Hi Ben,
On 3 May 2017 at 06:14, Ben Widawsky <ben@xxxxxxxxxxxx> wrote:
> +struct drm_format_modifier_blob {
> +#define FORMAT_BLOB_CURRENT 1
> + /* Version of this blob format */
> + u32 version;
> +
> + /* Flags */
> + u32 flags;
> +
> + /* Number of fourcc formats supported */
> + u32 count_formats;
> +
> + /* Where in this blob the formats exist (in bytes) */
> + u32 formats_offset;
> +
> + /* Number of drm_format_modifiers */
> + u32 count_modifiers;
> +
> + /* Where in this blob the modifiers exist (in bytes) */
> + u32 modifiers_offset;
> +
> + /* u32 formats[] */
> + /* struct drm_format_modifier modifiers[] */
> +} __packed;
> +
Why do we need packing here? Both layout and member offsets are
identical with and w/o it.
If there's something subtle to it, please add a comment.
> +static int create_in_format_blob(struct drm_device *dev, struct drm_plane *plane,
> + const struct drm_plane_funcs *funcs,
> + const uint32_t *formats, unsigned int format_count,
> + const uint64_t *format_modifiers)
> +{
> + blob_size = ALIGN(sizeof(struct drm_format_modifier_blob), 8);
> + blob_size += ALIGN(formats_size, 8);
The 8 is "sizeof(void *) isn't it? Shouldn't we use that instead since
it expands to 4 for 32bit systems?
> + blob_size += modifiers_size;
> +
> + blob = drm_property_create_blob(dev, blob_size, NULL);
> + if (IS_ERR(blob))
> + return -1;
> +
> + blob_data = (struct drm_format_modifier_blob *)blob->data;
> + blob_data->version = FORMAT_BLOB_CURRENT;
> + blob_data->count_formats = format_count;
> + blob_data->formats_offset = sizeof(struct drm_format_modifier_blob);
Shouldn't we reuse the ALIGN(...) from above?
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index 8c67fc03d53d..dcdd04c55792 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -665,6 +665,32 @@ struct drm_mode_atomic {
> __u64 user_data;
> };
>
> +struct drm_format_modifier {
> + /* Bitmask of formats in get_plane format list this info applies to. The
> + * offset allows a sliding window of which 64 formats (bits).
> + *
> + * Some examples:
> + * In today's world with < 65 formats, and formats 0, and 2 are
> + * supported
> + * 0x0000000000000005
> + * ^-offset = 0, formats = 5
> + *
> + * If the number formats grew to 128, and formats 98-102 are
> + * supported with the modifier:
> + *
> + * 0x0000003c00000000 0000000000000000
> + * ^
> + * |__offset = 64, formats = 0x3c00000000
> + *
> + */
> + uint64_t formats;
> + uint32_t offset;
> + uint32_t pad;
> +
> + /* This modifier can be used with the format for this plane. */
> + uint64_t modifier;
> +} __packed;
> +
As above - why __packed?
Regards,
Emil
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