On Fri, Apr 19, 2024 at 10:35 AM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote:
> Add support for damage handling and deferred I/O to fbdev-dma. This
> enables fbdev-dma to support all DMA-memory-based DRM drivers, even
> such with a dirty callback in their framebuffers.
>
> The patch adds the code for deferred I/O and also sets a dedicated
> helper for struct fb_ops.fb_mmap that support coherent mappings.
>
> v3:
> - init fb_ops with FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS() (Javier)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
For some reason this makes the Versatile Express crash in QEMU
(I can retest on real hardware if necessary):
8<--- cut here ---
Unable to handle kernel paging request at virtual address 18095000 when write
[18095000] *pgd=00000000
Internal error: Oops: 805 [#1] SMP ARM
CPU: 0 PID: 75 Comm: S08_ledflash Not tainted 6.9.0-rc6+ #44
Hardware name: ARM-Versatile Express
PC is at mmioset+0x34/0xac
LR is at 0x0
pc : [<809c2a54>] lr : [<00000000>] psr: 20000013
sp : f8dddc38 ip : 18095000 fp : 00000000
r10: 81109a18 r9 : 81238b04 r8 : 00000000
r7 : 00440dc0 r6 : ed4f32a0 r5 : ed4f32a0 r4 : 00000001
r3 : 00000000 r2 : 00000fc0 r1 : 00000000 r0 : 18095000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 81d6406a DAC: 00000051
Register r0 information: non-paged memory
Register r1 information: NULL pointer
Register r2 information: non-paged memory
Register r3 information: NULL pointer
Register r4 information: non-paged memory
Register r5 information: non-slab/vmalloc memory
Register r6 information: non-slab/vmalloc memory
Register r7 information: non-paged memory
Register r8 information: NULL pointer
Register r9 information: non-slab/vmalloc memory
Register r10 information: non-slab/vmalloc memory
Register r11 information: NULL pointer
Register r12 information: non-paged memory
Process S08_ledflash (pid: 75, stack limit = 0x(ptrval))
Stack: (0xf8dddc38 to 0xf8dde000)
dc20: 00000801 802af888
dc40: 80a0fb80 00440dc0 00000801 811fad80 00000000 f8dddd28 ed4f32a0 811fa680
dc60: 00000000 802b0c30 ee1d2140 ee1d215c 95ff4385 00000001 00000001 00000001
dc80: 00000000 00000000 ffffffff 8196a70b 000000b0 00000064 0000006c 00000000
dca0: 00000001 00000002 00000001 811fa798 00000801 811fa940 80a0fb80 00000cc0
dcc0: 00000001 00000001 00000000 f8dddd28 811fa93c 811fa680 00000002 802b0c30
dce0: ee1d2140 00440dc0 00000000 00000000 00000001 00000000 811fad80 00440dc0
dd00: 00000001 00000000 00000000 83201100 00440dc0 00000000 00000000 802afa18
dd20: 00000bdc 00000bd8 811fad80 00000000 811fad80 00000000 00000000 00000000
dd40: adf00ec5 816d5fa8 816d5fa8 821c3c00 00000000 7ebc2000 7ebe3000 00000000
dd60: f8ddde44 8028cfa0 816d5fa8 8288df50 8169cf00 821c3c00 7ebc2000 7ebe3000
dd80: f8ddde44 8028e1e8 00000001 80bbe932 f8ddde44 f8dddde8 f8ddde44 8288df50
dda0: 83201100 809cf474 f8ddde44 8169cf00 00000020 8169cf94 821c3c94 7ebe3000
ddc0: 7ebe2fff fffffff4 00000000 816d5fa8 821c3c00 8169cf00 81d65fa8 809cdbb0
dde0: 8288df50 81ffa910 7ebe3000 82890b00 00000000 00000000 00000000 00000000
de00: 00000000 00000000 adf00ec5 00000000 00000000 8169cf00 8288df50 83201100
de20: 821c3c00 81ffa910 f8ddde44 8011f6e4 00000000 00000000 821c3c7c 8169cf7c
de40: 83200880 821c3c40 7ebc2000 7ebe2fff 82890b0c 76ea4000 ffffffff 00000000
de60: 00000000 0f000a01 f8ddde68 f8ddde68 adf00ec5 00000000 00000000 00000000
de80: 00000000 01200000 83201100 00000000 00000000 8011e2ac 00000000 83200d7c
dea0: 83201020 83200e70 83200e80 00000000 f8dddf30 83200880 00000000 00000000
dec0: 00000000 00000000 00000000 82182f38 adf00ec5 00000000 01200000 f8dddf30
dee0: 00000000 00000000 00000000 00000078 000cb21c 8011fe24 00000020 00000000
df00: 828a5d80 80a10140 adf00ec5 01200011 00000000 00000000 00000000 f8dddf30
df20: 00000000 00000078 000cb21c 801203d4 01200000 00000000 00000000 76f46468
df40: 00000000 00000000 00000011 00000000 00000000 00000000 00000000 00000000
df60: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
df80: 00000003 adf00ec5 76f46468 00000000 76f468c0 00000078 80100290 83201100
dfa0: 000cb21c 80100060 76f46468 00000000 01200011 00000000 00000000 00000000
dfc0: 76f46468 00000000 76f468c0 00000078 00000000 76e81000 76f46400 000cb21c
dfe0: 00000078 7ebe2938 76e0854d 76dae7e6 20000030 01200011 00000000 00000000
Call trace:
mmioset from prep_new_page+0x160/0x194
prep_new_page from get_page_from_freelist+0x10f4/0x110c
get_page_from_freelist from __alloc_pages+0x15c/0x280
__alloc_pages from __pte_alloc+0x28/0x1bc
__pte_alloc from copy_page_range+0xc10/0xd28
copy_page_range from copy_mm+0x5cc/0x850
copy_mm from copy_process+0x508/0xd8c
copy_process from kernel_clone+0x94/0x338
kernel_clone from sys_clone+0x94/0xb0
sys_clone from ret_fast_syscall+0x0/0x1c
Exception stack(0xf8dddfa8 to 0xf8dddff0)
dfa0: 76f46468 00000000 01200011 00000000 00000000 00000000
dfc0: 76f46468 00000000 76f468c0 00000078 00000000 76e81000 76f46400 000cb21c
dfe0: 00000078 7ebe2938 76e0854d 76dae7e6
Code: e92d4100 e1a08001 e1a0e003 e2522040 (a8ac410a)
---[ end trace 0000000000000000 ]---
I bisected down to this commit and reverting the commit solves the issue.
What is special about the Versatile Express graphics is that it uses a special
dedicated video RAM, looks like this in the device tree
reserved-memory {
#address-cells = <1>;
#size-cells = <1>;
ranges;
/* Chipselect 3 is physically at 0x4c000000 */
vram: vram@4c000000 {
/* 8 MB of designated video RAM */
compatible = "shared-dma-pool";
reg = <0x4c000000 0x00800000>;
no-map;
};
};
(...)
clcd@1f000 {
compatible = "arm,pl111", "arm,primecell";
(...)
memory-region = <&vram>;
This gets picked up in the driver
drivers/gpu/drm/pl111/pl111_drv.c
like this:
ret = of_reserved_mem_device_init(dev);
if (!ret) {
dev_info(dev, "using device-specific reserved memory\n");
priv->use_device_memory = true;
}
Yours,
Linus Walleij
