The patch titled atmel_spi: clean up baud rate divisor calculation has been removed from the -mm tree. Its filename was atmel_spi-clean-up-baud-rate-divisor-calculation.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: atmel_spi: clean up baud rate divisor calculation From: Haavard Skinnemoen <haavard.skinnemoen@xxxxxxxxx> Make the baud rate divisor calculation code a bit more readable and add a few comments. Also fix wrong debug information being displayed when !new_1 and max_speed_hz == 0. [david-b@xxxxxxxxxxx: fix it] Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@xxxxxxxxx> Cc: "Janesh Ramakrishnan" <jramakrishnan@xxxxxxxxxxxxx> Acked-by David Brownell <david-b@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/atmel_spi.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff -puN drivers/spi/atmel_spi.c~atmel_spi-clean-up-baud-rate-divisor-calculation drivers/spi/atmel_spi.c --- a/drivers/spi/atmel_spi.c~atmel_spi-clean-up-baud-rate-divisor-calculation +++ a/drivers/spi/atmel_spi.c @@ -497,7 +497,7 @@ static int atmel_spi_setup(struct spi_de struct atmel_spi *as; u32 scbr, csr; unsigned int bits = spi->bits_per_word; - unsigned long bus_hz, sck_hz; + unsigned long bus_hz; unsigned int npcs_pin; int ret; @@ -536,14 +536,25 @@ static int atmel_spi_setup(struct spi_de return -EINVAL; } - /* speed zero convention is used by some upper layers */ + /* + * Pre-new_1 chips start out at half the peripheral + * bus speed. + */ bus_hz = clk_get_rate(as->clk); + if (!as->new_1) + bus_hz /= 2; + if (spi->max_speed_hz) { - /* assume div32/fdiv/mbz == 0 */ - if (!as->new_1) - bus_hz /= 2; - scbr = ((bus_hz + spi->max_speed_hz - 1) - / spi->max_speed_hz); + /* + * Calculate the lowest divider that satisfies the + * constraint, assuming div32/fdiv/mbz == 0. + */ + scbr = DIV_ROUND_UP(bus_hz, spi->max_speed_hz); + + /* + * If the resulting divider doesn't fit into the + * register bitfield, we can't satisfy the constraint. + */ if (scbr >= (1 << SPI_SCBR_SIZE)) { dev_dbg(&spi->dev, "setup: %d Hz too slow, scbr %u; min %ld Hz\n", @@ -551,8 +562,8 @@ static int atmel_spi_setup(struct spi_de return -EINVAL; } } else + /* speed zero means "as slow as possible" */ scbr = 0xff; - sck_hz = bus_hz / scbr; csr = SPI_BF(SCBR, scbr) | SPI_BF(BITS, bits - 8); if (spi->mode & SPI_CPOL) @@ -589,7 +600,7 @@ static int atmel_spi_setup(struct spi_de dev_dbg(&spi->dev, "setup: %lu Hz bpw %u mode 0x%x -> csr%d %08x\n", - sck_hz, bits, spi->mode, spi->chip_select, csr); + bus_hz / scbr, bits, spi->mode, spi->chip_select, csr); spi_writel(as, CSR0 + 4 * spi->chip_select, csr); _ Patches currently in -mm which might be from haavard.skinnemoen@xxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html