On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be loaded directly from an EEPROM or, if not present, by the SoC's co-processor, VideoCore. This series adds support for the later. Note that there are a set of constraints we have to consider (some of them I missed on v1): - We need to make sure the VideoCore firmware interface is up and running before running the VL805 firmware load call. - There is no way to discern RPi4's VL805 chip from other platforms', so we need the firmware load to happen *before* running quirk_usb_handoff_xhci(). Failure to do so results in an unwarranted 5 second wait while the fixup code polls xHC's unexisting state. By Florian's suggestion I've been spending some time exploring the device link[1] API in order to see if that could save us from explicitly creating probe dependencies between pcie-brcmstb and firmware/raspberrypi (patch #3). Technically these dependencies could be inferred from DT. It turns out Saravana Kannan has been looking at this already. A new boot mechanism, activated with fw_devlink=on takes care of the device probe ordering on devices with consumer/supplier relationships. For now this relationship is created based on the usage of generic DT properties, but has no support for vendor-specifc DT properties, which we'd be forced to use in order to create a relationship between our two devices since our setup is highly non generic. There will probably be at some point support for such properties, and we will then be able to revisit some of this code. All this is based on the work by Tim Gover in RPi's downstream kernel[2]. [1] https://www.kernel.org/doc/html/v4.13/driver-api/device_link.html [2] https://github.com/raspberrypi/linux/commit/9935b4c7e360b4494b4cb6e3ce797238a1ab78bd --- Changes since v6: - Make rpi_firmware_init_vl805() more robust - Rewrite comments and patch descriptions to be more accessible to non RPi fluent people - Removed Florian's Reviewed-by in patch #2 as function changed substantially - Tested with/witout u-boot Changes since v5: - Fix issues reported by Kbuild test robot Changes since v4: - Addressed Sergei's comments - Fix potential warning in patch #2 Changes since v3: - Addressed Greg's comments There was no v2, my bad. Changes since v1: - Addressed Floarians comments Nicolas Saenz Julienne (4): soc: bcm2835: Add notify xHCI reset property firmware: raspberrypi: Introduce vl805 init routine PCI: brcmstb: Wait for Raspberry Pi's firmware when present USB: pci-quirks: Add Raspberry Pi 4 quirk drivers/firmware/Kconfig | 3 +- drivers/firmware/raspberrypi.c | 52 ++++++++++++++++++++++ drivers/pci/controller/pcie-brcmstb.c | 17 +++++++ drivers/usb/host/pci-quirks.c | 16 +++++++ include/soc/bcm2835/raspberrypi-firmware.h | 9 +++- 5 files changed, 95 insertions(+), 2 deletions(-) -- 2.26.2
