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| author | Marijn Suijten <marijn.suijten@somainline.org> | 2023-09-09 10:26:33 +0200 |
|---|---|---|
| committer | Marijn Suijten <marijn.suijten@somainline.org> | 2023-09-09 11:07:56 +0200 |
| commit | 64b09cef49f9cd7e7eb9871d8fe36ed5b315149a (patch) | |
| tree | fb15682bcf5ecfaf3c9beea6856c284939b2d4b8 | |
| parent | b709c3010e9a39b7ed4ed63a16148d4fa0055d3f (diff) | |
| download | libdrm-64b09cef49f9cd7e7eb9871d8fe36ed5b315149a.tar.gz libdrm-64b09cef49f9cd7e7eb9871d8fe36ed5b315149a.tar.bz2 libdrm-64b09cef49f9cd7e7eb9871d8fe36ed5b315149a.zip | |
modetest: document why no blob is created for linear gamma LUT
As found and discussed in [MR 58] a blob is not created in the else arm
because adding the GAMMA_LUT property with a NULL/0 blob_id causes it
to be reset to a default linear / pass-thru gamma table. The values
in the gamma_lut table might still be consumed in the legacy API path
below though, so it has to be initialized to a linear table.
[MR 58]: https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/58#note_466972
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
| -rw-r--r-- | tests/modetest/modetest.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/tests/modetest/modetest.c b/tests/modetest/modetest.c index 3d24e0dc..8bc3d5a5 100644 --- a/tests/modetest/modetest.c +++ b/tests/modetest/modetest.c @@ -1158,6 +1158,11 @@ static void set_gamma(struct device *dev, unsigned crtc_id, unsigned fourcc) util_smpte_c8_gamma(256, gamma_lut); drmModeCreatePropertyBlob(dev->fd, gamma_lut, sizeof(gamma_lut), &blob_id); } else { + /* + * Initialize gamma_lut to a linear table for the legacy API below. + * The modern property API resets to a linear/pass-thru table if blob_id + * is 0, hence no PropertyBlob is created here. + */ for (i = 0; i < 256; i++) { gamma_lut[i].red = gamma_lut[i].green = |