On Wed, 03 Dec 2025 21:03:23 +0800, Xiaolei Wang wrote:
> When using V3D rendering with CONFIG_DMA_API_DEBUG enabled, the
> kernel occasionally reports a segment size mismatch. This is because
> 'max_seg_size' is not set. The kernel defaults to 64K. setting
> 'max_seg_size' to the maximum will prevent 'debug_dma_map_sg()'
> from complaining about the over-mapping of the V3D segment length.
>
> DMA-API: v3d 1002000000.v3d: mapping sg segment longer than device
> claims to support [len=8290304] [max=65536]
> WARNING: CPU: 0 PID: 493 at kernel/dma/debug.c:1179
> debug_dma_map_sg+0x330/0x388
> CPU: 0 UID: 0 PID: 493 Comm: Xorg Not tainted 6.12.53-yocto-standard #1
> Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
> pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : debug_dma_map_sg+0x330/0x388
> lr : debug_dma_map_sg+0x330/0x388
> sp : ffff8000829a3ac0
> x29: ffff8000829a3ac0 x28: 0000000000000001 x27: ffff8000813fe000
> x26: ffffc1ffc0000000 x25: ffff00010fdeb760 x24: 0000000000000000
> x23: ffff8000816a9bf0 x22: 0000000000000001 x21: 0000000000000002
> x20: 0000000000000002 x19: ffff00010185e810 x18: ffffffffffffffff
> x17: 69766564206e6168 x16: 74207265676e6f6c x15: 20746e656d676573
> x14: 20677320676e6970 x13: 5d34303334393134 x12: 0000000000000000
> x11: 00000000000000c0 x10: 00000000000009c0 x9 : ffff8000800e0b7c
> x8 : ffff00010a315ca0 x7 : ffff8000816a5110 x6 : 0000000000000001
> x5 : 000000000000002b x4 : 0000000000000002 x3 : 0000000000000008
> x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff00010a315280
> Call trace:
> debug_dma_map_sg+0x330/0x388
> __dma_map_sg_attrs+0xc0/0x278
> dma_map_sgtable+0x30/0x58
> drm_gem_shmem_get_pages_sgt+0xb4/0x140
> v3d_bo_create_finish+0x28/0x130 [v3d]
> v3d_create_bo_ioctl+0x54/0x180 [v3d]
> drm_ioctl_kernel+0xc8/0x140
> drm_ioctl+0x2d4/0x4d8
>
> [...]
Applied, thanks!
[1/1] drm/v3d: Set DMA segment size to avoid debug warnings
commit: 9eb018828b1b30dfba689c060735c50fc5b9f704
Best regards,
- Maíra
