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authorMaxime Ripard <maxime.ripard@free-electrons.com>2017-01-27 22:38:33 +0100
committerUlf Hansson <ulf.hansson@linaro.org>2017-02-13 13:20:48 +0100
commit39cc281fb79e3d40e945577363a55f5c922353ad (patch)
treedfaee0afe993105e8efc24a4978fc8cecf8c388f /drivers/mmc
parent1ed2171944888cf6787990a0f6387b717ba72e24 (diff)
downloadlinux-39cc281fb79e3d40e945577363a55f5c922353ad.tar.bz2
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 <maxime.ripard@free-electrons.com> Tested-by: Florian Vaussard <florian.vaussard@heig-vd.ch> Acked-by: Chen-Yu Tsai <wens@csie.org> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/host/sunxi-mmc.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index b1d1303389a7..ab4324e6eb74 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;