Merge tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-mediagrafted

Pull media updates from Mauro Carvalho Chehab:

 - v4l2-core: added ISP statistics support and per-block validation

 - v4l2-core: Allow unknown HDR10 white point and luminance

 - New camera sensors: Sony IMX678 and IMX471m, Himax HM1092 IR sensor

 - New codec: Milos: VPU v2.0 codec support

 - isp driver: gained support for Dreamchip RPPX1 ISP framework

 - vsp1 driver: gained support for RZ/T2H and RZ/N2H

 - Novalake driver: gained CVS support for new NVL hardware

 - dvb-core: fix feed leak on failed DMX_ADD_PID

 - several driver fixes, cleanups and minor improvements

* tag 'media/v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (308 commits)
  media: ipu-bridge: check all DMI entries when overriding sensor rotation
  media: v4l2-async: avoid deleting unlinked ASC entry on link error
  media: rzg2l-cru: Align bytesperline to hardware DMA stride requirement
  media: intel/ipu6: fix async notifier cleanup leak on parse error
  media: staging/ipu7: fix async notifier UAF on probe error path
  media: amd: isp4: fix self-deadlock in isp4sd_pwron_and_init() error path
  media: amd: isp4: release partial allocations in isp4if_alloc_fw_gpumem()
  media: rcar-isp: Fix VSPX reference leaks
  media: rcar-isp: Release ISPCORE resources
  media: i2c: imx415: Release runtime PM reference on VBLANK error
  media: i2c: imx415: Return test pattern write errors
  media: renesas: vsp1: Declare index variables in for loop statement
  media: renesas: vsp1: Make reset control optional to support platforms without a reset line
  media: dt-bindings: media: renesas,vsp1: Document RZ/T2H and RZ/N2H SoCs
  media: dt-bindings: media: renesas,fcp: Document RZ/T2H and RZ/N2H SoCs
  media: nxp: imx8-isi: Add additional 32-bit RGB format support
  media: nxp: imx8-isi: Add 16-bit raw Bayer format support
  media: nxp: imx8-isi: Implement per-stream reference counting for multiplexed streams
  media: nxp: imx8-isi: Use BIT_ULL() for 64-bit stream masks
  media: nxp: imx8-isi: Correct color map between V4L2 and ISI
  ...

1 files changed, 73 insertions, 0 deletions

diff --git a/tools/include/uapi/README b/tools/include/uapi/README
new file mode 100644
index 000000000..7147b1b2c
--- /dev/null
+++ b/tools/include/uapi/README
@@ -0,0 +1,73 @@
+Why we want a copy of kernel headers in tools?
+==============================================
+
+There used to be no copies, with tools/ code using kernel headers
+directly. From time to time tools/perf/ broke due to legitimate kernel
+hacking. At some point Linus complained about such direct usage. Then we
+adopted the current model.
+
+The way these headers are used in perf are not restricted to just
+including them to compile something.
+
+There are sometimes used in scripts that convert defines into string
+tables, etc, so some change may break one of these scripts, or new MSRs
+may use some different #define pattern, etc.
+
+E.g.:
+
+  $ ls -1 tools/perf/trace/beauty/*.sh | head -5
+  tools/perf/trace/beauty/arch_errno_names.sh
+  tools/perf/trace/beauty/drm_ioctl.sh
+  tools/perf/trace/beauty/fadvise.sh
+  tools/perf/trace/beauty/fsconfig.sh
+  tools/perf/trace/beauty/fsmount.sh
+  $
+  $ tools/perf/trace/beauty/fadvise.sh
+  static const char *fadvise_advices[] = {
+        [0] = "NORMAL",
+        [1] = "RANDOM",
+        [2] = "SEQUENTIAL",
+        [3] = "WILLNEED",
+        [4] = "DONTNEED",
+        [5] = "NOREUSE",
+  };
+  $
+
+The tools/perf/check-headers.sh script, part of the tools/ build
+process, points out changes in the original files.
+
+So its important not to touch the copies in tools/ when doing changes in
+the original kernel headers, that will be done later, when
+check-headers.sh inform about the change to the perf tools hackers.
+
+Another explanation from Ingo Molnar:
+It's better than all the alternatives we tried so far:
+
+ - Symbolic links and direct #includes: this was the original approach but
+   was pushed back on from the kernel side, when tooling modified the
+   headers and broke them accidentally for kernel builds.
+
+ - Duplicate self-defined ABI headers like glibc: double the maintenance
+   burden, double the chance for mistakes, plus there's no tech-driven
+   notification mechanism to look at new kernel side changes.
+
+What we are doing now is a third option:
+
+ - A software-enforced copy-on-write mechanism of kernel headers to
+   tooling, driven by non-fatal warnings on the tooling side build when
+   kernel headers get modified:
+
+    Warning: Kernel ABI header differences:
+      diff -u tools/include/uapi/drm/i915_drm.h include/uapi/drm/i915_drm.h
+      diff -u tools/include/uapi/linux/fs.h include/uapi/linux/fs.h
+      diff -u tools/include/uapi/linux/kvm.h include/uapi/linux/kvm.h
+      ...
+
+   The tooling policy is to always pick up the kernel side headers as-is,
+   and integate them into the tooling build. The warnings above serve as a
+   notification to tooling maintainers that there's changes on the kernel
+   side.
+
+We've been using this for many years now, and it might seem hacky, but
+works surprisingly well.
+