On 14-01-21, 01:20, mdalam@xxxxxxxxxxxxxx wrote: > On 2021-01-12 15:40, Vinod Koul wrote: > > On 12-01-21, 15:01, mdalam@xxxxxxxxxxxxxx wrote: > > > On 2020-12-21 23:03, mdalam@xxxxxxxxxxxxxx wrote: > > > > On 2020-12-21 14:53, Vinod Koul wrote: > > > > > Hello, > > > > > > > > > > On 17-12-20, 20:07, Md Sadre Alam wrote: > > > > > > This change will add support for LOCK & UNLOCK flag bit support > > > > > > on CMD descriptor. > > > > > > > > > > > > If DMA_PREP_LOCK flag passed in prep_slave_sg then requester of this > > > > > > transaction wanted to lock the DMA controller for this transaction so > > > > > > BAM driver should set LOCK bit for the HW descriptor. > > > > > > > > > > > > If DMA_PREP_UNLOCK flag passed in prep_slave_sg then requester > > > > > > of this > > > > > > transaction wanted to unlock the DMA controller.so BAM driver > > > > > > should set > > > > > > UNLOCK bit for the HW descriptor. > > > > > > > > > > Can you explain why would we need to first lock and then unlock..? How > > > > > would this be used in real world. > > > > > > > > > > I have read a bit of documentation but is unclear to me. Also should > > > > > this be exposed as an API to users, sounds like internal to driver..? > > > > > > > > > > > > > IPQ5018 SoC having only one Crypto Hardware Engine. This Crypto Hardware > > > > Engine > > > > will be shared between A53 core & ubi32 core. There is two separate > > > > driver dedicated > > > > to A53 core and ubi32 core. So to use Crypto Hardware Engine > > > > parallelly for encryption/description > > > > we need bam locking mechanism. if one driver will submit the request > > > > for encryption/description > > > > to Crypto then first it has to set LOCK flag bit on command descriptor > > > > so that other pipes will > > > > get locked. > > > > > > > > The Pipe Locking/Unlocking will be only on command-descriptor. Upon > > > > encountering a command descriptor > > > > Can you explain what is a cmd descriptor? > > In BAM pipe descriptor structure there is a field called CMD (Command > descriptor). > CMD allows the SW to create descriptors of type Command which does not > generate any data transmissions > but configures registers in the Peripheral (write operations, and read > registers operations ). > Using command descriptor enables the SW to queue new configurations > between data transfers in advance. What and when is the CMD descriptor used for..? > > > > > > with LOCK bit set, The BAM will lock all other pipes not related to > > > > the current pipe group, and keep > > > > handling the current pipe only until it sees the UNLOCK set then it > > > > will release all locked pipes. > > > > locked pipe will not fetch new descriptors even if it got event/events > > > > adding more descriptors for > > > > this pipe (locked pipe). > > > > > > > > No need to expose as an API to user because its internal to driver, so > > > > while preparing command descriptor > > > > just we have to update the LOCK/UNLOCK flag. > > > > So IIUC, no api right? it would be internal to driver..? > > Yes its totally internal to deriver. So no need for this patch then, right? -- ~Vinod
