[PATCH v2 0/8] Add new formats support to vkms

[Igor Torrente]

Hi Pekka,

On Tue, Nov 9, 2021 at 6:32 AM Pekka Paalanen <ppaalanen at gmail.com> wrote:
>
> On Tue, 26 Oct 2021 08:34:00 -0300
> Igor Torrente <igormtorrente at gmail.com> wrote:
>
> > Summary
> > =======
> > This series of patches refactor some vkms components in order to introduce
> > new formats to the planes and writeback connector.
> >
> > Now in the blend function, the plane's pixels are converted to ARGB16161616
> > and then blended together.
> >
> > The CRC is calculated based on the ARGB1616161616 buffer. And if required,
> > this buffer is copied/converted to the writeback buffer format.
> >
> > And to handle the pixel conversion, new functions were added to convert
> > from a specific format to ARGB16161616 (the reciprocal is also true).
> >
> > Tests
> > =====
> > This patch series was tested using the following igt tests:
> > -t ".*kms_plane.*"
> > -t ".*kms_writeback.*"
> > -t ".*kms_cursor_crc*"
> > -t ".*kms_flip.*"
> >
> > New tests passing
> > -------------------
> > - pipe-A-cursor-size-change
> > - pipe-A-cursor-alpha-transparent
> >
> > Performance
> > -----------
> > Following some optimization proposed by Pekka Paalanen, now the code
> > runs way faster than V1 and slightly faster than the current implementation.
> >
> > |                          Frametime                          |
> > |:---------------:|:---------:|:--------------:|:------------:|
> > |  implmentation  |  Current  |  Per-pixel(V1) | Per-line(V2) |
> > | frametime range |  8~22 ms  |    32~56 ms    |    6~19 ms   |
> > |     Average     |  10.0 ms  |     35.8 ms    |    8.6 ms    |
>
> Wow, that's much better than I expected.
>
> What is your benchmark? That is, what program do you use and what
> operations does it trigger to produce these measurements? What are the
> sizes of all the planes/buffers involved? What kind of CPU was this ran
> on?

1 and 2) I just measured the frametime of the IGT test ".*kms_cursor_crc*"
using jiffies. I Collected all the frametimes, put all of them into a
spreadsheet, calculated some values and drew some histograms.

I mean, it is not the best benchmark, but at least give an idea of what
is happening.

3) The primary plane was 1024x768, but the cursor plane
varies between the tests. All XRGB_8888, if I'm not mistaken.

4) I tested it on a Qemu VM running on the Intel core i5 4440. ~3.3GHz

>
>
> Thanks,
> pq
>
> >
> > Writeback test
> > --------------
> > During the development of this patch series, I discovered that the
> > writeback-check-output test wasn't filling the plane correctly.
> >
> > So, currently, this patch series is failing in this test. But I sent a
> > patch to igt to fix it[1].
> >
> > XRGB to ARGB behavior
> > =====================
> > During the development, I decided to always fill the alpha channel of
> > the output pixel whenever the conversion from a format without an alpha
> > channel to ARGB16161616 is necessary. Therefore, I ignore the value
> > received from the XRGB and overwrite the value with 0xFFFF.
> >
> > ---
> > Igor Torrente (8):
> >   drm: vkms: Replace the deprecated drm_mode_config_init
> >   drm: vkms: Alloc the compose frame using vzalloc
> >   drm: vkms: Replace hardcoded value of `vkms_composer.map` to
> >     DRM_FORMAT_MAX_PLANES
> >   drm: vkms: Add fb information to `vkms_writeback_job`
> >   drm: drm_atomic_helper: Add a new helper to deal with the writeback
> >     connector validation
> >   drm: vkms: Refactor the plane composer to accept new formats
> >   drm: vkms: Exposes ARGB_1616161616 and adds XRGB_16161616 formats
> >   drm: vkms: Add support to the RGB565 format
> >
> >  drivers/gpu/drm/drm_atomic_helper.c   |  47 ++++
> >  drivers/gpu/drm/vkms/vkms_composer.c  | 329 +++++++++++++++-----------
> >  drivers/gpu/drm/vkms/vkms_drv.c       |   6 +-
> >  drivers/gpu/drm/vkms/vkms_drv.h       |  14 +-
> >  drivers/gpu/drm/vkms/vkms_formats.h   | 252 ++++++++++++++++++++
> >  drivers/gpu/drm/vkms/vkms_plane.c     |  17 +-
> >  drivers/gpu/drm/vkms/vkms_writeback.c |  33 ++-
> >  include/drm/drm_atomic_helper.h       |   3 +
> >  8 files changed, 545 insertions(+), 156 deletions(-)
> >  create mode 100644 drivers/gpu/drm/vkms/vkms_formats.h
> >
>