Hi Eric,


On 17 May 2017 at 16:45, Eric Nelson [off-list ref] wrote:

Hi Fawad,

On 05/17/2017 06:40 AM, Fawad Lateef wrote:

quoted

On 15 May 2017 at 16:20, Fawad Lateef [off-list ref] wrote:

quoted

Hi Eric,
On 15 May 2017 at 16:12, Eric Nelson [off-list ref] wrote:

quoted

Hi Fawad,

quoted

????????
On 05/15/2017 20:44, Fawad Lateef wrote:

Hi All,

I am working on custom i.MX6 quad hardware and using RT patches for
almost latest stable kernel 4.9 and facing some weird system stall OR
'unhandled page fault - exceptions'.

I'm not sure about the unhandled page fault, but the stalls may be
because of the SDMA driver.

See this patch in the Freescale/NXP community for kernel 4.1:

https://github.com/Freescale/meta-freescale/blob/master/recipes-kernel/linux/linux-fslc-imx-rt/0003-Work-around-CPU-stalls-in-the-imx-sdma-driver.patch

Thanks for the patch link. I will give it a try.

Talked to hardware manufacturer and they applied the patch.

Still that SDMA is only used for NOR flash and only u-boot and its
environment are stored in nor flash. So not sure if that is going to
help in any case.

SDMA is used for much more than NOR flash (SSI, USB, and sometimes
UARTs).

Yes SDMA can be used for many devices but in our case its only set to
use for NOR (to confirm I also checked sdma interrupts in system and
they just 21 or so which happened during boot time).

quoted

So I would really like few more suggestions OR confirmations about ARM
(cortex-A9 based imx6) (preemept)-RT support/patches are stable and
can be used for final products.

I don't have any experience with the RT patches on 4.9 or later
kernels, but do know that they're being used on i.MX6 with the
vendor kernels (3.10.x, 4.1.x).

I believe Alison Chaiken mentioned using them with 4.9 kernels:
http://elinux.org/images/4/42/IRQs-_the_Hard%2C_the_Soft%2C_the_Threaded_and_the_Preemptible.pdf
https://www.youtube.com/watch?v=-pehAzaP1eg&feature=youtu.be&list=PLbzoR-pLrL6pRFP6SOywVJWdEHlmQE51q

Thanks for the video/link. Seems like very informative. Will check it soon.

Regards,


Eric

Regards,

Fawad Lateef