On 08/24/2015 02:42 PM, Thomas Hellstrom wrote:
On 08/24/2015 07:12 PM, Daniel Stone wrote:
Hi,
On 24 August 2015 at 18:10, Thomas Hellstrom thellstrom@vmware.com wrote:
On 08/24/2015 07:04 PM, Daniel Stone wrote:
On 24 August 2015 at 17:56, Thomas Hellstrom thellstrom@vmware.com wrote:
On 08/24/2015 05:52 PM, Daniel Stone wrote:
I still don't think this ameliorates the need for batching: consider the case where you update two disjoint screen regions and want them both flushed. Either you issue two separate sync calls (which can be disadvantageous performance-wise on some hardware / setups), or you accumulate the regions and only flush later. So either two ioctls (one in the style of dirtyfb and one to perform the sync/flush; you can shortcut to assume the full buffer was damaged if the former is missing), or one like this:
struct dma_buf_sync_2d { enum dma_buf_sync_flags flags;
__u64 stride_bytes; __u32 bytes_per_pixel; __u32 num_regions; struct { __u64 x; __u64 y; __u64 width; __u64 height; } regions[];};
Fine with me, although perhaps bytes_per_pixel is a bit redundant?
Redundant how? It's not implicit in stride.
For flushing purposes, isn't it possible to cover all cases by assuming bytes_per_pixel=1? Not that it matters much.
Sure, though in that case best to replace x with line_byte_offset or something, because otherwise I guarantee you everyone will get it wrong, and it'll be a pain to track down. Like how I managed to misread it now. :)
OK, yeah you have a point. IMO let's go for your proposal.
Tiago, is this OK with you?
yup, I think so. So IIUC the main changes needed for the drivers implement 2D sync lies in the dma_buf_sync_2d structure only. I.e. there's nothing really to be changed in the common code, right? Then I'll just need to stick somewhere the logic about making sync mandatory, which I couldn't conclude much from your discussions with Jerome et al. I'll need to investigate more here.
Also, I still want to iterate with Google policy team about the actual need for a syscall. But I believe that eventually could be an secondary phase of this work (in case we ever agree upon having that).
Tiago