From 3c8861d84a4d2c6cd7221d18e49bf9201c6c6115 Mon Sep 17 00:00:00 2001 From: Matt Roper Date: Mon, 17 Dec 2018 14:44:14 -0800 Subject: [PATCH] drm: Add color management LUT validation helper (v4) MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Some hardware may place additional restrictions on the gamma/degamma curves described by our LUT properties. E.g., that a gamma curve never decreases or that the red/green/blue channels of a LUT's entries must be equal. Let's add a helper function that drivers can use to test that a userspace-provided LUT is valid and doesn't violate hardware requirements. v2: - Combine into a single helper that just takes a bitmask of the tests to apply. (Brian Starkey) - Add additional check (always performed) that LUT property blob size is always a multiple of the LUT entry size. (stolen from ARM driver) v3: - Drop the LUT size check again since drm_atomic_replace_property_blob_from_id() already covers this for us. (Alexandru Gheorghe) v4: - Use an enum to describe possible test values rather than #define's; this is cleaner to provide kerneldoc for. (Daniel Vetter) - s/DRM_COLOR_LUT_INCREASING/DRM_COLOR_LUT_NON_DECREASING/. (Ville) Cc: Uma Shankar Cc: Swati Sharma Cc: Brian Starkey Cc: Daniel Vetter Cc: Ville Syrjälä Signed-off-by: Matt Roper Reviewed-by: Brian Starkey Reviewed-by: Alexandru Gheorghe Reviewed-by: Uma Shankar Acked-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181217224415.12848-1-matthew.d.roper@intel.com --- drivers/gpu/drm/drm_color_mgmt.c | 44 ++++++++++++++++++++++++++++++++++++++++ include/drm/drm_color_mgmt.h | 29 ++++++++++++++++++++++++++ 2 files changed, 73 insertions(+) diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c index 07dcf47..968ca7c 100644 --- a/drivers/gpu/drm/drm_color_mgmt.c +++ b/drivers/gpu/drm/drm_color_mgmt.c @@ -462,3 +462,47 @@ int drm_plane_create_color_properties(struct drm_plane *plane, return 0; } EXPORT_SYMBOL(drm_plane_create_color_properties); + +/** + * drm_color_lut_check - check validity of lookup table + * @lut: property blob containing LUT to check + * @tests: bitmask of tests to run + * + * Helper to check whether a userspace-provided lookup table is valid and + * satisfies hardware requirements. Drivers pass a bitmask indicating which of + * the tests in &drm_color_lut_tests should be performed. + * + * Returns 0 on success, -EINVAL on failure. + */ +int drm_color_lut_check(struct drm_property_blob *lut, + uint32_t tests) +{ + struct drm_color_lut *entry; + int i; + + if (!lut || !tests) + return 0; + + entry = lut->data; + for (i = 0; i < drm_color_lut_size(lut); i++) { + if (tests & DRM_COLOR_LUT_EQUAL_CHANNELS) { + if (entry[i].red != entry[i].blue || + entry[i].red != entry[i].green) { + DRM_DEBUG_KMS("All LUT entries must have equal r/g/b\n"); + return -EINVAL; + } + } + + if (i > 0 && tests & DRM_COLOR_LUT_NON_DECREASING) { + if (entry[i].red < entry[i - 1].red || + entry[i].green < entry[i - 1].green || + entry[i].blue < entry[i - 1].blue) { + DRM_DEBUG_KMS("LUT entries must never decrease.\n"); + return -EINVAL; + } + } + } + + return 0; +} +EXPORT_SYMBOL(drm_color_lut_check); diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h index 90ef999..6affbda 100644 --- a/include/drm/drm_color_mgmt.h +++ b/include/drm/drm_color_mgmt.h @@ -69,4 +69,33 @@ int drm_plane_create_color_properties(struct drm_plane *plane, u32 supported_ranges, enum drm_color_encoding default_encoding, enum drm_color_range default_range); + +/** + * enum drm_color_lut_tests - hw-specific LUT tests to perform + * + * The drm_color_lut_check() function takes a bitmask of the values here to + * determine which tests to apply to a userspace-provided LUT. + */ +enum drm_color_lut_tests { + /** + * @DRM_COLOR_LUT_EQUAL_CHANNELS: + * + * Checks whether the entries of a LUT all have equal values for the + * red, green, and blue channels. Intended for hardware that only + * accepts a single value per LUT entry and assumes that value applies + * to all three color components. + */ + DRM_COLOR_LUT_EQUAL_CHANNELS = BIT(0), + + /** + * @DRM_COLOR_LUT_NON_DECREASING: + * + * Checks whether the entries of a LUT are always flat or increasing + * (never decreasing). + */ + DRM_COLOR_LUT_NON_DECREASING = BIT(1), +}; + +int drm_color_lut_check(struct drm_property_blob *lut, + uint32_t tests); #endif -- 2.7.4