<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Mon, Jul 10, 2017 at 8:45 AM, Christian König <span dir="ltr"><<a href="mailto:deathsimple@vodafone.de" target="_blank">deathsimple@vodafone.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF"><div><div class="gmail-h5">
<div class="gmail-m_-226855681158848481moz-cite-prefix">Am 10.07.2017 um 17:28 schrieb Jason
Ekstrand:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">On Wed, Jul 5, 2017 at 6:04 PM, Dave
Airlie <span dir="ltr"><<a href="mailto:airlied@gmail.com" target="_blank">airlied@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">From:
Dave Airlie <<a href="mailto:airlied@redhat.com" target="_blank">airlied@redhat.com</a>><br>
<br>
This interface will allow sync object to be used to back<br>
Vulkan fences. This API is pretty much the vulkan fence
waiting<br>
API, and I've ported the code from amdgpu.<br>
<br>
v2: accept relative timeout, pass remaining time back<br>
to userspace.<br>
v3: return to absolute timeouts.<br>
v4: absolute zero = poll,<br>
rewrite any/all code to have same operation for arrays<br>
return -EINVAL for 0 fences.<br>
v4.1: fixup fences allocation check, use u64_to_user_ptr<br>
v5: move to sec/nsec, and use timespec64 for calcs.<br>
v6: use -ETIME and drop the out status flag. (-ETIME<br>
is suggested by ickle, I can feel a shed painting)<br>
<br>
Signed-off-by: Dave Airlie <<a href="mailto:airlied@redhat.com" target="_blank">airlied@redhat.com</a>><br>
---<br>
drivers/gpu/drm/drm_internal.<wbr>h | 2 +<br>
drivers/gpu/drm/drm_ioctl.c | 2 +<br>
drivers/gpu/drm/drm_syncobj.<wbr>c | 142
++++++++++++++++++++++++++++++<wbr>+++++++++++<br>
include/uapi/drm/drm.h | 13 ++++<br>
4 files changed, 159 insertions(+)<br>
<br>
diff --git a/drivers/gpu/drm/drm_internal<wbr>.h
b/drivers/gpu/drm/drm_internal<wbr>.h<br>
index 5cecc97..d71b50d 100644<br>
--- a/drivers/gpu/drm/drm_internal<wbr>.h<br>
+++ b/drivers/gpu/drm/drm_internal<wbr>.h<br>
@@ -157,3 +157,5 @@ int drm_syncobj_handle_to_fd_ioctl<wbr>(struct
drm_device *dev, void *data,<br>
struct drm_file
*file_private);<br>
int drm_syncobj_fd_to_handle_ioctl<wbr>(struct drm_device
*dev, void *data,<br>
struct drm_file
*file_private);<br>
+int drm_syncobj_wait_ioctl(struct drm_device *dev, void
*data,<br>
+ struct drm_file *file_private);<br>
diff --git a/drivers/gpu/drm/drm_ioctl.c
b/drivers/gpu/drm/drm_ioctl.c<br>
index f1e5681..385ce74 100644<br>
--- a/drivers/gpu/drm/drm_ioctl.c<br>
+++ b/drivers/gpu/drm/drm_ioctl.c<br>
@@ -657,6 +657,8 @@ static const struct drm_ioctl_desc
drm_ioctls[] = {<br>
DRM_UNLOCKED|DRM_RENDER_ALLOW)<wbr>,<br>
DRM_IOCTL_DEF(DRM_IOCTL_SYNCOB<wbr>J_FD_TO_HANDLE,
drm_syncobj_fd_to_handle_ioctl<wbr>,<br>
DRM_UNLOCKED|DRM_RENDER_ALLOW)<wbr>,<br>
+ DRM_IOCTL_DEF(DRM_IOCTL_SYNCO<wbr>BJ_WAIT,
drm_syncobj_wait_ioctl,<br>
+ DRM_UNLOCKED|DRM_RENDER_<wbr>ALLOW),<br>
};<br>
<br>
#define DRM_CORE_IOCTL_COUNT ARRAY_SIZE( drm_ioctls )<br>
diff --git a/drivers/gpu/drm/drm_syncobj.<wbr>c
b/drivers/gpu/drm/drm_syncobj.<wbr>c<br>
index 89441bc..2d5a7a1 100644<br>
--- a/drivers/gpu/drm/drm_syncobj.<wbr>c<br>
+++ b/drivers/gpu/drm/drm_syncobj.<wbr>c<br>
@@ -1,5 +1,7 @@<br>
/*<br>
* Copyright 2017 Red Hat<br>
+ * Parts ported from amdgpu (fence wait code).<br>
+ * Copyright 2016 Advanced Micro Devices, Inc.<br>
*<br>
* Permission is hereby granted, free of charge, to any
person obtaining a<br>
* copy of this software and associated documentation
files (the "Software"),<br>
@@ -31,6 +33,9 @@<br>
* that contain an optional fence. The fence can be
updated with a new<br>
* fence, or be NULL.<br>
*<br>
+ * syncobj's can be waited upon, where it will wait for
the underlying<br>
+ * fence.<br>
+ *<br>
* syncobj's can be export to fd's and back, these fd's
are opaque and<br>
* have no other use case, except passing the syncobj
between processes.<br>
*<br>
@@ -451,3 +456,140 @@ drm_syncobj_fd_to_handle_ioctl<wbr>(struct
drm_device *dev, void *data,<br>
return drm_syncobj_fd_to_handle(file_<wbr>private,
args->fd,<br>
&args->handle);<br>
}<br>
+<br>
+/**<br>
+ * drm_timeout_abs_to_jiffies - calculate jiffies timeout
from absolute value<br>
+ *<br>
+ * @timeout_sec: timeout sec component, 0 for poll<br>
+ * @timeout_nsec: timeout nsec component in ns, 0 for
poll<br>
+ * both must be 0 for poll.<br>
+ *<br>
+ * Calculate the timeout in jiffies from an absolute time
in sec/nsec.<br>
+ */<br>
+static unsigned long drm_timeout_abs_to_jiffies(int<wbr>64_t
timeout_sec, uint64_t timeout_nsec)<br>
+{<br>
+ struct timespec64 abs_timeout, timeout,
max_jiffy_timespec;<br>
+ unsigned long timeout_jiffies;<br>
+<br>
+ /* make 0 timeout means poll - absolute 0 doesn't
seem valid */<br>
+ if (timeout_sec == 0 && timeout_nsec == 0)<br>
+ return 0;<br>
+<br>
+ abs_timeout.tv_sec = timeout_sec;<br>
+ abs_timeout.tv_nsec = timeout_nsec;<br>
+<br>
+ /* clamp timeout if it's to large */<br>
+ if (!timespec64_valid_strict(&abs<wbr>_timeout))<br>
+ return MAX_SCHEDULE_TIMEOUT - 1;<br>
+<br>
+ timeout = timespec64_sub(abs_timeout,
ktime_to_timespec64(ktime_get(<wbr>)));<br>
+ if (!timespec64_valid(&timeout))<br>
+ return 0;<br>
+<br>
+ jiffies_to_timespec64(MAX_JIF<wbr>FY_OFFSET,
&max_jiffy_timespec);<br>
+ if (timespec64_compare(&timeout,
&max_jiffy_timespec) >= 0)<br>
+ return MAX_SCHEDULE_TIMEOUT - 1;<br>
+<br>
+ timeout_jiffies = timespec64_to_jiffies(&timeout<wbr>);<br>
+ /* clamp timeout to avoid infinite timeout */<br>
+ if (timeout_jiffies >= MAX_SCHEDULE_TIMEOUT)<br>
+ return MAX_SCHEDULE_TIMEOUT - 1;<br>
+<br>
+ return timeout_jiffies + 1;<br>
+}<br>
+<br>
+static int drm_syncobj_wait_fences(struct drm_device
*dev,<br>
+ struct drm_file
*file_private,<br>
+ struct drm_syncobj_wait
*wait,<br>
+ struct dma_fence
**fences)<br>
+{<br>
+ unsigned long timeout =
drm_timeout_abs_to_jiffies(wai<wbr>t->timeout_sec,
wait->timeout_nsec);<br>
+ int ret = 0;<br>
+ uint32_t first = ~0;<br>
+<br>
+ if (wait->flags &
DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AL<wbr>L) {<br>
+ int i;<br>
+ for (i = 0; i < wait->count_handles;
i++) {<br>
+ ret =
dma_fence_wait_timeout(fences[<wbr>i], true, timeout);<br>
+<br>
+ if (ret < 0)<br>
+ return ret;<br>
+ if (ret == 0)<br>
+ break;<br>
+ timeout = ret;<br>
+ }<br>
+ first = 0;<br>
+ } else {<br>
+ ret = dma_fence_wait_any_timeout(fen<wbr>ces,<br>
+
wait->count_handles,<br>
+ true,
timeout,<br>
+
&first);<br>
+ }<br>
+<br>
+ if (ret < 0)<br>
+ return ret;<br>
+<br>
+ wait->first_signaled = first;<br>
+ if (ret == 0)<br>
+ return -ETIME;<br>
+ return 0;<br>
+}<br>
+<br>
+int<br>
+drm_syncobj_wait_ioctl(struct drm_device *dev, void
*data,<br>
+ struct drm_file *file_private)<br>
+{<br>
+ struct drm_syncobj_wait *args = data;<br>
+ uint32_t *handles;<br>
+ struct dma_fence **fences;<br>
+ int ret = 0;<br>
+ int i;<br>
+<br>
+ if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ))<br>
+ return -ENODEV;<br>
+<br>
+ if (args->flags != 0 && args->flags
!= DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AL<wbr>L)<br>
+ return -EINVAL;<br>
+<br>
+ if (args->count_handles == 0)<br>
+ return -EINVAL;<br>
+<br>
+ /* Get the handles from userspace */<br>
+ handles = kmalloc_array(args->count_hand<wbr>les,
sizeof(uint32_t),<br>
+ GFP_KERNEL);<br>
+ if (handles == NULL)<br>
+ return -ENOMEM;<br>
+<br>
+ if (copy_from_user(handles,<br>
+
u64_to_user_ptr(args->handles)<wbr>,<br>
+ sizeof(uint32_t) *
args->count_handles)) {<br>
+ ret = -EFAULT;<br>
+ goto err_free_handles;<br>
+ }<br>
+<br>
+ fences = kcalloc(args->count_handles,<br>
+ sizeof(struct dma_fence *),
GFP_KERNEL);<br>
+ if (!fences) {<br>
+ ret = -ENOMEM;<br>
+ goto err_free_handles;<br>
+ }<br>
+<br>
+ for (i = 0; i < args->count_handles; i++) {<br>
+ ret = drm_syncobj_fence_get(file_pri<wbr>vate,
handles[i],<br>
+
&fences[i]);<br>
+ if (ret)<br>
+ goto err_free_fence_array;<br>
+ }<br>
+<br>
+ ret = drm_syncobj_wait_fences(dev, file_private,<br>
+ args, fences);<br>
</blockquote>
<div><br>
</div>
<div>So, reading some CTS tests again, and I think we have a
problem here. The Vulkan spec allows you to wait on a
fence that is in the unsignaled state.</div>
</div>
</div>
</div>
</blockquote>
<br></div></div>
At least on the closed source driver that would be illegal as far as
I know.<br></div></blockquote><div><br></div><div>Then they are doing workarounds in userspace. There are definitely CTS tests for this:<br><br><a href="https://github.com/KhronosGroup/VK-GL-CTS/blob/master/external/vulkancts/modules/vulkan/synchronization/vktSynchronizationBasicFenceTests.cpp#L74">https://github.com/KhronosGroup/VK-GL-CTS/blob/master/external/vulkancts/modules/vulkan/synchronization/vktSynchronizationBasicFenceTests.cpp#L74</a><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
You can't wait on a semaphore before the signal operation is send
down to the kerel.</div></blockquote><div><br></div><div>We (Intel) deal with this today by tracking whether or not the fence has been submitted and using a condition variable in userspace to sort it all out. If we ever want to share fences across processes (which we do), then this needs to be sorted in the kernel. <br><br></div><div>--Jason<br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div bgcolor="#FFFFFF">
Regards,<br>
Christian.<div><div class="gmail-h5"><br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> In theory, you could have thread A start waiting on a
fence before thread B submits the work which triggers that
fence. This means that the dma_fence may not exist yet
when vkWaitForFences gets called. If we really want to
support the full Vulkan usage, we need to somehow support
missing dma_fences by waiting for the dma_fence to show
up. Unfortunately, I don't know enough about the internal
kernel APIs to know what that would look like.<br>
</div>
</div>
</div>
</div>
</blockquote>
</div></div><blockquote type="cite"><div><div class="gmail-h5">
<div dir="ltr">
<div class="gmail_extra">
<div class="gmail_quote">
<div> </div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
+<br>
+err_free_fence_array:<br>
+ for (i = 0; i < args->count_handles; i++)<br>
+ dma_fence_put(fences[i]);<br>
+ kfree(fences);<br>
+err_free_handles:<br>
+ kfree(handles);<br>
+<br>
+ return ret;<br>
+}<br>
diff --git a/include/uapi/drm/drm.h
b/include/uapi/drm/drm.h<br>
index 101593a..91746a7 100644<br>
--- a/include/uapi/drm/drm.h<br>
+++ b/include/uapi/drm/drm.h<br>
@@ -718,6 +718,18 @@ struct drm_syncobj_handle {<br>
__u32 pad;<br>
};<br>
<br>
+#define DRM_SYNCOBJ_WAIT_FLAGS_WAIT_AL<wbr>L (1 <<
0)<br>
+struct drm_syncobj_wait {<br>
+ __u64 handles;<br>
+ /* absolute timeout */<br>
+ __s64 timeout_sec;<br>
+ __s64 timeout_nsec;<br>
+ __u32 count_handles;<br>
+ __u32 flags;<br>
+ __u32 first_signaled; /* only valid when not
waiting all */<br>
+ __u32 pad;<br>
+};<br>
+<br>
#if defined(__cplusplus)<br>
}<br>
#endif<br>
@@ -840,6 +852,7 @@ extern "C" {<br>
#define DRM_IOCTL_SYNCOBJ_DESTROY DRM_IOWR(0xC0,
struct drm_syncobj_destroy)<br>
#define DRM_IOCTL_SYNCOBJ_HANDLE_TO_FD DRM_IOWR(0xC1,
struct drm_syncobj_handle)<br>
#define DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE DRM_IOWR(0xC2,
struct drm_syncobj_handle)<br>
+#define DRM_IOCTL_SYNCOBJ_WAIT DRM_IOWR(0xC3,
struct drm_syncobj_wait)<br>
<br>
/**<br>
* Device specific ioctls should only be in their
respective headers<br>
<span class="gmail-m_-226855681158848481HOEnZb"><font color="#888888">--<br>
2.9.4<br>
<br>
______________________________<wbr>_________________<br>
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</font></span></blockquote>
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</blockquote></div><br></div></div>