Summary of the Issue:
We have had customers reporting failure to run MC and SC production parts at 1GHz or higher frequencies. The signature of the fail is that the system will hang once it tries to ramp from the boot frequency of 800MHz to 1GHz or higher. The root cause was tracked to the setting of the LDO_VOLT_CHANGE_EN fuse in production parts. The LDO_VOLT_CHANGE_EN fuse sets the LDO boot voltage to either 1.15V (indicated by a fuse setting of “1”) or 1.1V (indicated by a fuse setting of “0”). In production parts the fuse is set to “1”, i.e. 1.15V, since this is the optimal setting based on characterization data. On pre-production units the LDO voltage was set to the lower setting of 1.1V (i.e. fuse set to “0”). The reason this is a problem with MC/SC parts is because the fuse is read by the ROM during boot and overwrites the LDO ramp rate bits in the PMU_MISC2 register based on the setting of the fuse. When the LDO_VOLT_CHANG_EN fuse is set to “1” then the LDO ramp up time to spec voltage is set (in PMU_MISC2) to 500uS instead of the 50uS assumed by the CPUFreq driver. This will cause the system to hang when transitioning from the boot frequency to a higher frequency/voltage point since the required voltage to support the higher frequency is not yet present. In real terms, customers who have production i.MX 6Quad/6Dual/6DualLite and 6 Solo parts have seen failures to ramp their products to 1GHz or higher frequencies. This is completely fixed by a software patch that corrects the LDO ramp setting in the PMU_MISC_2 register by setting it back to the fastest ramp time.
Note that the LDO_VOLT_CHANGE_EN fuse is not in the reference manual since it is not a customer visible fuse. It is programmed and locked at final test.
This is a mandatory fix for all customers.
- i.MX 6Quad – all SC and MC parts, consumer and automotive. Industrial MC parts not yet shipping.
- i.MX 6Dual – all SC and MC parts, consumer and automotive. Industrial MC parts not yet shipping.
- i.MX 6DualLite – all MC parts consumer parts. Automotive and industrial MC parts not yet shipping.
- i.MX 6Solo – all MC consumer parts. Automotive and industrial MC parts not yet shipping.
Patch Availability and Location:
Patches exist for both Linux and Android. They are available on freescale.com. See below for more details.
- i.MX 6Quad – www.freescale.com/imx6q
- i.MX 6Dual – www.freescale.com/imx6d
- i.MX 6DualLite – www.freescale.com/imx6dl
- i.MX 6Solo – www.freescale.com/imx6s
Select the “Software and Tools” tab and then expand the section “Updates and Patches”. The relevant patches are:
Linux – L3.0.35_1.1.1_LDO_PATCH (i.MX 6Quad/6Dual)
Linux – L3.0.35_3.0.3_LDO_PATCH (i.MX 6DualLite/6Solo)
Android – IMX6_R13.4103_ANDROID_LDO_PATCH (i.MX 6Quad/6Dual/6DualLite/6Solo)
- i.MX FAE’s: done (via maillist). Will post copy of this email to i.MX support space by end of day 1st March.
- i.MX DFAE’s: 8th March.
- Customer notification: 8th March.
- i.MX community: 8th March (to coincide with customer notification).
- We are also working on an engineering bulletin that describes the change for customers who are not using our provided Linux and Android BSP’s. Target date: TBD. But goal is to make this available on/around mid-March.
Amanda and Kyle
This document was generated from the following discussion: i.MX 6 Series LDO Ramp Issue: Linux and Android Patches Now Available