On Wed, 13 Dec 2023 at 23:55, Elliott Mitchell <ehem+open...@m5p.com> wrote: > > On Wed, Dec 13, 2023 at 01:59:07PM +0100, Martin Schiller wrote: > > On 2023-12-13 02:45, Elliott Mitchell wrote: > > > > > > No idea, I wasn't able to find very much information when I looked at > > > this. > > > > > > I did find: > > > https://lists.openwrt.org/pipermail/openwrt-devel/2018-August/019479.html > > > > > > This doesn't tell me what platform Martin Schiller was trying for. > > > 17f30bfcf7 makes me suspect Martin Schiller was simply trying to do > > > this > > > to all x86 platforms and didn't realize geode was a specialized target. > > > > > > Alternatively Martin Schiller may have been trying to use a MCP23S08 on > > > a > > > Geode processor. Unfortunately using CONFIG_X86_INTEL_LPSS is a > > > bizzare > > > choice since CONFIG_X86_AMD_PLATFORM_DEVICE has fewer side-effects and > > > then current Geodes were AMD processors. > > > > > > With sparse information the former is my present belief. Is anyone > > > reading this list using a Geode processor with a MCP23S08? Otherwise > > > my > > > present belief is only people with Intel x86 processors are interested > > > in > > > the MCP23S08. > > > The problem was and is that the PINCTRL subsystem can only be used on > > x86 > > platforms if either X86_INTEL_LPSS or X86_AMD_PLATFORM_DEVICE is > > activated. > > I no longer know why I chose the former at the time. > > Which leaves me suspecting the reason was you had a computer with a > processor from Intel. > > > X86_AMD_PLATFORM_DEVICE is now activated for x86/generic and x86/64. > > > > From my point of view, we can deactivate X86_INTEL_LPSS if no one else > > need it. > > Seeing how Xiaopo Zhang submitted patches to enable them, I assume at > least 1 other person used them on x86/64 at some point. > > What situation/hardware were YOU using CONFIG_PINCTRL for? > > Were you using CONFIG_PINCTRL on a desktop which had an Intel processor? > > Were you using CONFIG_PINCTRL on a system which had a Geode processor? > > If someone out there is actively using CONFIG_PINCTRL on a system with a > Geode processor, I would disable CONFIG_X86_INTEL_LPSS and enable > CONFIG_X86_AMD_PLATFORM_DEVICE. The reason is both options select > CONFIG_COMMON_CLK and CONFIG_PINCTRL, but CONFIG_X86_INTEL_LPSS > additionally selects CONFIG_IOSF_MBI (less bloat). > > If my belief no one is using CONFIG_PINCTRL on a Geode platform is > correct, then the original patch is correct. From examination of the > Linux kernel source, I believe none of Geode's normal peripherals go > through the PINCTRL subsystem. > > Problem is too few people have systems with Geode processors in use, so > support is difficult.
Here, I'll do some research work for you: 1. To select the MCP23S08 driver you need to have PINCTRL enabled since 4.13 (see also [1]). 2. At time of Linux 4.14, PINCTRL was a non user-selectable symbol [2]. 3. Therefore, a driver selecting this was needed in the kernel config (it didn't matter which one). 4. In a later Linux release (4.15), PINCTRL was changed to a user-selectable symbol [3]. 5. Therefore, the intel driver is not needed anymore, but PINCTRL needs to stay enabled. And since we build the MCP23S08 driver as a module/kmod package, it really doesn't matter if this driver is used or not; having it available makes sure it can be installed if needed. Micromanaging which drivers/modules should be available to which (sub-)targets really doesn't provide much benefit compared to the effort for it, unless the driver/module is one specific to the hardware targeted by the (sub)target. And as you said, too few people have systems with Geode processors, so getting a definite answer there is difficult. Best Regards, Jonas [1] https://github.com/openwrt/openwrt/commit/a904003b9b5fe2744ee5d5d8718c54d001f1c93e [2] https://elixir.bootlin.com/linux/v4.14.333/source/drivers/pinctrl/Kconfig#L5 [3] https://github.com/torvalds/linux/commit/d219b924611a5cceb17cc6b9a8dd103ab9668c94 _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
