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authorYuan Jiangli <jlyuan@motorola.com>2012-03-06 12:51:12 -0600
committerTony Lindgren <tony@atomide.com>2012-03-06 16:13:50 -0800
commit3223d007a3f9ddbd68424adf628e740dd87c564f (patch)
treeded5e0942403e6ef09787a2fbbe319896ec2e2bc /arch/arm/mach-omap2/vp.c
parentbb1dbe7cfd62e35f6f25e94729458b9047e3f555 (diff)
ARM: OMAP3+: PM: VP: fix integer truncation error
commit 2f34ce81b8c05c900e45bd88595cc154f7bb5957 (OMAP3: PM: Adding voltage driver support.) introduced runtime computation of waittime to handle all potential sys clocks available. In the voltage processor, the SPMSUpdateWait is calculated based on the slew rate and the voltage step (SMPSUpdateWait = slew rate * Voltage Step). After the voltage processor receives the SMPS_Ack signal, the Voltage Controller will wait for SMPSUpdateWait clock cycles for the voltage to settle to the new value. For all practical purposes, the waittime parameter is the OMAP hardware translation of what the slew rate on the PMIC is. As an example, with TPS62361 on OMAP4460, step_size = 10000 slew_rate = 32000 sys_clk_rate = 38400 Our current computation results in the following: = ((step_size / slew_rate) * sys_clk_rate) / 1000 = ((10000 / 32000) * 38400 / 1000 = 0 Fix the same using DIV_ROUND_UP as an extra wait clock cycle is better than lesser clock cycle. For the above example, this translates to: = (10000 * 38400) / (1000 * 32000) = 12 Acked-by: Jon Hunter <jon-hunter@ti.com> [nm@ti.com: slightly better implementation] Signed-off-by: Nishanth Menon <nm@ti.com> Signed-off-by: Yuan Jiangli <jlyuan@motorola.com> Acked-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
Diffstat (limited to 'arch/arm/mach-omap2/vp.c')
-rw-r--r--arch/arm/mach-omap2/vp.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm/mach-omap2/vp.c b/arch/arm/mach-omap2/vp.c
index 0df88820978..f95c1bad9dc 100644
--- a/arch/arm/mach-omap2/vp.c
+++ b/arch/arm/mach-omap2/vp.c
@@ -61,8 +61,8 @@ void __init omap_vp_init(struct voltagedomain *voltdm)
vddmin = voltdm->pmic->vp_vddmin;
vddmax = voltdm->pmic->vp_vddmax;
- waittime = ((voltdm->pmic->step_size / voltdm->pmic->slew_rate) *
- sys_clk_rate) / 1000;
+ waittime = DIV_ROUND_UP(voltdm->pmic->step_size * sys_clk_rate,
+ 1000 * voltdm->pmic->slew_rate);
vstepmin = voltdm->pmic->vp_vstepmin;
vstepmax = voltdm->pmic->vp_vstepmax;