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 > <nsaenzjulie...@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
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