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spi/rockchip: fix bug that case spi can't go as fast as slave request 

Because the minimum divisor in rk3x's spi controller is 2,
if spi_clk is less than 2 * sclk_out, we can't get the right divisor.
So we must set spi_clk again to match slave request.

Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Addy Ke 2014-10-15 19:25:49 +08:00 committed by Mark Brown
parent a2285b8c75
commit f9cfd52262
1 changed files with 12 additions and 0 deletions
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12
drivers/spi/spi-rockchip.c
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@ -145,6 +145,9 @@
#define RXBUSY (1 << 0)
#define TXBUSY (1 << 1)
/* sclk_out: spi master internal logic in rk3x can support 50Mhz */
#define MAX_SCLK_OUT 50000000
enum rockchip_ssi_type {
SSI_MOTO_SPI = 0,
SSI_TI_SSP,
@ -496,6 +499,15 @@ static void rockchip_spi_config(struct rockchip_spi *rs)
dmacr |= RF_DMA_EN;
}
if (WARN_ON(rs->speed > MAX_SCLK_OUT))
rs->speed = MAX_SCLK_OUT;
/* the minimum divsor is 2 */
if (rs->max_freq < 2 * rs->speed) {
clk_set_rate(rs->spiclk, 2 * rs->speed);
rs->max_freq = clk_get_rate(rs->spiclk);
}
/* div doesn't support odd number */
div = max_t(u32, rs->max_freq / rs->speed, 1);
div = (div + 1) & 0xfffe;