changed by the device's driver, or left at the * default (0) indicating protocol words are eight bit bytes. * The spi_transfer.bits_per_word can override this for each transfer. " Hence, round of n_bytes to a power of 2 to avoid values like 3 which would generate unalligned/odd accesses to memory/fifo. * tested on Baikal-T1 based system with DW SPI-looped back interface transferring a chunk of data with DFS:8,12,16. Fixes: a51acc2400d4 ("spi: dw: Add support for 32-bits max xfer size") Suggested-by: Andy Shevchenko --- diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c index c3bfb6c..4976e3b 100644 --- a/drivers/spi/spi-dw-core.c +++ b/drivers/spi/spi-dw-core.c @@ -426,7 +426,10 @@ static int dw_spi_transfer_one(struct spi_controller *master, int ret; dws->dma_mapped = 0; - dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE); + dws->n_bytes = + roundup_pow_of_two(DIV_ROUND_UP(transfer->bits_per_word, + BITS_PER_BYTE)); + dws->tx = (void *)transfer->tx_buf; dws->tx_len = transfer->len / dws->n_bytes; dws->rx = transfer->rx_buf;