On Fri, Apr 16, 2021 at 12:25 AM Ian Romanick <idr@xxxxxxxxxxxxxxx> wrote:
> On 4/15/21 8:59 AM, Matthew Auld wrote:
> > Add a note about the two-step process.
> >
> > Suggested-by: Daniel Vetter <daniel@xxxxxxxx>
> > Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> > Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> > Cc: Jordan Justen <jordan.l.justen@xxxxxxxxx>
> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> > Cc: Kenneth Graunke <kenneth@xxxxxxxxxxxxx>
> > Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> > Cc: Dave Airlie <airlied@xxxxxxxxx>
> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > Cc: mesa-dev@xxxxxxxxxxxxxxxxxxxxx
> > ---
> > include/uapi/drm/i915_drm.h | 57 ++++++++++++++++++++++++++++++-------
> > 1 file changed, 46 insertions(+), 11 deletions(-)
> >
> > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> > index d9c954a5a456..ef36f1a0adde 100644
> > --- a/include/uapi/drm/i915_drm.h
> > +++ b/include/uapi/drm/i915_drm.h
> > @@ -2210,14 +2210,23 @@ struct drm_i915_perf_oa_config {
> > __u64 flex_regs_ptr;
> > };
> >
> > +/**
> > + * struct drm_i915_query_item - An individual query for the kernel to process.
> > + *
> > + * The behaviour is determined by the @query_id. Note that exactly what
>
> Since we just had a big discussion about this on mesa-dev w.r.t. Mesa
> code and documentation... does the kernel have a policy about which
> flavor (pun intended) of English should be used?
I'm not finding it documented in
https://dri.freedesktop.org/docs/drm/doc-guide/sphinx.html but I
thought we've discussed it. Adding linux-doc and Jon Corbet.
-Daniel
>
> > + * @data_ptr is also depends on the specific @query_id.
> > + */
> > struct drm_i915_query_item {
> > + /** @query_id: The id for this query */
> > __u64 query_id;
> > #define DRM_I915_QUERY_TOPOLOGY_INFO 1
> > #define DRM_I915_QUERY_ENGINE_INFO 2
> > #define DRM_I915_QUERY_PERF_CONFIG 3
> > /* Must be kept compact -- no holes and well documented */
> >
> > - /*
> > + /**
> > + * @length:
> > + *
> > * When set to zero by userspace, this is filled with the size of the
> > * data to be written at the data_ptr pointer. The kernel sets this
> > * value to a negative value to signal an error on a particular query
> > @@ -2225,21 +2234,26 @@ struct drm_i915_query_item {
> > */
> > __s32 length;
> >
> > - /*
> > + /**
> > + * @flags:
> > + *
> > * When query_id == DRM_I915_QUERY_TOPOLOGY_INFO, must be 0.
> > *
> > * When query_id == DRM_I915_QUERY_PERF_CONFIG, must be one of the
> > - * following :
> > - * - DRM_I915_QUERY_PERF_CONFIG_LIST
> > - * - DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID
> > - * - DRM_I915_QUERY_PERF_CONFIG_FOR_UUID
> > + * following:
> > + *
> > + * - DRM_I915_QUERY_PERF_CONFIG_LIST
> > + * - DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID
> > + * - DRM_I915_QUERY_PERF_CONFIG_FOR_UUID
> > */
> > __u32 flags;
> > #define DRM_I915_QUERY_PERF_CONFIG_LIST 1
> > #define DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID 2
> > #define DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_ID 3
> >
> > - /*
> > + /**
> > + * @data_ptr:
> > + *
> > * Data will be written at the location pointed by data_ptr when the
> > * value of length matches the length of the data to be written by the
> > * kernel.
> > @@ -2247,16 +2261,37 @@ struct drm_i915_query_item {
> > __u64 data_ptr;
> > };
> >
> > +/**
> > + * struct drm_i915_query - Supply an array of drm_i915_query_item for the kernel
> > + * to fill out.
> > + *
> > + * Note that this is generally a two step process for each drm_i915_query_item
> > + * in the array:
> > + *
> > + * 1.) Call the DRM_IOCTL_I915_QUERY, giving it our array of
> > + * drm_i915_query_item, with drm_i915_query_item.size set to zero. The
> > + * kernel will then fill in the size, in bytes, which tells userspace how
> > + * memory it needs to allocate for the blob(say for an array of
> > + * properties).
> > + *
> > + * 2.) Next we call DRM_IOCTL_I915_QUERY again, this time with the
> > + * drm_i915_query_item.data_ptr equal to our newly allocated blob. Note
> > + * that the i915_query_item.size should still be the same as what the
> > + * kernel previously set. At this point the kernel can fill in the blob.
> > + *
> > + */
> > struct drm_i915_query {
> > + /** @num_items: The number of elements in the @items_ptr array */
> > __u32 num_items;
> >
> > - /*
> > - * Unused for now. Must be cleared to zero.
> > + /**
> > + * @flags: Unused for now. Must be cleared to zero.
> > */
> > __u32 flags;
> >
> > - /*
> > - * This points to an array of num_items drm_i915_query_item structures.
> > + /**
> > + * @items_ptr: This points to an array of num_items drm_i915_query_item
> > + * structures.
> > */
> > __u64 items_ptr;
> > };
> >
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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