Messages in this thread | | | Date | Tue, 22 Dec 2020 17:48:31 +0530 | From | mdalam@codeauro ... | Subject | Re: [PATCH] dmaengine: qcom: bam_dma: Add LOCK and UNLOCK flag bit support |
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On 2020-12-21 23:39, Thara Gopinath wrote: > On 12/21/20 2:35 AM, mdalam@codeaurora.org wrote: >> On 2020-12-19 09:05, Thara Gopinath wrote: >>> On 12/17/20 9:37 AM, 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. >>> Hi, >>> >>> This is a generic question. What is the point of LOCK/UNLOCK with >>> allocating LOCK groups to the individual dma channels? By default >>> doesn't all channels fall in the same group. This would mean that >>> a lock does not prevent the dma controller from not executing a >>> transaction on the other channels. >>> >> >> The Pipe Locking/Unlocking will be only on command-descriptor. >> Upon encountering a command descriptor 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. > > So unless you assign pipe groups, this will not work as intended > right? So this patch is only half of the solution. There should also > be a patch allowing pipe groups to be assigned. Without that extra bit > this patch does nothing , right ?
Yes you are right. We are having some register which will configure the pipe lock group. But these registers are not exposed to non-secure world. These registers only accessible through secure world. Currently in IPQ5018 SoC we are configuring these register in secure world to configure pipe lock group.
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