Radeon vs. RadeonHD Drivers In H1'08

[sreyan]

For those in the know, will the AtomBios work with cards that have firmware for macs?

I have a 2600xt mac card that works perfectly well with the latest versions of RadeonHD.

I'd appreciate clarification on the difference between the firmware/bios in the mac cards and also if atom bios would/should/does support it.

Regards,
-Sreyan

[bridgman]

Yes, the same AtomBIOS calls are used by the Windows driver which runs on the Mac. I think you need to be running under BootCamp to expose the firmware today.

[bridgman]

while ati/radeon has serious problems with TexturedVideo and 2D acceleration for me

It's probably worth mentioning that right now most of the new acceleration work has to be done in radeon because the DRI support is not yet available in radeonhd. Once DRI support and DRM/CP functionality become available in radeonhd, you can look forward to being able to use brand new acceleration code with radeonhd as well

[agd5f]

The ati/radeon devs are doing a great job, but in my opinion, RadeonHD is the way to go if you have R500+ hardware... at this early state I found RadeonHD to be rockstable already while ati/radeon has serious problems with TexturedVideo and 2D acceleration for me, and I think the RadeonHD driver will take the lead in performance and stability later this year...

Unfortunately, acceleration is the hardest thing to get working correctly in a video driver, especially the 3D engine (used by textured video and EXA render accel). Once radeonhd gets similar acceleration features, they will be in the same boat.

[agd5f]

For those in the know, will the AtomBios work with cards that have firmware for macs?

I have a 2600xt mac card that works perfectly well with the latest versions of RadeonHD.

I'd appreciate clarification on the difference between the firmware/bios in the mac cards and also if atom bios would/should/does support it.

Depends on the card. If it includes atom tables you should be fine. If not, you'll have to use bootcamp or we would need to include atom tables for your card.

[libv]

Here's the issue -- only the modesetting hardware changed between 4xx and 5xx. The acceleration hardware is largely unchanged, so the same code generally runs on both 3xx/4xx and 5xx parts.

With an emphasis on "generally".

Sure, but we already provided the documentation

Partly. As far as i can remember, none of the PLL registers have ever been made public. Also, with both drivers now supporting RV620/635, the documentation for that still is not available. Since radeon fully depends on atombios (but hasn't much of a clue of what happens underneath), is there no more need for this information now?

We are providing complete documentation for what the registers do, and in some cases are creating new docs which explain how the pieces fit together. What we were hoping not to have to provide is the "set this register to 0x7... set that register to 0x0015fe2" level of detail since that was already coded and heavily tested in AtomBIOS.

So AtomBIOS means that you do not ever have to bother with providing actual programming information?

One of the design criteria for AtomBIOS was the ability for the driver to over-ride any table with a newer version if required. We have been using AtomBIOS for the Windows drivers for a few years now and have never had to patch a table, but the mechanism is there.

Given that ATI doesn't want people to flash the BIOSes of their cards, it is rather hard to get patched tables out to people. In that light, it is probably just Not Done to patch any tables.

Luckily the hardware is quite resilient, and i'm sure the windows/fglrx driver are full of workarounds like this: http://gitweb.freedesktop.org/?p=xor...t;h=10e7636c02

Actually, that's not the case with AtomBIOS. We don't restrict you to specific modes. There is a traditional VBE / BIOS layer running on top of AtomBIOS which does have a fixed mode table, but that only affects VBE calls.

It does restrict things which real code would not restrict. The choice between PAL or NTSC is largely dependant on what is available in AtomBIOS.

[agd5f]

Luckily the hardware is quite resilient, and i'm sure the windows/fglrx driver are full of workarounds like this: http://gitweb.freedesktop.org/?p=xor...t;h=10e7636c02

This is to workaround the fact that we only use atom for external tmds chips on r4xx cards, the rest uses the old code.

[libv]

Unfortunately, acceleration is the hardest thing to get working correctly in a video driver, especially the 3D engine (used by textured video and EXA render accel). Once radeonhd gets similar acceleration features, they will be in the same boat.

This is quite wrong. Modesetting always has been and always will be the single hardest thing to get right. With modesetting the demands and varying configurations are endless.

When acceleration works on one close enough related family of hardware, it will pretty much work everywhere. The user will not go around and suddenly change the whole layout there.

[libv]

This is to workaround the fact that we only use atom for external tmds chips on r4xx cards, the rest uses the old code.

So you're not using atombios to the full extent possible there? Just for those bits where you cannot be bothered?

[ethana2]

Look at the benchmark comparison between them on phoronix, pick the fastest driver for the card, stabilize it, and ship it.

Oh wait... don't tell me you didn't take bechmarks here.. I'm not seeing them. Am I missing something?