[PATCH v4 2/9] drm/exynos: ipp: Add IPP v2 framework

[Tobias Jakobi]

Dave Airlie wrote:
> On 23 October 2017 at 17:54, Marek Szyprowski <m.szyprowski at samsung.com> wrote:
>> This patch adds Exynos IPP v2 subsystem and userspace API.
>>
>> New userspace API is focused ONLY on memory-to-memory image processing.
>> The two remainging IPP operation modes (framebuffer writeback and
>> local-path output with image processing) can be implemented using
>> standard DRM features: writeback connectors and additional DRM planes with
>> scaling features.
>>
>> V2 IPP userspace API is not compatible with old IPP ioctls. This is a
>> significant change, but the old IPP subsystem in mainline Linux kernel was
>> partially disfunctional anyway and not used in any open-source project.
>>
>> V2 IPP userspace API is based on stateless approach, which much better fits
>> to memory-to-memory image processing model. It also provides support for
>> all image formats, which are both already defined in DRM API and supported
>> by the existing IPP hardware modules.
>>
>> The API consists of the following ioctls:
>> - DRM_IOCTL_EXYNOS_IPP_GET_RESOURCES: to enumerate all available image
>>   processing modules,
>> - DRM_IOCTL_EXYNOS_IPP_GET_CAPS: to query capabilities and supported image
>>   formats of given IPP module,
>> - DRM_IOCTL_EXYNOS_IPP_GET_LIMITS: to query hardware limitiations for
>>   selected image format of given IPP module,
>> - DRM_IOCTL_EXYNOS_IPP_COMMIT: to perform operation described by the
>>   provided structures (source and destination buffers, operation rectangle,
>>   transformation, etc).
>>
>> The proposed userspace API is extensible. In the future more advanced image
>> processing operations can be defined to support for example blending.
>>
>> Userspace API is fully functional also on DRM render nodes, so it is not
>> limited to the root/privileged client.
>>
>> Internal driver API also has been completely rewritten. New IPP core
>> performs all possible input validation, checks and object life-time
>> control. The drivers can focus only on writing configuration to hardware
>> registers. Stateless nature of DRM_IOCTL_EXYNOS_IPP_COMMIT ioctl simplifies
>> the driver API. Minimal driver needs to provide a single callback for
>> starting processing and an array with supported image formats.
> 
> Is there userspace user for this? This is pretty significant
> driver-specific API addition.
> 
> The commit should contain pointers to a userspace project using this,
> or patches to one.
The pointers are in the cover letter of the series.

- Tobias

> Dave.
>