Re: [PATCH v2 00/17] Modularizing Versatile Express

From: Daniel Thompson <daniel.thompson@linaro.org>
To: Rob Herring <robh@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	Liviu Dudau <liviu.dudau@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-pm@vger.kernel.org, Stephen Boyd <sboyd@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Kevin Brodsky <Kevin.Brodsky@arm.com>,
	Sebastian Reichel <sre@kernel.org>, Will Deacon <will@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Lee Jones <lee.jones@linaro.org>,
	linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 00/17] Modularizing Versatile Express
Date: Wed, 17 Jun 2020 16:08:50 +0100	[thread overview]
Message-ID: <20200617150850.t23gwj3p2qnduq2a@holly.lan> (raw)
In-Reply-To: <20200429205825.10604-1-robh@kernel.org>

On Wed, Apr 29, 2020 at 03:58:09PM -0500, Rob Herring wrote:
> This series enables building various Versatile Express platform drivers
> as modules. The primary target is the Fast Model FVP which is supported
> in Android. As Android is moving towards their GKI, or generic kernel,
> the hardware support has to be in modules. Currently ARCH_VEXPRESS
> enables several built-in only drivers. Some of these are needed, but
> some are only needed for older 32-bit VExpress platforms and can just
> be disabled. For FVP, the pl111 display driver is needed. The pl111
> driver depends on vexpress-osc clocks which had a dependency chain of
> vexpress-config --> vexpress-syscfg --> vexpress-sysreg. These
> components relied on fixed initcall ordering and didn't support deferred
> probe which would have complicated making them modules. All these levels
> of abstraction are needlessly complicated, so this series simplifies
> things a bit by merging the vexpress-config and vexpress-syscfg
> functionality.
> 
> There's a couple of other pieces to this which I've sent out separately
> as they don't have dependencies with this series. The cross subsystem
> dependencies in this series are mainly the ordering of enabling drivers
> as modules.

This series results in the vexpress-a15 console not coming up until very
late in the boot process because the console arch_initcall() ends up
being deferred because it's dependencies are no longer use
core_initcall() to ensure they get in first.

Is there a problem registering vexpress-osc, vexpress-sysreg and
vexpress-config as core_initcall's so the console behaves nicely
when they are all compiled as built-ins?

Daniel.

> 
> A complete git branch is here[1]. Tested on Fast Model FVP Rev C.
> 
> v2:
> The major change is a boot fix for 32-bit VExpress platforms with patch 3.
> I also dropped 'power/reset: vexpress: Support building as a module' as it
> was incomplete and not needed for this series.
> 
> Rob
> 
> [1] git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git vexpress-modules-v4
> 
> Rob Herring (16):
>   ARM: vexpress: Move vexpress_flags_set() into arch code
>   arm64: vexpress: Don't select CONFIG_POWER_RESET_VEXPRESS
>   amba: Retry adding deferred devices at late_initcall
>   clk: versatile: Rework kconfig structure
>   clk: versatile: Only enable SP810 on 32-bit by default
>   clk: vexpress-osc: Use the devres clock API variants
>   clk: vexpress-osc: Support building as a module
>   mfd: vexpress-sysreg: Drop selecting CONFIG_CLKSRC_MMIO
>   mfd: vexpress-sysreg: Drop unused syscon child devices
>   mfd: vexpress-sysreg: Use devres API variants
>   mfd: vexpress-sysreg: Support building as a module
>   bus: vexpress-config: Merge vexpress-syscfg into vexpress-config
>   bus: vexpress-config: simplify config bus probing
>   vexpress: Move setting master site to vexpress-config bus
>   bus: vexpress-config: Support building as module
>   ARM: vexpress: Don't select VEXPRESS_CONFIG
> 
>  arch/arm/mach-integrator/Kconfig         |   1 -
>  arch/arm/mach-realview/Kconfig           |   1 -
>  arch/arm/mach-versatile/Kconfig          |   1 -
>  arch/arm/mach-vexpress/Kconfig           |   4 -
>  arch/arm/mach-vexpress/core.h            |   1 +
>  arch/arm/mach-vexpress/dcscb.c           |   1 +
>  arch/arm/mach-vexpress/v2m.c             |  23 ++
>  arch/arm64/Kconfig.platforms             |   3 -
>  drivers/amba/bus.c                       |  14 +-
>  drivers/bus/Kconfig                      |   2 +-
>  drivers/bus/vexpress-config.c            | 354 ++++++++++++++++++-----
>  drivers/clk/Makefile                     |   2 +-
>  drivers/clk/versatile/Kconfig            |  24 +-
>  drivers/clk/versatile/clk-vexpress-osc.c |  20 +-
>  drivers/mfd/Kconfig                      |   5 +-
>  drivers/mfd/vexpress-sysreg.c            |  99 +------
>  drivers/misc/Kconfig                     |   9 -
>  drivers/misc/Makefile                    |   1 -
>  drivers/misc/vexpress-syscfg.c           | 280 ------------------
>  include/linux/vexpress.h                 |  30 --
>  20 files changed, 354 insertions(+), 521 deletions(-)
>  delete mode 100644 drivers/misc/vexpress-syscfg.c
> 
> 
> base-commit: 8f3d9f354286745c751374f5f1fcafee6b3f3136
> ---
> 2.20.1