Hi all, On Thu, Feb 2, 2023 at 10:04 AM Pali Rohár <p...@kernel.org> wrote: > > On Wednesday 01 February 2023 13:13:16 Tony Dinh wrote: > > Hi all, > > > > On Wed, Feb 1, 2023 at 11:05 AM Pali Rohár <p...@kernel.org> wrote: > > > > > > On Wednesday 01 February 2023 09:17:15 Michael Walle wrote: > > > > > > > When DM_SERIAL is enabled, the device-tree property dm-pre-reloc > > > > > > > is > > > > > > > required to boot over UART with kwboot. Enable this in a Kirkwood > > > > > > > common u-boot dtsi. > > > > > > > > > > > > My (dev) board unfortunately, have a bootloader which can't boot > > > > > > over > > > > > > serial. > > > > > > > > > > This is feature of Marvell BootROM and does not require any special > > > > > from > > > > > Bootloader. So you should be able to boot over UART (if you have > > > > > accessible pins). > > > > > > > > I know, but there are known versions ob the bootrom where uart boot > > > > isn't supported (correctly). > > > > > > I heard about it... maybe it is a bug in client software (kwboot)? I do > > > not have such board if you are interested in it I could try to send some > > > details how to debug it. > > > > The Kirkwood SoCs came with different BootROM versions. Version 1.1 > > cannot be booted over UART, but version 1.2 can. I think there must > > be a bug in the BootROM 1.1. The older Kirkwood such as Sheevaplug, > > Dockstar, iConnect boards come with BootROM 1.1. Later version of > > Sheevaplug, GoFlex Home, GoFlex Net, Dreamplug, Pogoplug V4, Zyxel > > NSA310S, NSA320, NSA325 come with BootROM 1.2. So even though it is > > the same SoC, eg. 6281, they are actually produced at a different time > > and have different BootROM versions. > > There are always multiple revisions of the same SoC. So it is possible > that something was broken on first revision of 88F6281 and in next > revision was updated BootROM with some fixes. Revision is written on > package label and for Armada SoCs it is available also in some register > (not sure about Kirkwood). It looks like that there is at least revision > Z0 and revision A0 of some Kirkwood SoC. > > If there is a bug in first revisions then it should be documented in > some Kirkwood Errata document. Unfortunately I have never seen it, it is > not public, so I have no idea. In any case, if somebody has access to > Marvell documents, interesting are these document numbers: > > * MV-S105223-001 - Differences Between the 88F6192, and 88F6281 Stepping Z0 > and A0 > * MV-S501081-00 - 88F6180, 88F6192, and 88F6281 Functional Errata, Interface > Guidelines, and Restrictions > * MV-S501157-U0 - 88F6180, 88F6190, 88F6192, and 88F6281 Functional Errata, > Interface Guidelines, and Restrictions > > One of the option how to investigate or debug this issue without > documentation is to dump both BootROM versions (1.1, 1.2) and compare > them. Either there is different UART protocol for booting (which needs > to be implemented) or UART protocol is buggy and needs some workaround > or it is completely broken and does not work.
Here is an excerpt from doc/develop/driver-model/serial-howto.rst. Quote === Here are some things you might need to consider: 1. The serial driver itself needs to be present before relocation, so that the U-Boot banner appears. Make sure it has a u-boot,dm-pre-reloc tag in the device tree, so that the serial driver is bound when U-Boot starts. For example, on iMX8:: lpuart3: serial@5a090000 { compatible = "fsl,imx8qm-lpuart"; ... }; put this in your xxx-u-boot.dtsi file:: &lpuart3 { u-boot,dm-pre-proper; }; === Unquote So it looks like my understanding was correct. The serial driver is not bound if there is no u-boot,dm-pre-reloc tag. And does it sound like it is required for all targets because of this reason? Thanks, Tony