The driver decide whether use MOSI/MISO phases according to the buffer
address together with the SPI_TRANS_USE_*DATA. However someone may assue
that these phases will be skipped when the ``length``/``rxlength`` is
set to 0. In fact it is a feature that ``rxlength`` is allowed to be
set to 0 when tx and rx have the same length, and the driver fill the
``rxlength`` to ``length``.
An error check is added when the rxlength is 0 but there is data to be
sent.
Introduced in 9c23b8e5 and 4f87a62f. To get higher speed, menuconfig
options are added to put ISR and other functions into the IRAM. The
interrupt flag ESP_INTR_FLAG_IRAM is also mistakenly set when the ISR is
put into the IRAM. However callbacks, which are wrote by the user, are
called in the master and slave ISR. The user may not be aware of that
these callbacks are not disabled during flash operations. Any cache miss
during flash operation will cause panic.
Essentially IRAM functions and intrrupt flag ESP_INTR_FLAG_IRAM are
different, the latter means not disabling the ISR during flash
operations. New bus_config flag intr_flags is offered to help set the
interrupt attribute, including priority level, SHARED, IRAM (not
disabled during flash operations). It introduced a small BREAK to
IDFv3.1 (but the same as IDFv3.0) that the user has to manually set IRAM
flag now (therefore he's aware of the IRAM thing) to void the ISR being
disabled during flash operations.
The MISO signal will be delayed if the GPIO matrix is enabled.
However, delay also comes from the slave.
Previous code only considers the former case, and assume the frequency
limitations is only violated when GPIO matrix is used.
Now we are able to calculate the freq limit when extenal MISO delay is
given (feature introduced in 9c6c6ec34ab0641ace89aeb9b1a133eb6fae1a18).
The frequency limit is lower when the external MISO delay is large, and
the limit is likely to be violated even with IOMUX.
Resolves https://github.com/espressif/esp-idf/issues/2690.
The address field should be placed at the highest bits of address and slv_wr_status registers. Instead of breaking the address into two parts and fill in each register, move the address to the highest bits and write to the registers respectively.
Breaking change: if you fill-in the SPI address filed in a previous version in some way and it works correctly, you still have to rewrite the address, in a more intuitive way.
force rxlength=length and mosi=1 and inlink.start=1 on in full-duplex mode.
set rxlength > length is forbidden in full-duplex mode.
TW#12609, TW#14240, https://www.esp32.com/viewtopic.php?f=13&t=2519
