Hi Geert, On Mon, Mar 09, 2020 at 11:32:06AM +0100, Geert Uytterhoeven wrote: > Hi Chunyan, > > On Mon, Mar 9, 2020 at 9:32 AM Chunyan Zhang <zhang.lyra@xxxxxxxxx> wrote: > > On Mon, 9 Mar 2020 at 16:03, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > > On Thu, Mar 5, 2020 at 11:33 AM Chunyan Zhang <zhang.lyra@xxxxxxxxx> wrote: > > > > From: Chunyan Zhang <chunyan.zhang@xxxxxxxxxx> > > > > > > > > The default value of Kconfig for almost all sprd drivers are the same with > > > > ARCH_SPRD, making these drivers built as modules as default would be easier > > > > if we can set ARCH_SPRD as 'm', so this patch change ARCH_SPRD to tristate. > > > > > > > > Signed-off-by: Chunyan Zhang <chunyan.zhang@xxxxxxxxxx> > > > > > > Can you actually boot a kernel on a Spreadtrum platform when all platform > > > and driver support is modular? > > > > Yes, even if all drivers are modular. > > Cool. No hard dependencies on e.g. regulators that are turned off when > unused? > > > But I hope serial can be builtin, then I can have a console to see > > kernel output before loading modules. > > No dependency on the clock driver? > Oh, I see you have a hack in the serial driver, to assume default > values when the serial port's parent clock is not found. That may > limit use of the other serial ports, depending on the actual serial > hardware. > And on Sharkl64, the serial port's clock is a fixed-clock anyway, so > you don't even need the hack. > > But in general you cannot rely on that, especially if your SoC has clock > and/or power domains. > > BTW, what about the watchdog driver? That one does need a clock, and > loading it too late will reboot your system. > > > Also, this's what Google GKI [1] asked :) > > > > Regards, > > Chunyan > > > > [1] https://arstechnica.com/gadgets/2019/11/google-outlines-plans-for-mainline-linux-kernel-support-in-android/ > > Let's see how having everything modular works out on an SoC where all > hardware is part of a clock and power domain. I'm curious, are there any problems that we should be aware of? We know about the regulator sync state and consumer-supplier dependencies. [1] (Adding Saravana inline) Thanks, - ssp
