linux-kernel - Re: [RFC 4/6] dmaengine: xilinx_dma: Freeup active list based on descriptor completion bit

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Message-ID: <20180411091102.GZ6014@localhost>
Date:   Wed, 11 Apr 2018 14:41:03 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Radhey Shyam Pandey <radhey.shyam.pandey@...inx.com>
Cc:     dan.j.williams@...el.com, michal.simek@...inx.com,
        appana.durga.rao@...inx.com, radheys@...inx.com, lars@...afoo.de,
        dmaengine@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC 4/6] dmaengine: xilinx_dma: Freeup active list based on
 descriptor completion bit

On Mon, Apr 02, 2018 at 04:09:04PM +0530, Radhey Shyam Pandey wrote:
> AXIDMA IP sets completion bit to 1 when the transfer is completed. Read
> this bit to move descriptor from active list to the done list. This feature
> is needed when interrupt delay timeout and IRQThreshold is enabled i.e
> Dly_IrqEn is triggered w/o completing Interrupt Threshold.
> 
> Signed-off-by: Radhey Shyam Pandey <radheys@...inx.com>
> ---
>  drivers/dma/xilinx/xilinx_dma.c |   18 ++++++++++++++----
>  1 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
> index 36e1ab9..518465e 100644
> --- a/drivers/dma/xilinx/xilinx_dma.c
> +++ b/drivers/dma/xilinx/xilinx_dma.c
> @@ -103,6 +103,7 @@
>  #define XILINX_DMA_PARK_PTR_RD_REF_SHIFT	0
>  #define XILINX_DMA_PARK_PTR_RD_REF_MASK		GENMASK(4, 0)
>  #define XILINX_DMA_REG_VDMA_VERSION		0x002c
> +#define XILINX_DMA_COMP_MASK			BIT(31)
>  
>  /* Register Direct Mode Registers */
>  #define XILINX_DMA_REG_VSIZE			0x0000
> @@ -1387,16 +1388,25 @@ static void xilinx_dma_issue_pending(struct dma_chan *dchan)
>  static void xilinx_dma_complete_descriptor(struct xilinx_dma_chan *chan)
>  {
>  	struct xilinx_dma_tx_descriptor *desc, *next;
> +	struct xilinx_axidma_tx_segment *seg;
>  
>  	/* This function was invoked with lock held */
>  	if (list_empty(&chan->active_list))
>  		return;
>  
>  	list_for_each_entry_safe(desc, next, &chan->active_list, node) {
> -		list_del(&desc->node);
> -		if (!desc->cyclic)
> -			dma_cookie_complete(&desc->async_tx);
> -		list_add_tail(&desc->node, &chan->done_list);
> +
> +		seg = list_last_entry(&desc->segments,
> +				      struct xilinx_axidma_tx_segment, node);
> +		if ((seg->hw.status & XILINX_DMA_COMP_MASK) ||
> +			(!chan->xdev->has_axieth_connected)) {

why the second case ? That is not expalined in log?

> +			list_del(&desc->node);
> +			if (!desc->cyclic)
> +				dma_cookie_complete(&desc->async_tx);
> +			list_add_tail(&desc->node, &chan->done_list);
> +		} else {
> +			break;
> +		}
>  	}
>  }
>  
> -- 
> 1.7.1
> 

-- 
~Vinod