AM6442: Quickest boot - OSPI or QSPI

Hi Daniel,

a couple of quick general comments;

• OSPI would be recommended for fastest boot; more parallel data lines == higher throughput
• Highest frequency is defined in the device datasheet; you can run the OSPI controller/module w/ 166MHz bus speed in DDR mode; this is supported by the current driver. The SK-AM64B board is a good example of such a solution.
• The higher speeds require the use of what's called "PHY Mode" which requires a careful HW design including the connections and clock signals and also requires only a single flash device to be connected (no muxing with different OSPI/QSPI devices using the chip select signals, also see AM6442, AM6422, AM6412 and AM2434 Schematic Design and Review Checklist for more background on this and other HW-related aspects)
• The external loopback mode is only used for QSPI according to the TRM section "12.3.2.4.2 OSPI Modes". In case of OSPI, the external device provides a DQS signal for source synchronous capture.

Daniel Sommerfeldt said:

I read in e2e that there is a problem with OSPI boot, better to use xSPI?

OSPI boot works as advertised in the TRM. Whether OSPI or xSPI needs to be used depends on the OSPI device protocol support/requirements. If you have a specific question/concern, let us know.

Daniel Sommerfeldt said:

We need to boot as quick as possible (<3-5s)

As for optimizing boot time, there's many optimizations that can be done, but the boot times you need should be achievable. Consider using a "Falcon Boot" type approach, going directly from R5 U-Boot SPL (the initial boot stage) to the Linux Kernel, which brings a very large improvement, see https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1205638/faq-am625-how-to-boot-from-r5-u-boot-spl-directly-into-the-linux-kernel-skipping-a53-spl-and-a53-u-boot-falcon-mode for an example implementation.

Regards, Andreas