At Fri, 13 Apr 2012 11:30:01 -0400, Alex Deucher wrote:
On Fri, Apr 13, 2012 at 11:13 AM, Takashi Iwai tiwai@suse.de wrote:
At Fri, 13 Apr 2012 15:35:04 +0100, Dave Airlie wrote:
I don't think we need to support all wild modes, too. But the _very_ common modes like 1366x768 and 1600x900 should be really supported as default.
You guys still haven't answered the basic question, what HW is this broken?
The reported problem is about HP laptops with i915 driver (no matter chip chip is) and several monitors with resolutions more than the laptop panel.
The LVDS provides only the native resolution (either 1366x768 or 1600x900) and a few other VESA ones (1024x768, 800x600 and 640x480). Meanwhile, the monitor EDID doesn't provide such laptop-native resolutions. Thus, in clone mode, the only possible resolution is 1024x768 or lower. That's the whole problem. It's too low and doesn't match with 16:9 although both laptop and monitor panels are 16:9.
HP wants the clone mode of the laptop-native resolution and/or a higher resolution with the right aspect ratio like 1280x720. Neither work as of now unless you add the extra mode manually.
One thing to be careful of is that some monitors (especially LCD panels) don't like modes that are not in their EDIDs. As such when you try and set them you often get a wonky display or more often a blank screen. We used to add a lot of inferred modes to the mode list in the xserver which resulted in a lot of blank screens when some odd mode was picked as the best match for a cloned display. The "fix" was to only add the inferred modes on analog monitors which were more likely to be able to support them.
Thanks, it's good to know!
Though, I still wonder whether adding inferred modes for 1366x768 or 1600x900 would cause any big problems. On such monitors, 1360x768 or 1440x900 (or 1680x1050) are usually seen in the supported list.
Of course, it's never 100% safe. But not so bad odds?
Takashi