Re: framebuffer console on old ATI

[Riccardo Mottola <riccardo.mottola%libero.it@localhost>]

Hi John

sorry for the late reply... needed some NetBSD hack time
to find to patch and recompile the kernel.

John D. Baker wrote:
> On Tue, 7 May 2024, Riccardo Mottola wrote:
> 

> That looks like the same description of the radeon device in my T42
> ThinkPad:

IN some sense the T43 is successor of the T30... I'd expect yours to be
a little bit newer. But all these R/RV/RS revisions are confusing.




> (radeondrm0 is the legacy UMS "radeondrm* at drm?" device)
> 
> As an R*200 device, it is not matched by the DRM2 code in NetBSD.
> 
>> Since I am endeavouring in compiling a kernel, I might try enabling it,
>> if you tell me how. Just as a test, maybe magic happens.
> 
> The following patch (against -current from about 4 years ago) will
> enable matching R100/R200 devices:
> 
> 
> +Index: sys/external/bsd/drm2/radeon/radeon_pci.c
> +===================================================================
> +RCS file: /cvsroot/src/sys/external/bsd/drm2/radeon/radeon_pci.c,v
> +retrieving revision 1.14
> +diff -u -p -r1.14 radeon_pci.c
> +--- sys/external/bsd/drm2/radeon/radeon_pci.c	24 Jan 2020 11:44:27 -0000	1.14
> ++++ sys/external/bsd/drm2/radeon/radeon_pci.c	28 May 2020 23:49:44 -0000
> +@@ -126,7 +126,7 @@ extern const struct pci_device_id *const
> + extern const size_t radeon_n_device_ids;
> + 
> + /* Set this to false if you want to match R100/R200 */
> +-bool radeon_pci_ignore_r100_r200 = true;
> ++bool radeon_pci_ignore_r100_r200 = false;
> + 
> + static bool
> + radeon_pci_lookup(const struct pci_attach_args *pa, unsigned long *flags)
> 

This patch was a little hard to read, looks like a patch of a patch? But
the core is to swap true to false. in a match.
I did...
However, it does not work properly. During boot, when FB should attach,
the whole scren displays garbage.
It is not hi-res garbage, the screen still looks like being in VGA
resolution and contains just blocks of green and white stripes (as of
the console dmesg).

So indeed the code does not seem to handle my RS250 without further tweaks!


> 
> I really don't know.  My understanding is that on OpenBSD and various
> Penguin-OSes, these older ATI devices work fine.

Indeed and we shouldn't be "of less" :) :)

> I saw your message about trying "radeonfb* at pci?" in your kernel config.

For that I am just trying Michael's suggestions, after having enabled
again radeon_pci_ignore_r100_r200


Will report there.
For most users it would be probably to have drm working... but let's
start getting a framebuffer at all.

Riccardo