On Tue, Jun 5, 2018 at 10:31 AM, Darren Hart <dvhart@xxxxxxxxxxxxx> wrote: > On Mon, Jun 04, 2018 at 04:23:04PM +0200, Hans de Goede wrote: >> Hi, >> >> On 04-06-18 15:51, Daniel Drake wrote: >> > On Mon, Jun 4, 2018 at 7:22 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: >> > > Is this really a case of the hardware itself processing the >> > > keypress and then changing the brightness *itself* ? >> > > >> > > From the "[PATCH 2/2] platform/x86: asus-wmi: Add keyboard backlight >> > > toggle support" patch I get the impression that the driver is >> > > modifying the brightness from within the kernel rather then the >> > > keyboard controller are ACPI embeddec-controller doing it itself. >> > > >> > > If that is the case then the right fix is for the driver to stop >> > > mucking with the brighness itself, it should simply report the >> > > right keyboard events and export a led interface and then userspace >> > > will do the right thing (and be able to offer flexible policies >> > > to the user). >> > >> > Before this modification, the driver reports the brightness keypresses >> > to userspace and then userspace can respond by changing the brightness >> > level, as you describe. >> > >> > You are right in that the hardware doesn't change the brightness >> > directly itself, which is the normal usage of LED_BRIGHT_HW_CHANGED. >> > >> > However this approach was suggested by Benjamin Berg and Bastien >> > Nocera in the thread: Re: [PATCH v2] platform/x86: asus-wmi: Add >> > keyboard backlight toggle support >> > https://marc.info/?l=linux-kernel&m=152639169210655&w=2 >> > >> > The issue is that we need to support a new "keyboard backlight >> > brightness cycle" key (in the patch that follows this one) which >> > doesn't fit into any definitions of keys recognised by the kernel and >> > likewise there's no userspace code to handle it. >> > >> > If preferred we could leave the standard brightness keys behaving as >> > they are (input events) and make the new special key type directly >> > handled by the kernel? >> >> I'm sorry that Benjamin and Bastien steered you in this direction, >> IMHO none of it should be handled in the kernel. >> >> Anytime any sort of input is directly responded to by the kernel >> it is a huge PITA to deal with from userspace. The kernel will have >> a simplistic implementation which almost always is wrong. >> >> Benjamin, remember the pain we went through with rfkill hotkey >> presses being handled in the kernel ? >> >> And then there is the whole acpi_video.brightness_switch_enabled >> debacle, which is an option which defaults to true which causes >> the kernel to handle LCD brightness key presses, which all distros >> have been patching to default to off for ages. >> >> To give a concrete example, we may want to implement software >> dimming / auto-off of the kbd backlight when the no keys are >> touched for x seconds. This would seriously get in the way of that. >> >> So sorry, but NACK to this series. > > So if instead of modifying the LED value, the kernel platform drivers > converted the TOGGLE into a cycle even by converting to an UP event > based on awareness of the plaform specific max value and the read > current value, leaving userspace to act on the TOGGLE/UP events - would > that be preferable? > > Something like: > > if (code == TOGGLE && ledval < ledmax) > code = UP; > > sparse_keymap_report_event(..., code, ...) > > } > -- > Darren Hart > VMware Open Source Technology Center That's what I was trying to do in [PATCH v2] platform/x86: asus-wmi: Add keyboard backlight toggle support. However, that brought another problem discussed in the thread. https://marc.info/?l=linux-kernel&m=152639169210655&w=2 So I moved the brightness change in the driver without passing to userspace. Per Hans, seems there're some other concerns and I also wonder if the TOGGLE event happens in ASUS HID (asus-hid.c) which also convert and pass the keycode to userspace but no TOGGLE key support yet What should we do then?
