Hello, This series adds support for USB DFU boot on TI's AM62A SoC which has two instances of DWC3 USB Controllers namely USB0 and USB1. The USB0 instance of the USB Controller supports USB DFU boot: ROM => tiboot3.bin => tispl.bin => u-boot.img
USB DFU Boot requires the USB Controller to be configured for Gadget mode of operation. Since the USB0 instance of the DWC3 USB Controller supports both Host and Gadget modes of operation via the Type-C interface on the AM62A7-SK board, the device-tree specifies the "dr_mode" as "OTG". The function dwc3_generic_probe() is invoked by either of: 1. dwc3_generic_peripheral_probe() 2. dwc3_generic_host_probe() on the basis of the command executed by the user for either device or host mode of operation respectively. Currently, dwc3_generic_probe() sets the mode based on the device-tree rather than setting it on the basis of the caller. While this might be correct when the mode is "host" or "peripheral" in the device-tree, it is wrong when the mode is "otg" in the device-tree. It is wrong because of two reasons: 1. There is no OTG state machine in U-Boot. Hence the role will never switch to the correct one eventually among host or peripheral. 2. dr_mode = "otg" results in the "PRTCAPDIR" field of the "GCTL" register of the USB Controller being set to 11b. According to the datasheet of the Designware USB Dual Role Controller, "PRTCAPDIR" should never be set to any value other than 01b (Host) and 10b (Device). Quoting the datasheet: "Programming this field with random data causes the controller to keep toggling between the host mode and the device mode." Therefore, in order to avoid programming 11b in "PRTCAPDIR", and, given that the caller specifies the intended role, rather than simply using the "dr_mode" property to set the role, set the role on the basis of the caller (intended role) and the device-tree (platform support). This could be extended further to utilize the USB ID pin to determine the expected role, but that can be implemented as an incremental feature. v1: https://patchwork.ozlabs.org/project/uboot/list/?series=434253&state=%2A&archive=both Changes since v1: - Rebased series on commit acab6e78aca common: relocate fdt_blob in global_data for FDTSRC_EMBED case of the master branch of U-Boot. - Based on the feedback received on the v1 series, the device-tree specified role is also taken into account in dwc3_generic_probe(), in addition to the caller of dwc3_generic_probe(). In addition to the patches in this series, the following device-tree changes will be required to test USB DFU on AM62A (bootph-all property to be added to ensure that USB Controller is present at all stages for DFU Boot): https://gist.github.com/Siddharth-Vadapalli-at-TI/53ba02cb0ff4a09c47e920d08247065f The above device-tree changes will be made to the Linux device-tree, which shall ensure that the same shall be a part of U-Boot device-tree eventually. The USB DFU config fragments for AM62x have been used for enabling USB DFU boot on AM62a as follows: R5 => am62ax_evm_r5_defconfig + am62x_r5_usbdfu.config A53 => am62ax_evm_a53_defconfig + am62x_a53_usbdfu.config Logs validating USB DFU boot with this series on AM62A7-SK: https://gist.github.com/Siddharth-Vadapalli-at-TI/13f9a539ef3297ab2822bc1bc1976a7f Regards, Siddharth. Siddharth Vadapalli (2): usb: dwc3-generic: set "mode" based on caller of dwc3_generic_probe() board: ti: am62ax: env: include environment for DFU board/ti/am62ax/am62ax.env | 1 + drivers/usb/dwc3/dwc3-generic.c | 21 +++++++++++++++++---- 2 files changed, 18 insertions(+), 4 deletions(-) -- 2.43.0
