Dear all, I need urgent clarifications about this issue.
Looking at Sitara SDK 5.3.2.0 Release Note a new critical issue ARM_MPU.KERNEL.39 has arisen: DMA support in Mentor MUSB driver is considered unstable and therefore it is suggested to disable it (of course with performance degradation).
The issue affects all platforms, i.e. AM180x and AM335x too: in fact in both platform Kernel configurations CONFIG_USB_TI_CPPI41_DMA has been replaced by CONFIG_MUSB_PIO_ONLY, and looking at Kconfig the following comment has appeared: "MUSB_PIO_ONLY ... On CPPI 4.1 DMA based systems (AM335x, AM35x, and AM180x) DMA support is considered unstable and this option should be enabled in production". This surprises me because AM180x and AM335x have different ARM core architectures and also different PSP and Kernel versions, so I am wondering about the root cause of this issue: HW or SW?
It would be nice to have some clarifications about that, because planning to develop USB-based products with no DMA will have critical impact on.
I am also wondering if the same issue affects AM180x with Kernel 2.6.32 from older PSP (Sitara SDK 4.01).
Not sure this is the best forum, or Kernel one instead. I am interested in both AM1808 and AM335x products. Please move to the more appropriate.
Regards, Max