On Thu, Apr 19, 2018 at 3:54 PM, Aaron Durbin adurbin@google.com wrote:
OK. It's just moving code around.
Yeah, I just want to shuffle code around. Nothing is broken right now, it's just working in a confusing and inconsistent way. We should have an API where the callbacks share the same semantics across all implementations (and also document those semantics more clearly).
I can send some CLs out.
While you guys are at it, it might be worth folding spi_claim_bus() and spi_release_bus() into these changes so that CS is managed automatically for things like SPI flash transactions. Right now they return 0 for controllers that don't define ctrlr->claim_bus and ctrlr->release_bus, meaning those which do fused ops and might not even allow the user to manually drive CS. In those cases the behavior feels like silent failure since they don't even attempt to do the thing the user asked, yet they are required to be in the common codepaths for generic SPI controllers.
The result would be that functions such as do_spi_flash_cmd() no longer need to explicitly manage CS by claiming/releasing the SPI bus. On the other hand, one might want to transfer one or more vectors without toggling CS, so we may need to expose a way to leave CS alone e.g. thru struct spi_op or another function parameter.
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David Hendricks