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Commit 210b4923 authored by Martin Sperl's avatar Martin Sperl Committed by Mark Brown
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spi: bcm2835: clock divider can be a multiple of 2 



The official documentation is wrong in this respect.
Has been tested empirically for dividers 2-1024

Signed-off-by: default avatarMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 4adf3129

drivers/spi/spi-bcm2835.c

+3 −2
Original line number Diff line number Diff line
@@ -153,8 +153,9 @@ static int bcm2835_spi_start_transfer(struct spi_device *spi, 
	if (spi_hz >= clk_hz / 2) {

		cdiv = 2; /* clk_hz/2 is the fastest we can go */

	} else if (spi_hz) {

		/* CDIV must be a power of two */

		cdiv = roundup_pow_of_two(DIV_ROUND_UP(clk_hz, spi_hz));

		/* CDIV must be a multiple of two */

		cdiv = DIV_ROUND_UP(clk_hz, spi_hz);

		cdiv += (cdiv % 2);



		if (cdiv >= 65536)

			cdiv = 0; /* 0 is the slowest we can go */