From 39cc281fb79e3d40e945577363a55f5c922353ad Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 27 Jan 2017 22:38:33 +0100 Subject: [PATCH] mmc: sunxi: Fix clock frequency change sequence The SD specification documents that the clock frequency should only be changed once gated (Section 3.2.3 - SD Clock Frequency Change Sequence). The current code first modifies the parent clock, gates it and then modifies the internal divider. This means that since the parent clock rate might be changed, the bus clock might be changed as well before it is gated, which breaks the specification. Move the gating before the parent rate modification. Signed-off-by: Maxime Ripard Tested-by: Florian Vaussard Acked-by: Chen-Yu Tsai Signed-off-by: Ulf Hansson --- drivers/mmc/host/sunxi-mmc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c index b1d1303..ab4324e 100644 --- a/drivers/mmc/host/sunxi-mmc.c +++ b/drivers/mmc/host/sunxi-mmc.c @@ -761,6 +761,10 @@ static int sunxi_mmc_clk_set_rate(struct sunxi_mmc_host *host, u32 rval, clock = ios->clock; int ret; + ret = sunxi_mmc_oclk_onoff(host, 0); + if (ret) + return ret; + /* 8 bit DDR requires a higher module clock */ if (ios->timing == MMC_TIMING_MMC_DDR52 && ios->bus_width == MMC_BUS_WIDTH_8) @@ -783,10 +787,6 @@ static int sunxi_mmc_clk_set_rate(struct sunxi_mmc_host *host, return ret; } - ret = sunxi_mmc_oclk_onoff(host, 0); - if (ret) - return ret; - /* clear internal divider */ rval = mmc_readl(host, REG_CLKCR); rval &= ~0xff; -- 2.7.4