Hi Bin,
On Wed, 2020-05-06 at 13:33 +0800, Bin Meng wrote:
Hi Nicolas,
On Wed, May 6, 2020 at 12:26 AM Nicolas Saenz Julienne nsaenzjulienne@suse.de wrote:
On the Raspberry Pi 4, after a PCI reset, VL805's (a xHCI chip) firmware may either be loaded directly from an EEPROM or, if not present, by the SoC's VideCore (the SoC's co-processor). Introduce the function that informs VideCore that VL805 may need its firmware loaded.
I still did not get it. Without the firmware being loaded, does xHCI on RPi 4 still work?
On newer revisions of RPi4, no, it will not work.
What exact functionality does the firmware provide?
It provides xHCI functionality.
The old RPi4 design loaded this vl805 firmware trough a dedicated EEPROM memory. But they removed it, probably in order to save costs. They then created this new interface to trigger a firmware load from RPi4's co-processor.
Regards, Nicolas