SimpleDRM Will Likely Be Merged In Linux 3.15
Phoronix: SimpleDRM Will Likely Be Merged In Linux 3.15
Besides going for enabling DRM render-nodes by default, David Herrmann is looking to land a bunch of other DRM patches for the Linux 3.15 kernel...
SimpleDRM was really the missing piece to switch to a full DRM system in case of difficult graphic hardware.
Anyone know if SimpleDRM and xf86-video-modesetting will allow user to set custom resolution for the "framebuffer" and xorg sessions? UMS vesa was too limited in choice of resolutions and vesafb video parameter is broke for quite some years now (I never though of uvesafb as a serious substitute).
Actually I was talking about some hard to solve use cases.
Originally Posted by c117152
Let me explain :
Just a few years ago I was running a small business and all my trainees used diskless Linux desktop. The computer was old even by those days : pentium 4 and so on (I ENJOYED my electrical bills at those times ...), but that was fairly enough for them, CPU speaking, but for the graphic part, that was another story. Actually, some of the graphic cards wasn't properly recognized, and I used every kind of them : ati radeon, ati rage, nvida geforce, ... (I was kind enough to spare them the old savage and cirrus logic adapters ). Anyway, I had to use the vesa driver for some of them but it was a problem with wide resolution (1280x800 for instance), and the result was quite poor.
In the same way, I got stuck with a poor vga= (or sometimes nothing at all) parameter in grub for debuging kernel panics (the lack of serial ports really suxx ), in situation were newer kernel weren't an option (I was using openVZ kernels). And yes I compiling the kernel with the only the required frambuffer device support or KMS when avaliable but I still ran into issues.
And for my personal use, I usually hit some very anoying problem like : that new graphic card has a new GPU which is a slightly revision of the chip and it broke the graphic stake, so I will need to use the splandid vesa driver wich sucks the whole hell on my wide display (and there is no more 4:3 display those days anyway) so I can still use my multi boot setup while waiting for a propper suppot on Linux.
So yeah, a more flexible generic KMS driver and DRM would really help in case nothing else work, at last it would be better that vesafb, efifb, vesa, ...
And no, I don't use nvidia cards since a while now, I don't want to give money to company who agree to such terrible business model, even if that means I am lacking of features (I must say the mess the blower of my HD6870 made without DPM was VERY ANOYING).
@Fresh_meat: Vesa is a generic driver. As such, it can only use resolutions that are in the VBIOS of the GPU. Getting other resolutions requires knowledge of how the GPU's output logic works. This logic is specific to the GPU (for example, look at the Radeon Display Hardware list, more or less every generation of GPUs has a new output engine), and if you add such GPU-specific knowledge to a driver, it's no longer a generic driver. So what you want simply isn't possible, it would defeat the point of having a generic driver.
Well, I far as I remember, my former associate used uvesafb on his 1920p XPS with a dual Geforce setup, and he got a native resolution (of cause no recklocing) despite uvesafb being generic.
Originally Posted by Gusar
If the 1920p resolution was the VBIOS, sure. There's no fixed list of resolutions that are in there, it's different on every GPU. Well, there's the standard vesa resolutions, but GPUs can and do sometimes have additional resolutions specified too, including widescreen ones.
Originally Posted by Fresh_meat
And that where a "SimpleDRM" driver, which actually follows RandR specification can help.
Originally Posted by Gusar
With plain VESA, you usually have to guess a "magic number" for a video mode (or at least pick it from a 10-page long list. As mentionned, GPU can sometime have additional resolutions, and on some graphic cards, this list can get quite long).
then you give that mode number to the vesa driver at boot time, which will switch into this mode, attach a framebuffer to it, and don't touch it any more.
At least as SimpleDRM follows the RandR specifications, it would be possible to use the standard XRandR to set video modes as one likes, and the drivers will abstract all the VESA specifics.
This could be even driven further with some VESA extensions:
- AFAIK (I haven't been directly playing with VESA since my DOS days, a long time ago) there are already VESA extensions to access DDC (and thus get info about the monitor attached).
- perhaps some extensions to help basic functions like mode settings to an arbitrary resolution (AFAIK this doesn't exist yet. Or at least didn't exist in the latest SPEC I've read, but perhaps it has moved on a bit since last time).