Why can’t I get easy hardware

When I bought my Latitude I complained that it seemed to me more and more like a mistake — until the kernel started shipping with the correct (and fixed) drivers, so the things that originally didn’t work right (the SD card reader, the shutdown process, the touchpad, …) started working quite nicely. As of September 2011 (one year and a quarter after I bought it), between Linux and firmware updates from Dell and Broadcom, the laptop worked almost completely — only missing par still is the fingerprint reader, which I really don’t care that much about.

Recently, you probably have seen my UEFI post where I complained that I couldn’t install Sabayon on the new Zenbook (which is where I’m writing from, right now, on Gentoo). Well, that wasn’t the only problem I got with this laptop, and I should really start reporting issues to the kernel itself, but in the mean time let me write down some notes here.

First off, the keyboard backlight is nice and all, but I don’t need it – I learnt to touch-type when I was eight – so it would just be a battery waste of time. While the keys are reported correctly, and upower supports setting the backlight, at least the stable version of KDE doesn’t seem to support the backlight setting. I should ask my KDE friends if they can point me in the right direction. Another interesting point is that while the backlight is turned on at boot, it’s off after suspension — which is probably a bug in the kernel, but it’s working fine for me.

Speaking about things not turning back on after suspension, the WLAN LED on the keyboard is not turning on, at resume. And related to that, the rfkill key doesn’t seem to work that well either. It’s not a big deal but it’s a bit bothersome, especially since I would like to turn off the bluetooth adapter only (and since that’s supposedly hardware-controlled, it should get me some more battery life).

The monitor’s backlight is even more troublesome: first problem is deciding who should be handling it — i’s either the ACPI video driver (by default), the ASUS WMI driver, or the Intel driver — of the three, the only one that make it work is the Intel driver, and I’m not even sure if that’s actually controlling the backlight or just the tint on the screen, even though, when set to zero, it turns the screen OFF, not just display it as black. It does make it bearable though.

The brightness keys on the keyboard don’t work, by the way, nor does the one that should turn on and off the light sensor — the latter, isn’t even recognized as a key by the asus-wmi driver, and I can’t be sure of the correct device ID that I should use to turn on/off said light sensor. After I hacked the driver to not expose either the ACPI or the WMI brightness interfaces, I’m able to set the brightness from KDE at least — but it does not seem to stick, if I take it down, and after some time it starts and gets back to the maximum (when the power is connected, at least).

And finally, there is the matter of the SD card reader. Yesterday I went to use it, and I found out that … it didn’t work. Even though it’s an USB device, it’s not mass-storage — it’s a Realtek USB MMC device, which does not use the standard USB interface for MMC readers at all! After some googling around, I found that Realtek actually released a driver for that, and after some more digging I found out that said driver is currently (3.7) in the staging drivers’ tree as a virtual SCSI driver (with its own MMC stack) — together with a PCI-E peer, which has been already rewritten for the next release (3.8) as three split drivers (a MFD base, a MMC driver, and a MemoryStick driver). I tried looking into working on porting the USB one as well, but it seems to be a lot of work, and Realtek (or rather, Realsil) seems to be already working on it to port it to the real kernel, so it might be worth waiting.

To be fair what dropped away the idea from me of working on the SD card driver is that to have an idea of what’s going on I have to run 3.8 — and at RC1 panics as soon as I re-connect the power cable. So even though I would like to find enough time to work on some kernel code, this is unlikely to happen now. I guess I’ll spend the next three days working on Gentoo bugs, then I have a customer to take care of, so this is just going to be dropped off my list quite quickly.

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