Hello there,

i *think* i found a regression (card/system freeze in AGP mode) that must have been in the drm code for quite some time (since the switch to kms drivers) and possibly also the potential solution (re-apply an old patch from pre-kms-days). Affected seem to be older cards (actually, very old cards :-) before R600. I mailed this to the ati driver mailing list, but was told that this is a kernel/drm subject now, so i forward the mail interchange to this list. Details below, one has to start reading from the end upwards to get the chronological order, of course.

Could somebody give me a hint on how to re-apply the old patch or whether the info i found is valid ? The next step i would take is to insert some diagnostic messages in radeon_vram_location (see below) and build a new kernel.

Cheers

Jochen


-------- Original-Nachricht --------
Betreff: Fwd: Fwd: Fwd: Re: regression on RV280 card freeze, patch not applicable any more
Datum: Fri, 25 Oct 2013 15:04:33 +0200
Von: Jochen Rollwagen <joro-2013@t-online.de>
An: xorg-driver-ati@lists.x.org

more info (and possible solution):

void radeon_vram_location in radeon_device.c says

 * Note: GTT start, end, size should be initialized before calling this
 * function on AGP platform.
 *
 * Note: We don't explicitly enforce VRAM start to be aligned on VRAM size,
 * this shouldn't be a problem as we are using the PCI aperture as a reference.
 * Otherwise this would be needed for rv280, all r3xx, and all r4xx, but
 * not IGP.
 *

so does this mean i just have to re-apply the old patch i found ? struct radeon_mc in radeon.h contains aper_base as a member which could be set/aligned to VRAM size using the code snippet below.

Cheers

Jochen


-------- Original-Nachricht --------
Betreff: Fwd: Fwd: Re: regression on RV280 card freeze, patch not applicable any more
Datum: Fri, 25 Oct 2013 11:31:32 +0200
Von: Jochen Rollwagen <joro-2013@t-online.de>
An: xorg-driver-ati@lists.x.org

I've done some more researching and found the following:

- There's another follow-on-patch ("Extend the alignment workaround to post-rv280 chips as well") to the one indicated below (http://cgit.freedesktop.org/~agd5f/xf86-video-ati/commit/?id=b2145aea36bb035bff048366c607b967d70fff49) that applies to not only RV280 but "rv280, all r3xx, and all r4xx, but not IGP".

- the piece of code affected seems to be (IMHO) in drivers/gpu/drm/radeon/: The (Radeon ?) Register RADEON_CONFIG_APER_0_BASE is defined in radeon_reg.h but never used in the driver:

radeon_reg.h:#define RADEON_CONFIG_APER_0_BASE           0x0100

in r100.c there's

static u32 r100_get_accessible_vram(struct radeon_device *rdev)
{
    u32 aper_size;
    u8 byte;

    aper_size = RREG32(RADEON_CONFIG_APER_SIZE);

    /* Set HDP_APER_CNTL only on cards that are known not to be broken,
     * that is has the 2nd generation multifunction PCI interface
     */
    if (rdev->family == CHIP_RV280 ||
        rdev->family >= CHIP_RV350) {
        WREG32_P(RADEON_HOST_PATH_CNTL, RADEON_HDP_APER_CNTL,
               ~RADEON_HDP_APER_CNTL);
        DRM_INFO("Generation 2 PCI interface, using max accessible memory\n");
        return aper_size * 2;
    }

That's the code executed on my machine according to dmesg. Missing (from the original patch, not applicable any more because of driver reorganization) seems to be

CARD32 aper0_base = INREG(RADEON_CONFIG_APER_0_BASE);
aper0_base &= ~(mem_size - 1);
info->mc_fb_location = (aper0_base >> 16);

The patch that seems to have removed/overridden this code is:

http://www.mail-archive.com/dri-devel@lists.sourceforge.net/msg41307.html

According to that patch, it was "booted on PCI r100, PCIE rv370, IGP rs400". So IMHO this could be a classical regression for an AGP RV280 card (like mine) and might explain why PCI mode works. this is Additionally corroborated by this post (http://comments.gmane.org/gmane.comp.freedesktop.xorg/5429):

* The above doesn't necessarily work. For example, I've seen machines * with 128Mb configured as 2x64Mb apertures. I'm now _always_ setting * RADEON_HOST_PATH_CNTL. OUTREGP (RADEON_HOST_PATH_CNTL, RADEON_HDP_APER_CNTL, ~RADEON_HDP_APER_CNTL); (which was previously done only on some chip families).

I _think_ this is not correct on all cards as the apertures may not be configured correctly (and X doesn't set them up neither, if those correspond to the RADEON_CONFIG_APER registers)"

Could a Radeon guru confirm this or am i totally lost?

Cheers

Jochen
-------- Original-Nachricht --------
Betreff: Fwd: Re: regression on RV280 card freeze, patch not applicable any more
Datum: Fri, 18 Oct 2013 15:32:18 +0200
Von: Jochen Rollwagen <joro-2013@t-online.de>
An: xorg-driver-ati@lists.x.org 


sorry about that.

Anyway, i checked drivers/gpu/drm/radeon and 
drivers/char/agp/uninorth-agp.c and can't seem to find the patch 
indicated below. Might it have gone missing :-) ?


Am 08.10.2013 18:41, schrieb Michel Dänzer:
> [ Please always follow up to the mailing list ]
>
> On Die, 2013-10-08 at 14:53 +0200, Jochen Rollwagen wrote:
>> Am 08.10.2013 10:03, schrieb Michel Dänzer:
>>> On Sam, 2013-10-05 at 15:13 +0200, Jochen Rollwagen wrote:
>>>> I’m running a RV280 based Radeon 9200 card (I know, an ancient card)
>>>> in a Mac Mini G4 (powerpc-architecture) with Ubuntu Precise and the
>>>> latest 3.4.64-kernel/ati driver and get lockups when trying to run the
>>>> card in AGP mode (KMS enabled). The lockups happen when resetting the
>>>> card (that’s what I can infer from the oops-screen).
>>> It's the other way around: The kernel radeon driver resets the card to
>>> try and get it running again after a lockup.
>>>
>>>> PCI mode works. After researching I found a old bug that was fixed
>>>> back in 2006 (https://bugs.freedesktop.org/show_bug.cgi?id=6011) that
>>>> looks like the freeze I experience (since PCI mode – which allocates
>>>> 64 MB of memory - works and AGP mode which by default allocates 256 MB
>>>> doesn’t). The card has 64 mb memory.
>>>>
>>>> So the first question is, could this be the problem that causes the
>>>> lockups ?
>>> Not really. The GART and VRAM memory apertures aren't directly related,
>>> and the fix for the bug above should still be incorporated in the
>>> current radeon KMS code.
>>>
>>> Does radeon.agpmode=1 or radeon.agpmode=4 work?
>>>
>> Thank you for your reply. First, none of the agpmodes work, they just
>> take more or less time to lockup the card (1 - slowest, 4 fastest).
>> Secondly, if you write that the fix "should be incorporated in the
>> current code", i'm somewhat lost because it definitely isn't there.
> It's in the kernel now.
>
Well........no. I checked the 3.4.64 kernel sources after my last Mail
and the code isn't in the drivers/gpu/drm/radeon sources. But of course
i might have overlooked something.