[PATCH 2/2] clk: sunxi-ng: sun50i: a64: Add 2x fixed post-divider to MMC module clocks
From: Maxime Ripard <hidden>
Date: 2017-12-05 20:00:12
Also in:
linux-clk, lkml
Hi, On Mon, Dec 04, 2017 at 01:19:12PM +0800, Chen-Yu Tsai wrote:
On the A64, the MMC module clocks are fixed in the new timing mode, i.e. they do not have a bit to select the mode. These clocks have a 2x divider somewhere between the clock and the MMC module. To be consistent with other SoCs supporting the new timing mode, we model the 2x divider as a fixed post-divider on the MMC module clocks. This patch adds the post-dividers to the MMC clocks. Signed-off-by: Chen-Yu Tsai <redacted>
I had a doubt applying that one... sorry.
quoted hunk ↗ jump to hunk
--- drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 57 +++++++++++++++++++++++------------ 1 file changed, 37 insertions(+), 20 deletions(-)diff --git a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c index 2bb4cabf802f..ee9c12cf3f08 100644 --- a/drivers/clk/sunxi-ng/ccu-sun50i-a64.c +++ b/drivers/clk/sunxi-ng/ccu-sun50i-a64.c@@ -400,28 +400,45 @@ static SUNXI_CCU_MP_WITH_MUX_GATE(nand_clk, "nand", mod0_default_parents, 0x080, BIT(31), /* gate */ 0); +/* + * MMC clocks are the new timing mode (see A83T & H3) variety, but without + * the mode switch. This means they have a 2x post divider between the clock + * and the MMC module. This is not documented in the manual, but is taken + * into consideration when setting the mmc module clocks in the BSP kernel. + * Without it, MMC performance is degraded. + * + * We model it here to be consistent with other SoCs supporting this mode. + * The alternative would be to add the 2x multiplier when setting the MMC + * module clock in the MMC driver, just for the A64. + */ static const char * const mmc_default_parents[] = { "osc24M", "pll-periph0-2x", "pll-periph1-2x" }; -static SUNXI_CCU_MP_WITH_MUX_GATE(mmc0_clk, "mmc0", mmc_default_parents, 0x088, - 0, 4, /* M */ - 16, 2, /* P */ - 24, 2, /* mux */ - BIT(31), /* gate */ - 0); - -static SUNXI_CCU_MP_WITH_MUX_GATE(mmc1_clk, "mmc1", mmc_default_parents, 0x08c, - 0, 4, /* M */ - 16, 2, /* P */ - 24, 2, /* mux */ - BIT(31), /* gate */ - 0); - -static SUNXI_CCU_MP_WITH_MUX_GATE(mmc2_clk, "mmc2", mmc_default_parents, 0x090, - 0, 4, /* M */ - 16, 2, /* P */ - 24, 2, /* mux */ - BIT(31), /* gate */ - 0); +static SUNXI_CCU_MP_WITH_MUX_GATE_POSTDIV(mmc0_clk, "mmc0", + mmc_default_parents, 0x088, + 0, 4, /* M */ + 16, 2, /* P */ + 24, 2, /* mux */ + BIT(31), /* gate */ + 2, /* post-div */ + 0); + +static SUNXI_CCU_MP_WITH_MUX_GATE_POSTDIV(mmc1_clk, "mmc1", + mmc_default_parents, 0x08c, + 0, 4, /* M */ + 16, 2, /* P */ + 24, 2, /* mux */ + BIT(31), /* gate */ + 2, /* post-div */ + 0); +
Are you sure that the divider there for the non-eMMC clocks? Usually, the new mode is only here for the eMMC, so we would divide the rate by two in the non-eMMC case. Maxime -- Maxime Ripard, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20171205/db1f3f9f/attachment.sig>