[PATCH 1/3] dmaengine: xilinx_dma: Check for channel idle state before submitting dma descriptor
From: appana.durga.rao@xilinx.com (Appana Durga Kedareswara Rao)
Date: 2016-12-19 15:54:05
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Hi Laurent Pinchart, Thanks for the review...
quoted
+ if (!chan->idle) + return;Don't you need to perform the same check for the DMA and CDMA channels ? If so, shouldn't this be moved to common code ?
Will fix it in v2...
There's another problem (not strictly introduced by this patch) I wanted to mention. The append_desc_queue() function, called from your tx_submit handler, appends descriptors to the pending_list. The DMA engine API states that a transfer submitted by tx_submit will not be executed until .issue_pending() is called. However, if a transfer is in progress at tx_submit time, I believe that the IRQ handler, at transfer completion, will start the next transfer from the pending_list even if .issue_pending() hasn't been called for it.quoted
if (list_empty(&chan->pending_list)) return;
If user submits more than h/w limit then that case only driver will process The descriptors from the pending_list for other cases the pending_list will be Empty so driver just returns from there.
Now that you catch busy channels with a software flag, do you still need the xilinx_dma_is_running() and xilinx_dma_is_idle() checks ? Three different checks for the same or very similar conditions are confusing, if you really need them you should document clearly how they differ.
Will remove the xilinx_dma_is_running and xilinx_dmais_idle() checks and will use Chan->idle check across all the IP's. Will fix it v2...
quoted
@@ -1110,6 +1116,7 @@ static void xilinx_vdma_start_transfer(structxilinx_dma_chan *chan) vdma_desc_write(chan, XILINX_DMA_REG_VSIZE, last->hw.vsize); } + chan->idle = false;(and this too)
Will fix in v2... Regards, Kedar.