linux-kernel - Re: [PATCH v6 2/4] dmaengine: mediatek-cqdma: remove redundant queue structure

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Date:   Wed, 15 Jul 2020 11:49:57 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     EastL Lee <EastL.Lee@...iatek.com>
Cc:     Sean Wang <sean.wang@...iatek.com>, robh+dt@...nel.org,
        mark.rutland@....com, matthias.bgg@...il.com,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, devicetree@...r.kernel.org,
        wsd_upstream@...iatek.com, cc.hwang@...iatek.com
Subject: Re: [PATCH v6 2/4] dmaengine: mediatek-cqdma: remove redundant queue
 structure

On 02-07-20, 15:06, EastL Lee wrote:

>  static enum dma_status mtk_cqdma_tx_status(struct dma_chan *c,
>  					   dma_cookie_t cookie,
>  					   struct dma_tx_state *txstate)
>  {
> -	struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
> -	struct mtk_cqdma_vdesc *cvd;
> -	struct virt_dma_desc *vd;
> -	enum dma_status ret;
> -	unsigned long flags;
> -	size_t bytes = 0;
> -
> -	ret = dma_cookie_status(c, cookie, txstate);
> -	if (ret == DMA_COMPLETE || !txstate)
> -		return ret;
> -
> -	spin_lock_irqsave(&cvc->vc.lock, flags);
> -	vd = mtk_cqdma_find_active_desc(c, cookie);
> -	spin_unlock_irqrestore(&cvc->vc.lock, flags);
> -
> -	if (vd) {
> -		cvd = to_cqdma_vdesc(vd);
> -		bytes = cvd->residue;
> -	}
> -
> -	dma_set_residue(txstate, bytes);

any reason why you want to remove setting residue?

> -static void mtk_cqdma_free_active_desc(struct dma_chan *c)
> +static int mtk_cqdma_terminate_all(struct dma_chan *c)
>  {
>  	struct mtk_cqdma_vchan *cvc = to_cqdma_vchan(c);
> -	bool sync_needed = false;
> +	struct virt_dma_chan *vc = to_virt_chan(c);
>  	unsigned long pc_flags;
>  	unsigned long vc_flags;
> +	LIST_HEAD(head);
> +
> +	/* wait for the VC to be inactive  */
> +	if (!wait_for_completion_timeout(&cvc->cmp, msecs_to_jiffies(3000)))
> +		return -EAGAIN;
>  
>  	/* acquire PC's lock first due to lock dependency in dma ISR */
>  	spin_lock_irqsave(&cvc->pc->lock, pc_flags);
>  	spin_lock_irqsave(&cvc->vc.lock, vc_flags);
>  
> -	/* synchronization is required if this VC is active */
> -	if (mtk_cqdma_is_vchan_active(cvc)) {
> -		cvc->issue_synchronize = true;
> -		sync_needed = true;
> -	}
> +	/* get VDs from lists */
> +	vchan_get_all_descriptors(vc, &head);
> +
> +	/* free all the VDs */
> +	vchan_dma_desc_free_list(vc, &head);
>  
>  	spin_unlock_irqrestore(&cvc->vc.lock, vc_flags);
>  	spin_unlock_irqrestore(&cvc->pc->lock, pc_flags);

Good cleanup, do you need both these locks?
-- 
~Vinod