On Mon, Feb 22, 2021 at 01:43:26PM +0100, Thomas Zimmermann wrote:
> USB devices cannot perform DMA and hence have no dma_mask set in their
> device structure. Importing dmabuf into a USB-based driver fails, which
> break joining and mirroring of display in X11. A corresponding error
> message is shown below.
>
> [ 60.050199] ------------[ cut here ]------------
> [ 60.055092] WARNING: CPU: 0 PID: 1403 at kernel/dma/mapping.c:190 dma_map_sg_attrs+0x8f/0xc0
> [ 60.064331] Modules linked in: af_packet(E) rfkill(E) dmi_sysfs(E) intel_rapl_msr(E) intel_rapl_common(E) snd_hda_codec_realtek(E) snd_hda_codec_generic(E) ledtrig_audio(E) snd_hda_codec_hdmi(E) x86_pkg_temp_thermal(E) intel_powerclam)
> [ 60.064801] wmi(E) video(E) btrfs(E) blake2b_generic(E) libcrc32c(E) crc32c_intel(E) xor(E) raid6_pq(E) sg(E) dm_multipath(E) dm_mod(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) msr(E) efivarfs(E)
> [ 60.170778] CPU: 0 PID: 1403 Comm: Xorg.bin Tainted: G E 5.11.0-rc5-1-default+ #747
> [ 60.179841] Hardware name: Dell Inc. OptiPlex 9020/0N4YC8, BIOS A24 10/24/2018
> [ 60.187145] RIP: 0010:dma_map_sg_attrs+0x8f/0xc0
> [ 60.191822] Code: 4d 85 ff 75 2b 49 89 d8 44 89 e1 44 89 f2 4c 89 ee 48 89 ef e8 62 30 00 00 85 c0 78 36 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 0b <0f> 0b 31 c0 eb ed 49 8d 7f 50 e8 72 f5 2a 00 49 8b 47 50 49 89 d8
> [ 60.210770] RSP: 0018:ffffc90001d6fc18 EFLAGS: 00010246
> [ 60.216062] RAX: 0000000000000000 RBX: 0000000000000020 RCX: ffffffffb31e677b
> [ 60.223274] RDX: dffffc0000000000 RSI: ffff888212c10600 RDI: ffff8881b08a9488
> [ 60.230501] RBP: ffff8881b08a9030 R08: 0000000000000020 R09: ffff888212c10600
> [ 60.237710] R10: ffffed10425820df R11: 0000000000000001 R12: 0000000000000000
> [ 60.244939] R13: ffff888212c10600 R14: 0000000000000008 R15: 0000000000000000
> [ 60.252155] FS: 00007f08ac2b2f00(0000) GS:ffff8887cbe00000(0000) knlGS:0000000000000000
> [ 60.260333] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 60.266150] CR2: 000055831c899be8 CR3: 000000015372e006 CR4: 00000000001706f0
> [ 60.273369] Call Trace:
> [ 60.275845] drm_gem_map_dma_buf+0xb4/0x120
> [ 60.280089] dma_buf_map_attachment+0x15d/0x1e0
> [ 60.284688] drm_gem_prime_import_dev.part.0+0x5d/0x140
> [ 60.289984] drm_gem_prime_fd_to_handle+0x213/0x280
> [ 60.294931] ? drm_prime_destroy_file_private+0x30/0x30
> [ 60.300224] drm_ioctl_kernel+0x131/0x180
> [ 60.304291] ? drm_setversion+0x230/0x230
> [ 60.308366] ? drm_prime_destroy_file_private+0x30/0x30
> [ 60.313659] drm_ioctl+0x2f1/0x500
> [ 60.317118] ? drm_version+0x150/0x150
> [ 60.320903] ? lock_downgrade+0xa0/0xa0
> [ 60.324806] ? do_vfs_ioctl+0x5f4/0x680
> [ 60.328694] ? __fget_files+0x13e/0x210
> [ 60.332591] ? ioctl_fiemap.isra.0+0x1a0/0x1a0
> [ 60.337102] ? __fget_files+0x15d/0x210
> [ 60.340990] __x64_sys_ioctl+0xb9/0xf0
> [ 60.344795] do_syscall_64+0x33/0x80
> [ 60.348427] entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [ 60.353542] RIP: 0033:0x7f08ac7b53cb
> [ 60.357168] Code: 89 d8 49 8d 3c 1c 48 f7 d8 49 39 c4 72 b5 e8 1c ff ff ff 85 c0 78 ba 4c 89 e0 5b 5d 41 5c c3 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 75 ba 0c 00 f7 d8 64 89 01 48
> [ 60.376108] RSP: 002b:00007ffeabc89fc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> [ 60.383758] RAX: ffffffffffffffda RBX: 00007ffeabc8a00c RCX: 00007f08ac7b53cb
> [ 60.390970] RDX: 00007ffeabc8a00c RSI: 00000000c00c642e RDI: 000000000000000d
> [ 60.398221] RBP: 00000000c00c642e R08: 000055831c691d00 R09: 000055831b2ec010
> [ 60.405446] R10: 00007f08acf6ada0 R11: 0000000000000246 R12: 000055831c691d00
> [ 60.412667] R13: 000000000000000d R14: 00000000007e9000 R15: 0000000000000000
> [ 60.419903] irq event stamp: 672893
> [ 60.423441] hardirqs last enabled at (672913): [<ffffffffb31b796d>] console_unlock+0x44d/0x500
> [ 60.432230] hardirqs last disabled at (672922): [<ffffffffb31b7963>] console_unlock+0x443/0x500
> [ 60.441021] softirqs last enabled at (672940): [<ffffffffb46003dd>] __do_softirq+0x3dd/0x554
> [ 60.449634] softirqs last disabled at (672931): [<ffffffffb44010f2>] asm_call_irq_on_stack+0x12/0x20
> [ 60.458871] ---[ end trace f2f88696eb17806c ]---
>
> This patch introduces struct drm_driver.gem_prime_create_object, which
> creates a GEM object during the import. Drivers should implement this
> callback and handle DMA S/G table support by themselves. For USB-based
> drivers, the patch adds an implementation without DMA-related code.
>
> The original interface struct drm_driver.gem_prime_import_sg_table
> is deprecated. All drivers should switch over.
>
> Tested by joining/mirroring displays of udl and radeon un der Gnome/X11.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Fixes: 6eb0233ec2d0 ("usb: don't inherity DMA properties for USB devices")
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Cc: Johan Hovold <johan@xxxxxxxxxx>
> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> Cc: "Ahmed S. Darwish" <a.darwish@xxxxxxxxxxxxx>
> Cc: Oliver Neukum <oneukum@xxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Felipe Balbi <balbi@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v5.10+
> ---
> drivers/gpu/drm/drm_prime.c | 43 +++++++++++++++++++++------------
> drivers/gpu/drm/tiny/gm12u320.c | 7 ++++++
> drivers/gpu/drm/udl/udl_drv.c | 7 ++++++
> include/drm/drm_drv.h | 12 +++++++++
> 4 files changed, 54 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 2a54f86856af..9bb30e843a44 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -923,7 +923,8 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
> }
> }
>
> - if (!dev->driver->gem_prime_import_sg_table)
> + if (!dev->driver->gem_prime_import_sg_table &&
> + !dev->driver->gem_prime_create_object)
> return ERR_PTR(-EINVAL);
>
> attach = dma_buf_attach(dma_buf, attach_dev);
> @@ -932,25 +933,37 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
>
> get_dma_buf(dma_buf);
>
> - sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
> - if (IS_ERR(sgt)) {
> - ret = PTR_ERR(sgt);
> - goto fail_detach;
> - }
> + if (dev->driver->gem_prime_create_object) {
> + obj = dev->driver->gem_prime_create_object(dev, attach);
> + if (IS_ERR(obj)) {
> + ret = PTR_ERR(obj);
> + goto fail_detach;
> + }
>
> - obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
> - if (IS_ERR(obj)) {
> - ret = PTR_ERR(obj);
> - goto fail_unmap;
> - }
> + if (!obj->import_attach)
> + obj->import_attach = attach;
If you don't set import_attach then the refcounting and double-import
prevention goes all kinds of wrong. So unfortunately it's not that easy.
-Daniel
> + if (!obj->resv)
> + obj->resv = dma_buf->resv;
> + } else {
> + sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
> + if (IS_ERR(sgt)) {
> + ret = PTR_ERR(sgt);
> + goto fail_detach;
> + }
>
> - obj->import_attach = attach;
> - obj->resv = dma_buf->resv;
> + obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
> + if (IS_ERR(obj)) {
> + ret = PTR_ERR(obj);
> + dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
> + goto fail_detach;
> + }
> +
> + obj->import_attach = attach;
> + obj->resv = dma_buf->resv;
> + }
>
> return obj;
>
> -fail_unmap:
> - dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
> fail_detach:
> dma_buf_detach(dma_buf, attach);
> dma_buf_put(dma_buf);
> diff --git a/drivers/gpu/drm/tiny/gm12u320.c b/drivers/gpu/drm/tiny/gm12u320.c
> index 0b4f4f2af1ef..9f13a7c7c2da 100644
> --- a/drivers/gpu/drm/tiny/gm12u320.c
> +++ b/drivers/gpu/drm/tiny/gm12u320.c
> @@ -601,6 +601,12 @@ static const uint64_t gm12u320_pipe_modifiers[] = {
>
> DEFINE_DRM_GEM_FOPS(gm12u320_fops);
>
> +static struct drm_gem_object *gm12u320_gem_prime_create_object(struct drm_device *dev,
> + struct dma_buf_attachment *attach)
> +{
> + return drm_gem_shmem_prime_import_sg_table(dev, attach, NULL);
> +}
> +
> static const struct drm_driver gm12u320_drm_driver = {
> .driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
>
> @@ -612,6 +618,7 @@ static const struct drm_driver gm12u320_drm_driver = {
>
> .fops = &gm12u320_fops,
> DRM_GEM_SHMEM_DRIVER_OPS,
> + .gem_prime_create_object = gm12u320_gem_prime_create_object,
> };
>
> static const struct drm_mode_config_funcs gm12u320_mode_config_funcs = {
> diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
> index 9269092697d8..fdf37b44a956 100644
> --- a/drivers/gpu/drm/udl/udl_drv.c
> +++ b/drivers/gpu/drm/udl/udl_drv.c
> @@ -34,12 +34,19 @@ static int udl_usb_resume(struct usb_interface *interface)
>
> DEFINE_DRM_GEM_FOPS(udl_driver_fops);
>
> +static struct drm_gem_object *udl_gem_prime_create_object(struct drm_device *dev,
> + struct dma_buf_attachment *attach)
> +{
> + return drm_gem_shmem_prime_import_sg_table(dev, attach, NULL);
> +}
> +
> static const struct drm_driver driver = {
> .driver_features = DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
>
> /* GEM hooks */
> .fops = &udl_driver_fops,
> DRM_GEM_SHMEM_DRIVER_OPS,
> + .gem_prime_create_object = udl_gem_prime_create_object,
>
> .name = DRIVER_NAME,
> .desc = DRIVER_DESC,
> diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
> index 827838e0a97e..77657d649ca6 100644
> --- a/include/drm/drm_drv.h
> +++ b/include/drm/drm_drv.h
> @@ -369,11 +369,23 @@ struct drm_driver {
> */
> struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
> struct dma_buf *dma_buf);
> + /**
> + * @gem_prime_create_object:
> + *
> + * Optional hook used by the PRIME helper functions
> + * drm_gem_prime_import() respectively drm_gem_prime_import_dev().
> + */
> + struct drm_gem_object *(*gem_prime_create_object)(
> + struct drm_device *dev,
> + struct dma_buf_attachment *attach);
> /**
> * @gem_prime_import_sg_table:
> *
> * Optional hook used by the PRIME helper functions
> * drm_gem_prime_import() respectively drm_gem_prime_import_dev().
> + *
> + * TODO: This function is deprecated in favor of @drm_driver.gem_prime_create_object.
> + * Drivers should switch over and implement SG-table support by themselves.
> */
> struct drm_gem_object *(*gem_prime_import_sg_table)(
> struct drm_device *dev,
> --
> 2.30.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
