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@suse.de Fixes: 6eb0233ec2d0 ("usb: don't inherity DMA properties for USB devices") Cc: Christoph Hellwig hch@lst.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Alan Stern stern@rowland.harvard.edu Cc: Johan Hovold johan@kernel.org Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Mathias Nyman mathias.nyman@linux.intel.com Cc: "Ahmed S. Darwish" a.darwish@linutronix.de Cc: Oliver Neukum oneukum@suse.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Felipe Balbi balbi@kernel.org Cc: stable@vger.kernel.org # 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