When two CPUs read the area of the DPORT and the area of the APB, the result is corrupted for the CPU that read the APB area.
And another CPU has valid data.
The method of eliminating this error.
Before reading the registers of the DPORT, make a preliminary reading of the APB register.
In this case, the joint access of the two CPUs to the registers of the APB and the DPORT is successful.
If two different types of SHA hashes were active in the hardware
concurrently, a race condition meant the SHA unit could be incorrectly
reset leading to all-zero results.
1. When dual core cpu run access DPORT register, must do protection.
2. If access DPORT register, must use DPORT_REG_READ/DPORT_REG_WRITE and DPORT_XXX register operation macro.
SHA hardware allows each of SHA1, SHA256, SHA384&SHA512 to calculate digests
concurrently.
Currently incompatible with AES acceleration due to a hardware reset problem.
Ref TW7111.
Should protect against concurrent use of hardware crypto primitives,
with good performance.
Not necessary to call esp_aes_acquire_hardware(),
esp_sha_acquire_hardware(), etc when using these APIs. These are
provided for external users calling the hardware crypto hardware
directly, to coexist with this implementation.
Konstantin Kondrashov