[PATCHv3 01/10] drm/crtc: Add histogram properties

[Murthy, Arun R]

> On Tue, Dec 10, 2024 at 05:52:38PM +0000, Murthy, Arun R wrote:
> > > On Tue, Dec 10, 2024 at 08:42:36AM +0000, Murthy, Arun R wrote:
> > > > > On Mon, Dec 09, 2024 at 09:54:55PM +0530, Arun R Murthy wrote:
> > > > > > Add variables for histogram drm_property, its corrsponding
> > > > > > crtc_state variables and define the structure pointed by the blob
> property.
> > > > > >
> > > > > > struct drm_histogram and drm_iet defined in
> > > > > > include/uapi/drm/drm_mode.h
> > > > > >
> > > > > > The property HISTOGRAM_ENABLE allows user to enable/disable
> > > > > > the histogram feature in the hardware. Upon KMD enabling by
> > > > > > writing to the hardware registers, a histogram is generated.
> > > > > > Histogram is composed of 'n' bins with each bin being an integer(pixel
> count).
> > > > >
> > > > > Is it really a count of pixels that fall into one of the bins?
> > > > It's the statistics generated for each frame that is sent to the
> > > > display and the
> > > value corresponds to 5 bit pixel depth.
> > >
> > > Let me try it once more, but this is becoming tiresome. Please
> > > provide a description of the property good enough so that one can
> > > implement HISTOGRAM support for the VKMS driver. You don't have to
> > > provide Intel- specific details, but the description should be complete
> enough.
> > > "The number of pixels falling into each of the bins, sorted by
> > > luminosity, started from the brighest ones" might be an example of a good
> enough desription.
> > > Then one can add such functionality to other drivers. Just saying "statistics"
> > > doesn't give us anything.
> > >
> > This is a hardware feature and hence for other drivers to add support
> > for this means that the hardware should have support for this.
> 
> OpenGL, OpenGL ES, Vulkan and other libraries also define software interface
> for hardware features. However they define it in a way that allows at least
> software implementation. I'm not arguing about the particular feature or its
> implementation. I'm not asking for the _hardware_ description or any other
> kind hardware-related information.
> But I really want to see a good documentation for the userspace interface that
> will allows other vendors to implement it in their drivers (including my
> example, VKMS). Up to now I have not seen a definition of properties that fits
> this criteria.
> 
> > Each bin consists of 5 bit pixel depth.
> > Example code of how to use this histogram and increase the contrast is GHE.
> 
> Yes, I have taken a look. No, it's not a replacement for the documentation.
> 
> I'm really sorry to write that, but until the documentation issue is resolved,
> please consider this patch to be:
> 
> Nacked-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> 
Hi Dmitry,

I have pushed a new version of the DPST core patches that includes drm-core
changes and the documentation for the new uapi and the blob structures
exposed to the user.
Please let me know for any further documentation to be added?
New patch pushed @ https://patchwork.freedesktop.org/series/135793/

Thanks and Regards,
Arun R Murthy
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