drm/tegra: gem: Add a clarifying comment

Clarify when a fixed IOV address can be used and when a buffer has to
be mapped before the IOVA can be used.

Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Thierry Reding 2021-03-26 15:51:36 +01:00
parent 4def888d41
commit 476e93205f
1 changed files with 8 additions and 0 deletions

View File

@ -119,6 +119,14 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
dma_addr_t phys_addr, *phys;
struct sg_table *sgt;
/*
* If we're not attached to a domain, we already stored the
* physical address when the buffer was allocated. If we're
* part of a group that's shared between all display
* controllers, we've also already mapped the framebuffer
* through the SMMU. In both cases we can short-circuit the
* code below and retrieve the stored IOV address.
*/
if (!domain || dc->client.group)
phys = &phys_addr;
else