[PATCH/RFC 0/3] Atari DRM driver
Eero Tamminen
oak at helsinkinet.fi
Tue May 27 22:47:20 UTC 2025
Hi Geert,
On 25.5.2025 15.05, Geert Uytterhoeven wrote:
> On Thu, 22 May 2025 at 00:56, Eero Tamminen <oak at helsinkinet.fi> wrote:
>> On 21.5.2025 10.06, Geert Uytterhoeven wrote:
>>> I do keep it up-to-date locally, so I could provide these changes,
>>> if you are interested.
>>
>> Yes, please! (see below)
>
> Sorry for taking so long:
> https://web.git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k.git/log/?h=atari-drm-wip-rebasing
Thanks!
I did boot testing on Hatari emulator with a minimal kernel config
having atari_drm enabled, atafb disabled, FB & boot logo enabled.
Under Falcon emulation:
- RGB/VGA => works fine
- Mono monitor => panic
"Kernel panic - not syncing: can't set default video mode"
Under TT emulation:
- RGB/VGA => boots, but console is black[1] (palette issue?)
- Mono monitor => looks OKish[2], but has constant warnings:
-----------------------------------
WARNING: CPU: 0 PID: 1 at drivers/gpu/drm/drm_atomic_helper.c:1720
drm_atomic_helper_wait_for_vblanks+0x1a0/0x1ee
[CRTC:35:crtc-0] vblank wait timed out
-----------------------------------
Under 030 ST/STe emulation:
- RGB/VGA => boots, but console is black (palette issue?)
- Mono monitor => looks OK, but has constant slowpath warnings with:
"[CRTC:35:crtc-0] vblank wait timed out"
=> Any advice on the issues?
[1] Black when booted with (Hatari) LILO, all white when booted with
"bootstra.prg", meaning from TOS.
[2] Mono colors are black on white instead of vice verse, e.g. boot logo
colors are obviously inversed.
Note: the functional differences between ST, STE, TT and Falcon are all
accurately emulated in Hatari.
- Eero
PS. I also profiled where most of time goes from "atari-drm" probing,
until boot reaches user space. On a minimal -Os built kernel, running
on (emulated) 32Mhz 030 Falcon, in the default 640x480 at 4 resolution:
----------------------------------------------------------------
Time spent in profile = 15.29712s.
...
Used cycles:
22.37% 22.42% 25.35% _transp
19.15% 19.19% 46.82% atari_drm_fb_blit_rect.isra.0
8.09% 8.09% 13.80% sys_copyarea
3.94% 3.95% 6.23% sys_imageblit
3.69% 3.69% 3.69% fb_copy_offset.isra.0
2.12% 2.13% 2.41% atari_scsi_falcon_reg_read
2.03% 2.03% 2.03% fb_address_forward
1.85% 1.85% 17.98% fbcon_redraw_blit.constprop.0
1.81% 1.81% 2.04% atari_keyb_init
1.78% 1.78% 1.98% fb_reverse_long
1.58% 1.58% 1.90% arch_cpu_idle
1.05% memcpy
0.95% memset
...
----------------------------------------------------------------
=> atari-drm blitting takes half the time during boot.
Building kernel with -O2, changes above rather radically, both
time-wise, and where that time goes:
----------------------------------------------------------------
Time spent in profile = 6.54049s.
...
Used cycles:
17.61% 17.61% 17.61% sys_copyarea
11.18% 11.18% 13.11% arch_cpu_idle
7.53% 7.55% 8.45% atari_drm_fb_blit_rect.isra.0
4.26% 4.27% 4.76% atari_keyb_init
2.70% 2.70% 2.93% atari_scsi_falcon_reg_read
2.45% 2.45% 23.81% fbcon_redraw_blit.constprop.0
2.35% 2.35% 2.48% sys_imageblit
2.12% 2.12% 5.89% atari_floppy_init
1.97% memset
1.31% memcpy
...
Instruction cache misses:
27.14% 27.14% 27.14% sys_copyarea
3.77% 3.77% 4.05% atari_scsi_falcon_reg_read
...
Data cache hits:
63.55% 63.55% 63.67% atari_keyb_init
7.61% 7.62% 7.84% atari_drm_fb_blit_rect.isra.0
3.86% 3.86% 3.86% sys_copyarea <= not much hits for copying
...
----------------------------------------------------------------
However, -O2 build has the downside that the resulting kernel Oopses
once it reaches user-space, if 030 data cache emulation is enabled:
----------------------------------------------------------------
Run /init as init process
...
Instruction fault at 0x0041a256
BAD KERNEL BUSERR
Oops: 00000000
PC: [<0041a256>] __generic_copy_from_user+0x1e/0x46
SR: 2200 SP: (ptrval) a2: 011fe590
d0: 00000005 d1: 00000000 d2: 00000003 d3: 00000003
d4: 00000008 d5: 00000000 a0: eff70720 a1: 01225f9c
Process init (pid: 32, task=(ptrval))
Frame format=B ssw=5066 isc=5380 isb=66f6 daddr=eff7071c dobuf=00000000
baddr=eff7071c dibuf=eff7071c ver=0
Stack from 01225f78:
...
Call Trace: [<000409b0>] sys_rt_sigaction+0x32/0xc8
[<00005062>] req_need_defer+0x2a/0x3a
[<0000a4ca>] syscall+0x8/0xc
Code: 7403 c282 206e 000c 226e 0008 4a80 670a <0e98> 2000 22c2 5380 66f6
0801 0001 6706 0e58 2000 32c2 0801 0000 6706 0e18 2000
Disabling lock debugging due to kernel taint
Instruction fault at 0x00088ada
BAD KERNEL BUSERR
Oops: 00000000
PC: [<00088ada>] exit_robust_list+0x12/0xee
SR: 2200 SP: (ptrval) a2: 011fe590
d0: 00000000 d1: 00000000 d2: 011fe94e d3: 000000ff
d4: 00000000 d5: 00000000 a0: 011fe590 a1: 011e2b90
Process init (pid: 32, task=(ptrval))
Frame format=B ssw=5066 isc=660a isb=0eab daddr=801a206c dobuf=011fe94e
baddr=801a206c dibuf=801a206c ver=0
Stack from 01225dc8:
....
Call Trace: [<00003730>] _printk+0x0/0x16
[<000896ce>] futex_exit_release+0x9e/0xb8
[<00030186>] exit_mm_release+0x12/0x28
[<00034612>] do_exit+0x178/0x96e
[<00002200>] show_stack+0xce/0xf4
[<000691da>] vprintk+0x12/0x16
[<00034e84>] make_task_dead+0x7c/0x172
[<00005066>] req_need_defer+0x2e/0x3a
[<00003730>] _printk+0x0/0x16
[<0000d514>] die_if_kernel+0x0/0x22
[<0000d536>] trap_c+0x0/0x24c
[<0000ddaa>] buserr_c+0x628/0x756
[<0000a3f0>] buserr+0x20/0x28
[<00005066>] req_need_defer+0x2e/0x3a
[<0004097e>] sys_rt_sigaction+0x0/0xc8
[<00020007>] _FP_CALL_TOP+0x48e5/0xd512
[<00002000>] _start+0x0/0x6
[<000409b0>] sys_rt_sigaction+0x32/0xc8
[<00005062>] req_need_defer+0x2a/0x3a
[<0000a4ca>] syscall+0x8/0xc
----------------------------------------------------------------
My GCC is 12.2 in Debian bookworm, and "/init" is shell script run with
static Debian Busybox, to mount virtual file systems:
https://github.com/hatari/hatari/blob/main/tools/linux/init.sh
On an small system image built and used as documented here:
https://github.com/hatari/hatari/blob/main/doc/m68k-linux.txt
-------------- next part --------------
A non-text attachment was scrubbed...
Name: atari-drm-callgraph.png
Type: image/png
Size: 46420 bytes
Desc: not available
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20250528/62065038/attachment-0001.png>
More information about the dri-devel
mailing list