[PATCH] clk: ti: omap5+: dpll: implement errata i810
Tero Kristo
t-kristo at ti.com
Mon Nov 30 06:43:25 PST 2015
Errata i810 states that DPLL controller can get stuck while transitioning
to a power saving state, while its M/N ratio is being re-programmed.
As a workaround, before re-programming the M/N ratio, SW has to ensure
the DPLL cannot start an idle state transition. SW can disable DPLL
idling by setting the DPLL AUTO_DPLL_MODE=0 or keeping a clock request
active by setting a dependent clock domain in SW_WKUP.
This errata impacts OMAP5 and DRA7 chips, so enable the errata for these.
Signed-off-by: Tero Kristo <t-kristo at ti.com>
---
arch/arm/mach-omap2/clock.c | 4 ++++
drivers/clk/ti/dpll3xxx.c | 25 ++++++++++++++++++++++++-
include/linux/clk/ti.h | 1 +
3 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index acb60ed..d058125 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -225,5 +225,9 @@ void __init ti_clk_init_features(void)
if (omap_rev() == OMAP3430_REV_ES1_0)
features.flags |= TI_CLK_DPLL4_DENY_REPROGRAM;
+ /* Errata I810 for omap5 / dra7 */
+ if (soc_is_omap54xx() || soc_is_dra7xx())
+ features.flags |= TI_CLK_ERRATA_I810;
+
ti_clk_setup_features(&features);
}
diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c
index f4dec00..1c30038 100644
--- a/drivers/clk/ti/dpll3xxx.c
+++ b/drivers/clk/ti/dpll3xxx.c
@@ -305,8 +305,9 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n)
static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
{
struct dpll_data *dd = clk->dpll_data;
- u8 dco, sd_div;
+ u8 dco, sd_div, ai = 0;
u32 v;
+ bool errata_i810;
/* 3430 ES2 TRM: 4.7.6.9 DPLL Programming Sequence */
_omap3_noncore_dpll_bypass(clk);
@@ -350,6 +351,25 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
v |= sd_div << __ffs(dd->sddiv_mask);
}
+ /*
+ * Errata i810 - DPLL controller can get stuck while transitioning
+ * to a power saving state. Software must ensure the DPLL can not
+ * transition to a low power state while changing M/N values.
+ * Easiest way to accomplish this is to prevent DPLL autoidle
+ * before doing the M/N re-program.
+ */
+ errata_i810 = ti_clk_get_features()->flags & TI_CLK_ERRATA_I810;
+
+ if (errata_i810) {
+ ai = omap3_dpll_autoidle_read(clk);
+ if (ai) {
+ omap3_dpll_deny_idle(clk);
+
+ /* OCP barrier */
+ omap3_dpll_autoidle_read(clk);
+ }
+ }
+
ti_clk_ll_ops->clk_writel(v, dd->mult_div1_reg);
/* Set 4X multiplier and low-power mode */
@@ -379,6 +399,9 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel)
_omap3_noncore_dpll_lock(clk);
+ if (errata_i810 && ai)
+ omap3_dpll_allow_idle(clk);
+
return 0;
}
diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index 223be69..75205df 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -286,6 +286,7 @@ struct ti_clk_features {
#define TI_CLK_DPLL_HAS_FREQSEL BIT(0)
#define TI_CLK_DPLL4_DENY_REPROGRAM BIT(1)
#define TI_CLK_DISABLE_CLKDM_CONTROL BIT(2)
+#define TI_CLK_ERRATA_I810 BIT(3)
void ti_clk_setup_features(struct ti_clk_features *features);
const struct ti_clk_features *ti_clk_get_features(void);
--
1.7.9.5
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