From 97ab4250e778d195eba8874f3e9bcbdc830f4dbc Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Tue, 24 Mar 2015 16:12:08 -0700 Subject: rockchip/rk3288: Fix SPI clock divisor calculation The code to calculate the RK3288 SPI controller's internal clock divisor is wrong: it assumes that the divisor register was an "n-1" divisor when it actually isn't (due to some misleading kernel code that was copied in here). This means that all SPI clocks are currently running lower than expected. This patch fixes the calculation and changes all callers such that the effective speeds stay the same. BRANCH=veyron BUG=chrome-os-partner:38352 TEST=Booted Jerry with and without the patch, dumping the divisor for flash and EC clocks. Made sure it stays the same. Change-Id: I2336e2b81c2384b5076175fcf32717a3ab2ba0c5 Signed-off-by: Patrick Georgi Original-Commit-Id: 1fd5b990f937019a9bee7bd693c91d6e2fca1adb Original-Change-Id: I094d57a5933c8b849f5c66194e6cc2952ab68b90 Original-Signed-off-by: Julius Werner Original-Reviewed-on: https://chromium-review.googlesource.com/262269 Original-Reviewed-by: David Hendricks Reviewed-on: http://review.coreboot.org/9887 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer --- src/soc/rockchip/rk3288/spi.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'src/soc') diff --git a/src/soc/rockchip/rk3288/spi.c b/src/soc/rockchip/rk3288/spi.c index aa70f3e0e5..a8d2be30fc 100644 --- a/src/soc/rockchip/rk3288/spi.c +++ b/src/soc/rockchip/rk3288/spi.c @@ -94,12 +94,8 @@ static void rockchip_spi_enable_chip(struct rockchip_spi *regs, int enable) static void rockchip_spi_set_clk(struct rockchip_spi *regs, unsigned int hz) { - unsigned short clk_div = 0; - - /* Calculate clock divisor. */ - clk_div = SPI_SRCCLK_HZ / hz; - clk_div = (clk_div + 1) & 0xfffe; - assert((clk_div - 1) * hz == SPI_SRCCLK_HZ); + unsigned short clk_div = SPI_SRCCLK_HZ / hz; + assert(clk_div * hz == SPI_SRCCLK_HZ && !(clk_div & 1)); write32(®s->baudr, clk_div); } -- cgit v1.2.3