Am 20.02.21 um 14:02 schrieb Noralf Trønnes:
Den 19.02.2021 14.40, skrev Thomas Zimmermann:
Fixes a regression for udl and probably other USB-based drivers where
joining and mirroring displays fails.
Joining displays requires importing a dma_buf from another DRM driver.
These devices don't support DMA and therefore have no DMA mask. Trying
to map imported buffers from a DMA-able memory zone fails with an error.
An example 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
I'm working on a USB display driver and got the same splat (although
from i915_gem_map_dma_buf) and silenced it using:
ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(64));
But I understand now that this is not the solution.
Since the USB host controller can do DMA, would the following be an
acceptable solution?
I'm not an expert for the USB stuff. But from a 10 mile high view I
would say that this is the right approach, yes.
Regards,
Christian.
static struct drm_gem_object *gud_gem_prime_import(struct drm_device
*drm, struct dma_buf *dma_buf)
{
struct usb_device *usb = gud_to_usb_device(to_gud_device(drm));
drm_dbg_prime(drm, "usb->bus->controller=%s\n",
dev_name(usb->bus->controller));
return drm_gem_prime_import_dev(drm, dma_buf, usb->bus->controller);
}
static const struct drm_driver gud_drm_driver = {
.gem_prime_import = gud_gem_prime_import,
};
Noralf.
[ 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 ]---
For the fix, we don't call dma_map_sgtable() for devices without the
DMA mask. Drivers for such devices have to map the imported buffer into
kernel address space and perfom the copy operation in software.
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: "Ahmed S. Darwish" <a.darwish@xxxxxxxxxxxxx>
Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Cc: Oliver Neukum <oneukum@xxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v5.10+
---
drivers/gpu/drm/drm_prime.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 2a54f86856af..d5a39fe76b78 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -603,10 +603,15 @@ EXPORT_SYMBOL(drm_gem_map_detach);
* @attach: attachment whose scatterlist is to be returned
* @dir: direction of DMA transfer
*
- * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
- * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
+ * Calls &drm_gem_object_funcs.get_sg_table and, if possible, maps the scatterlist.
+ * This can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
* with drm_gem_unmap_dma_buf().
*
+ * Devices on some peripheral busses, such as USB, cannot use DMA. In this case,
+ * pages in the scatterlist remain unmapped. Drivers for such devices should acquire
+ * a mapping with dma_buf_vmap() and implement copy operation via bus-specific
+ * interfaces.
+ *
* Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
* on error. May return -EINTR if it is interrupted by a signal.
*/
@@ -627,12 +632,14 @@ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
if (IS_ERR(sgt))
return sgt;
- ret = dma_map_sgtable(attach->dev, sgt, dir,
- DMA_ATTR_SKIP_CPU_SYNC);
- if (ret) {
- sg_free_table(sgt);
- kfree(sgt);
- sgt = ERR_PTR(ret);
+ if (attach->dev->dma_mask) {
+ ret = dma_map_sgtable(attach->dev, sgt, dir,
+ DMA_ATTR_SKIP_CPU_SYNC);
+ if (ret) {
+ sg_free_table(sgt);
+ kfree(sgt);
+ sgt = ERR_PTR(ret);
+ }
}
return sgt;
@@ -654,7 +661,9 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
if (!sgt)
return;
- dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
+ if (attach->dev->dma_mask)
+ dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
+
sg_free_table(sgt);
kfree(sgt);
}
--
2.30.0
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