SPI Engine: SDO data prefetch #1501
Open
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This was referenced Oct 31, 2024
LBFFilho
force-pushed
the
spi_sdo_prefetch
branch
5 times, most recently
from
188d0a7
to
1840af0
Compare
LBFFilho
force-pushed
the
spi_sdo_prefetch
branch
from
1840af0
to
e6937d4
Compare
Switched SDO source control to software (memory-mapped register). SDO data can now be clocked in independently from the offload trigger. This allows lower latencies for executing transfers, since the data can be obtained from the DMA before the trigger. It also better separates the command path from the data path Signed-off-by: Laez Barbosa <[email protected]>
LBFFilho
force-pushed
the
spi_sdo_prefetch
branch
from
e6937d4
to
4f982aa
Compare
LBFFilho
requested review from
IuliaCMoldovan,
gastmaier,
StancaPop,
podgori and
ladace
as code owners
gastmaier
reviewed
Nov 19, 2024
| [31:0] 0x00000000 | ||
| OFFLOAD0_SDO_SRC_SEL | ||
| RW | ||
| Selects data source for SDO offload. 0=SDO memory, 1=SDO stream (DMA). |
There was a problem hiding this comment.
Selects data source for SDO offload. 0=Memory Mapped, 1=Streaming.
dlech
reviewed
Nov 20, 2024
| @@ -447,6 +447,21 @@ ENDFIELD | |||
| ############################################################################################ | |||
| ############################################################################################ | |||
|
|
|||
| REG | |||
| 0x43 | |||
| OFFLOAD0_SDO_SRC_SEL | |||
There was a problem hiding this comment.
I already submitted patches to upstream Linux assuming that this was a compile time option instead of a runtime option. So if we are going to change this, I need to retract the changes in that patch.
However, having the setting globally like this instead of per transfer isn't as useful since it would limit a SPI offload to either using one or the other. We could never have a SPI message that does both types of TX transfers. So I would be OK if we just left this as a compile time option for now.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
PR Description
Allows spi_engine_execution get sdo data independently of the instruction command. This reduces the trigger to transfer latency, and opens the door to further pipelining this path or reducing latency even more.
Also changes SDO source to be software-controlled, through a new register.
(this PR should be merged after #1499)
PR Type
PR Checklist