Right now if you've got earlyprintk enabled on exynos5420-peach-pit then you'll get a hang on boot. Here's why:
1. The i2c-s3c2410 driver will probe at subsys_initcall. It will enable its clock and disable it. This is the clock "i2c2". 2. The act of disabling "i2c2" will disable its parents. In this case the parent is "aclk66_peric". There are no other children of "aclk66_peric" officially enabled, so "aclk66_peric" will be turned off (despite being CLK_IGNORE_UNUSED, but that's by design). 3. The next time you try to earlyprintk you'll do so without the UART clock enabled. That's because the UART clocks are also children of "aclk66_peric". You'll hang. There's no good place to put a clock enable for earlyprintk, which is handled by a bunch of assembly code. The best we can do is to handle this in the clock driver. Signed-off-by: Doug Anderson <[email protected]> Tested-by: Javier Martinez Canillas <[email protected]> --- Changes in v2: - Use GATE_A and clk_get(). Save the clock for putting later. - Return 0 from exynos5420_clk_late_init(). drivers/clk/samsung/clk-exynos5420.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/drivers/clk/samsung/clk-exynos5420.c b/drivers/clk/samsung/clk-exynos5420.c index 9d7d7ee..70b607a 100644 --- a/drivers/clk/samsung/clk-exynos5420.c +++ b/drivers/clk/samsung/clk-exynos5420.c @@ -890,8 +890,8 @@ static struct samsung_gate_clock exynos5x_gate_clks[] __initdata = { GATE_BUS_TOP, 9, CLK_IGNORE_UNUSED, 0), GATE(0, "aclk66_psgen", "mout_user_aclk66_psgen", GATE_BUS_TOP, 10, CLK_IGNORE_UNUSED, 0), - GATE(CLK_ACLK66_PERIC, "aclk66_peric", "mout_user_aclk66_peric", - GATE_BUS_TOP, 11, CLK_IGNORE_UNUSED, 0), + GATE_A(CLK_ACLK66_PERIC, "aclk66_peric", "mout_user_aclk66_peric", + GATE_BUS_TOP, 11, CLK_IGNORE_UNUSED, 0, "aclk66_peric"), GATE(0, "aclk266_isp", "mout_user_aclk266_isp", GATE_BUS_TOP, 13, 0, 0), GATE(0, "aclk166", "mout_user_aclk166", @@ -1172,11 +1172,22 @@ static struct of_device_id ext_clk_match[] __initdata = { { }, }; +/* Keep these clocks on until late_initcall */ +struct boot_clock { + char *name; + struct clk *clk; +}; + +static struct boot_clock boot_clocks[] __initdata = { + { .name = "aclk66_peric", }, +}; + /* register exynos5420 clocks */ static void __init exynos5x_clk_init(struct device_node *np, enum exynos5x_soc soc) { struct samsung_clk_provider *ctx; + int i; if (np) { reg_base = of_iomap(np, 0); @@ -1226,6 +1237,11 @@ static void __init exynos5x_clk_init(struct device_node *np, } exynos5420_clk_sleep_init(); + + for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) { + boot_clocks[i].clk = clk_get(NULL, boot_clocks[i].name); + clk_prepare_enable(boot_clocks[i].clk); + } } static void __init exynos5420_clk_init(struct device_node *np) @@ -1239,3 +1255,16 @@ static void __init exynos5800_clk_init(struct device_node *np) exynos5x_clk_init(np, EXYNOS5800); } CLK_OF_DECLARE(exynos5800_clk, "samsung,exynos5800-clock", exynos5800_clk_init); + +static int __init exynos5420_clk_late_init(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(boot_clocks); i++) { + clk_disable_unprepare(boot_clocks[i].clk); + clk_put(boot_clocks[i].clk); + } + + return 0; +} +late_initcall(exynos5420_clk_late_init); -- 1.9.1.423.g4596e3a -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
