re: kern/51339 (No drmkms available for Radeon R7 250)

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR kern/51339; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: riastradh%NetBSD.org@localhost, netbsd-bugs%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    dholland%NetBSD.org@localhost, adrien_fernandes2%hotmail.com@localhost
Subject: re: kern/51339 (No drmkms available for Radeon R7 250)
Date: Tue, 30 Aug 2016 10:58:09 +1000

 FWIW, the ati driver disables all acceleration on GCN rev1 chipsets
 and the R7 250 is one of these.
 
 i do have X sort of working with an R7 240 which seems very similar
 to the 250, except slower and fewer shader + texture cores, but there
 is no acceleration.  this is with native xorg-server 1.18 and amd64.
 
 from xf86-video-ati's src/radeon_kms.c:
 
     833     if (info->ChipFamily >=3D CHIP_FAMILY_TAHITI) {
     834         goto shadowfb;
 
     819 shadowfb:
     820         info->r600_shadow_fb =3D TRUE;
 
    1627     info->directRenderingEnabled =3D FALSE;
    1628     if (info->r600_shadow_fb =3D=3D FALSE)
    1629         info->directRenderingEnabled =3D radeon_dri2_screen_init(p=
 Screen);
 
 and from radeon_probe.h:
 
     110     CHIP_FAMILY_TAHITI,
     111     CHIP_FAMILY_PITCAIRN,
     112     CHIP_FAMILY_VERDE,
     113     CHIP_FAMILY_OLAND,
 
 (both the 240 and 250 are OLAND generation.)
 
 i don't know why it has to use shadowfb or why this means no DRI,
 but that's what i see in the code of xf86-video-ati 7.7.0.
 
 
 .mrg.