On 18-05-18, 10:04, Wen He wrote: > > > > > +u64 pre_addr, pre_queue; > > > > > > > > why do we have a global? > > > > > > Let's us see qDMA that how is works? > > > > > > First, the status notification for DMA jobs are reported back to the status > > queue. > > > Status information is carried within the command descriptor > > > status/command field, bits 120-127. The command descriptor dequeue > > > pointer advances only after the transaction has completed and the status > > information field has been updated. > > > > > > Then, the command descriptor address field wiil pointer to the command > > > descriptor in its original format. It is the responsibity of the > > > address of the status queue consumer to deallocate buffers as needed when > > the command descriptor address pointer is non-zero. > > > > > > More details of the Status Queue can be found in QorIQ Layerscape Soc > > datasheet. > > > > > > So, these variable is used to record latest value that command > > > descriptor queue and status field. > > > > > > Every time variables value is zero when set these variable to local, that's not > > what I want. > > > > Why not store them in driver context? > > > > okay, maybe I should remove these variable to private struct? Yes that would be better > > > > > + memset(sg_block->virt_addr, 0, > > > > > + FSL_QDMA_EXPECT_SG_ENTRY_NUM * 16); > > > > > > > > why FSL_QDMA_EXPECT_SG_ENTRY_NUM * 16? and not what you > > allocated? > > > > > > > > > > see line 497. > > > The sg_pool buffer size created is FSL_QDMA_EXPECT_SG_ENTRY_NUM * > > 16. > > > > Please document this > > > Add comment to this? yup, explaining where 16 is coming from -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
