[PATCH] Add drm ioctl DRM_IOCTL_MODE_GETFB2 & associated helpers.
Joe Kniss
djmk at google.com
Tue Aug 1 17:24:25 UTC 2017
Thanks for the quick review!
On Tue, Aug 1, 2017 at 5:09 AM, Laurent Pinchart <laurent.pinchart@
ideasonboard.com> wrote:
> Hi Joe,
>
> Thank you for the patch.
>
> On Monday 31 Jul 2017 11:29:13 Joe Kniss wrote:
> > New getfb2 functionality uses drm_mode_fb_cmd2 struct to be symmetric
> > with addfb2.
>
> What's the use case for this ? We haven't needed such an ioctl for so long
> that it seemed to me that userspace doesn't really need it, but I could be
> wrong.
>
> Sorry, I failed to reference the original email. Here it is:
<snip>
I am a recent addition to Google's ChromeOS gfx team. I am currently
working on display testing and reporting. An important part of this is
our screen capture tool, which works by querying drm for crtcs, planes, and
fbs. Unfortunately, there is only limited information available via
drmModeGetFB(), which often wrong information when drmModeAddFB2() was used
to create the fbs. For example, if the pixel format is NV12 or YUV420,
the fb returned knows nothing about the additional buffer planes required
by these formats. Ideally, we would like a function (e.g. drmModeGetFB2)
to return information symmetric with drmModeAddFB2 including the pixel
format id, buffer plane information etc.
</snip>
ChromeOS has needed this functionality from the start, for both testing and
error reporting. We got away with guessing the buffer's format (32bit
xrgb) until now. We are now enabling overlays and more formats including
multi-planar (e.g. NV12). Current getfb() reports neither the pixel format
nor planar information. Without this information, going forward, our gfx
testing is going to break. It would be great if we had access to higher
level buffer structs (like gbm), but we generally don't since they would be
created by other apps (chrome browser, android apps, etc...).
> > Also modifies *_fb_create_handle() calls to accept a
> > format_plane_index so that handles for each plane can be generated.
> > Previously, many *_fb_create_handle() calls simply defaulted to plane 0
> > only.
>
> And with this patch the amd/amdgpu, armada, gma500, i915, mediatek, msm,
> nouveau and radeon drivers still do. Do none of them support multi-planar
> formats ?
>
> I would imagine that some of these do support multi-planar formats, but
they don't appear to have them implemented yet (except perhaps as offsets
into a single buffer). I will certainly be looking into this soon, but any
changes will come in future patches.
> > Signed-off-by: Joe Kniss <djmk at google.com>
> > ---
> > drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 5 +-
> > drivers/gpu/drm/armada/armada_fb.c | 1 +
> > drivers/gpu/drm/drm_crtc_internal.h | 2 +
> > drivers/gpu/drm/drm_fb_cma_helper.c | 11 ++--
> > drivers/gpu/drm/drm_framebuffer.c | 79
> +++++++++++++++++++++++++-
> > drivers/gpu/drm/drm_ioctl.c | 1 +
> > drivers/gpu/drm/exynos/exynos_drm_fb.c | 7 ++-
> > drivers/gpu/drm/gma500/framebuffer.c | 2 +
> > drivers/gpu/drm/i915/intel_display.c | 1 +
> > drivers/gpu/drm/mediatek/mtk_drm_fb.c | 1 +
> > drivers/gpu/drm/msm/msm_fb.c | 5 +-
> > drivers/gpu/drm/nouveau/nouveau_display.c | 1 +
> > drivers/gpu/drm/omapdrm/omap_fb.c | 5 +-
> > drivers/gpu/drm/radeon/radeon_display.c | 5 +-
> > drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 6 ++-
> > drivers/gpu/drm/tegra/fb.c | 9 +++-
> > include/drm/drm_framebuffer.h | 1 +
> > include/uapi/drm/drm.h | 2 +
> > 18 files changed, 127 insertions(+), 17 deletions(-)
>
> [snip]
>
> > diff --git a/drivers/gpu/drm/drm_framebuffer.c
> > b/drivers/gpu/drm/drm_framebuffer.c index 28a0108a1ab8..67b3be1bedbc
> 100644
> > --- a/drivers/gpu/drm/drm_framebuffer.c
> > +++ b/drivers/gpu/drm/drm_framebuffer.c
> > @@ -24,6 +24,7 @@
> > #include <drm/drmP.h>
> > #include <drm/drm_auth.h>
> > #include <drm/drm_framebuffer.h>
> > +#include <drm/drm_gem.h>
> >
> > #include "drm_crtc_internal.h"
>
> [snip]
>
> > +/**
> > + * drm_mode_getfb2 - get FB info
> > + * @dev: drm device for the ioctl
> > + * @data: data pointer for the ioctl
> > + * @file_priv: drm file for the ioctl call
> > + *
> > + * Lookup the FB given its ID and return info about it.
> > + *
> > + * Called by the user via ioctl.
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int drm_mode_getfb2(struct drm_device *dev,
> > + void *data, struct drm_file *file_priv)
> > +{
> > + struct drm_mode_fb_cmd2 *r = data;
> > + struct drm_framebuffer *fb;
> > + int ret, i;
> > +
> > + if (!drm_core_check_feature(dev, DRIVER_MODESET))
> > + return -EINVAL;
> > +
> > + fb = drm_framebuffer_lookup(dev, r->fb_id);
> > + if (!fb)
> > + return -ENOENT;
> > +
> > + r->height = fb->height;
> > + r->width = fb->width;
> > + r->pixel_format = fb->format->format;
> > + for (i = 0; i < 4; ++i) {
> > + r->pitches[i] = fb->pitches[i];
> > + r->offsets[i] = fb->offsets[i];
> > + r->modifier[i] = fb->modifier;
> > + r->handles[i] = 0;
> > + }
> > +
> > + for (i = 0; i < fb->format->num_planes; ++i) {
> > + if (fb->funcs->create_handle) {
> > + if (drm_is_current_master(file_priv) ||
> > + capable(CAP_SYS_ADMIN) ||
> > + drm_is_control_client(file_priv)) {
> > + ret = fb->funcs->create_handle(fb, i,
> > file_priv,
> > +
> > &r->handles[i]);
> > + if (ret)
> > + break;
> > + } else {
> > + /* GET_FB() is an unprivileged ioctl so we
> > must
> > + * not return a buffer-handle to non-master
> > + * processes! For backwards-compatibility
> > + * reasons, we cannot make GET_FB()
> > privileged,
> > + * so just return an invalid handle for
> > + * non-masters. */
>
> There's no backward compatibility to handle here, just make it privileged
> if
> it has to be.
>
> Sure thing, sounds good.
> > + r->handles[i] = 0;
> > + ret = 0;
> > + }
> > + } else {
> > + ret = -ENODEV;
> > + break;
> > + }
> > + }
> > +
> > + /* If handle creation failed, delete/dereference any that were
> made.
> */
> > + if (ret) {
> > + for (i = 0; i < 4; ++i) {
> > + if (r->handles[i])
> > + drm_gem_handle_delete(file_priv, r-
> >handles[i]);
>
> My initial reaction to this was to reply that not all drivers use GEM, but
> after some investigation it seems they actually do. If that's really the
> case,
> we could get rid of the .create_handle() operation completely, which should
> simplify the implementation of both DRM_IOCTL_MODE_GETFB and
> DRM_IOCTL_MODE_GETFB2.
>
> Deleting the handle is the same in all cases, but creating the handle
isn't consistent across the drivers. I didn't see a clean way to simplify
this.
> > + r->handles[i] = 0;
> > + }
> > + }
> > +
> > + drm_framebuffer_unreference(fb);
> > +
> > + return ret;
> > +}
>
> [snip]
>
> > diff --git a/drivers/gpu/drm/omapdrm/omap_fb.c
> > b/drivers/gpu/drm/omapdrm/omap_fb.c index 29dc677dd4d3..a982c72a773e
> 100644
> > --- a/drivers/gpu/drm/omapdrm/omap_fb.c
> > +++ b/drivers/gpu/drm/omapdrm/omap_fb.c
> > @@ -90,12 +90,15 @@ struct omap_framebuffer {
> > };
> >
> > static int omap_framebuffer_create_handle(struct drm_framebuffer *fb,
> > + unsigned int format_plane_index,
> > struct drm_file *file_priv,
> > unsigned int *handle)
> > {
> > struct omap_framebuffer *omap_fb = to_omap_framebuffer(fb);
> > + if (format_plane_index >= 4 || !omap_fb->planes[format_plane_
> index])
>
> The first check shouldn't be needed, the core should never call this
> operation
> with an index >= 4.
>
> I'll remove the check then.
> > + return -ENOENT;
> > return drm_gem_handle_create(file_priv,
> > - omap_fb->planes[0].bo, handle);
> > + omap_fb->planes[format_plane_index].bo, handle);
> > }
>
> [snip]
>
> > diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> > index b2c52843bc70..c81c75335cca 100644
> > --- a/include/uapi/drm/drm.h
> > +++ b/include/uapi/drm/drm.h
> > @@ -814,6 +814,8 @@ extern "C" {
> > #define DRM_IOCTL_MODE_CREATEPROPBLOB DRM_IOWR(0xBD, struct
> > drm_mode_create_blob)
> > #define DRM_IOCTL_MODE_DESTROYPROPBLOB DRM_IOWR(0xBE, struct
> > drm_mode_destroy_blob)
> >
> > +#define DRM_IOCTL_MODE_GETFB2 DRM_IOWR(0xC4, struct drm_mode_fb_cmd2)
> > +
>
> Which tree is this based on ? The last defined ioctl
> (DRM_IOCTL_SYNCOBJ_FD_TO_HANDLE) is 0xC2 in drm-next and drm-misc-next.
>
> I just did a quick search for "DRM_IOWR 0xC*" and picked the first unused
one, there was a patch in-flight from last month that used 0xC3 (
https://lists.freedesktop.org/archives/amd-gfx/2017-June/010153.html).
Naturally, I'll set this to whatever is appropriate.
> > /**
> > * Device specific ioctls should only be in their respective headers
> > * The device specific ioctl range is from 0x40 to 0x9f.
>
> --
> Regards,
>
> Laurent Pinchart
>
>
Thanks!
-j
--
Dr. Joe Michael Kniss | Google ChromeOS | djmk at google.com |
1-801-898-7977 <(801)%20898-7977>
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