[Ovmsdev] External Wifi antenna

[Craig Leres]

On 1/30/21 11:58 PM, Michael Balzer wrote:
> congratulations to a successful heart transplantation :-)

With the right tools it was actually pretty easy. Certainly the hand 
soldering was easier than the CP2102 I swapped.

> Regarding RAM, I think you need to enable bank switching 
> (CONFIG_SPIRAM_BANKSWITCH_ENABLE).

Sounds like it's a little more complicated:

 
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/himem.html

     In order to use the himem API, you have to enable it in the
     menuconfig using CONFIG_SPIRAM_BANKSWITCH_ENABLE, as well as
     set the amount of banks reserved for this in
     CONFIG_SPIRAM_BANKSWITCH_RESERVE. This decreases the amount of
     external memory allocated by functions like malloc(), but it
     allows you to use the himem api to map any of the remaining
     memory into the reserved banks.

> Please also disable the PSRAM bug workaround and maybe do some 
> performance comparison. SPIRAM operations should run much faster without 
> the workaround.

What kind of tests should I run?

I'll might wait to disable the workaround until I upgrade my other 
production ovms unit.

 > Forgot to explain: to fully disable the PSRAM workaround, you also need
 > to modify main/component.mk:
 >
 > COMPONENT_ADD_LDFLAGS = -Wl,--whole-archive -l$(COMPONENT_NAME)
 > -Wl,--no-whole-archive -T main/ovms_boot.ld \
 >      -mfix-esp32-psram-cache-issue
 >
 > Remove the "-mfix-esp32-psram-cache-issue" here.

I did some testing and I think adding -mfix-esp32-psram-cache-issue to 
COMPONENT_ADD_LDFLAGS can be driven by the 
CONFIG_SPIRAM_CACHE_WORKAROUND define. I submitted a pull request to do 
this (but please check my work).

		Craig