linux-kernel - Re: [PATCH v9 2/3] dmaengine: ptdma: register PTDMA controller as a DMA resource

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Message-ID: <YL+9Y8U8XQ2FSV8Q@vkoul-mobl>
Date:   Wed, 9 Jun 2021 00:26:35 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Sanjay R Mehta <Sanju.Mehta@....com>
Cc:     gregkh@...uxfoundation.org, dan.j.williams@...el.com,
        Thomas.Lendacky@....com, Shyam-sundar.S-k@....com,
        Nehal-bakulchandra.Shah@....com, robh@...nel.org,
        mchehab+samsung@...nel.org, davem@...emloft.net,
        linux-kernel@...r.kernel.org, dmaengine@...r.kernel.org
Subject: Re: [PATCH v9 2/3] dmaengine: ptdma: register PTDMA controller as a
 DMA resource

On 02-06-21, 12:22, Sanjay R Mehta wrote:

> +static void pt_do_cmd_complete(unsigned long data)
> +{
> +	struct pt_tasklet_data *tdata = (struct pt_tasklet_data *)data;
> +	struct pt_cmd *cmd = tdata->cmd;
> +	struct pt_cmd_queue *cmd_q = &cmd->pt->cmd_q;
> +	u32 tail;
> +
> +	tail = lower_32_bits(cmd_q->qdma_tail + cmd_q->qidx * Q_DESC_SIZE);

why extract tail in non error case?

> +static int pt_issue_next_cmd(struct pt_dma_desc *desc)
> +{
> +	struct pt_passthru_engine *pt_engine;
> +	struct pt_dma_cmd *cmd;
> +	struct pt_device *pt;
> +	struct pt_cmd *pt_cmd;
> +	struct pt_cmd_queue *cmd_q;
> +
> +	cmd = list_first_entry(&desc->cmdlist, struct pt_dma_cmd, entry);
> +	desc->issued_to_hw = 1;

Why do you need this, the descriptor should be in vc.desc_issued list

> +static void pt_free_active_cmd(struct pt_dma_desc *desc)
> +{
> +	struct pt_dma_cmd *cmd = NULL;
> +
> +	if (desc->issued_to_hw)
> +		cmd = list_first_entry_or_null(&desc->cmdlist, struct pt_dma_cmd,
> +					       entry);

single line pls and use lists provided..


> +static struct pt_dma_desc *pt_handle_active_desc(struct pt_dma_chan *chan,
> +						 struct pt_dma_desc *desc)
> +{
> +	struct dma_async_tx_descriptor *tx_desc;
> +	struct virt_dma_desc *vd;
> +	unsigned long flags;
> +
> +	/* Loop over descriptors until one is found with commands */
> +	do {
> +		if (desc) {
> +			/* Remove the DMA command from the list and free it */
> +			pt_free_active_cmd(desc);
> +			if (!desc->issued_to_hw) {
> +				/* No errors, keep going */
> +				if (desc->status != DMA_ERROR)
> +					return desc;
> +				/* Error, free remaining commands and move on */
> +				pt_free_cmd_resources(desc->pt,
> +						      &desc->cmdlist);

single line again

> +static struct pt_dma_desc *pt_alloc_dma_desc(struct pt_dma_chan *chan,
> +					     unsigned long flags)
> +{
> +	struct pt_dma_desc *desc;
> +
> +	desc = kmem_cache_zalloc(chan->pt->dma_desc_cache, GFP_NOWAIT);
> +	if (!desc)
> +		return NULL;
> +
> +	vchan_tx_prep(&chan->vc, &desc->vd, flags);
> +
> +	desc->pt = chan->pt;
> +	desc->issued_to_hw = 0;
> +	INIT_LIST_HEAD(&desc->cmdlist);

why do you need your own list, the lists in vc should suffice?

> +static int pt_resume(struct dma_chan *dma_chan)
> +{
> +	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
> +	struct pt_dma_desc *desc = NULL;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&chan->vc.lock, flags);
> +	pt_start_queue(&chan->pt->cmd_q);
> +	desc = __pt_next_dma_desc(chan);
> +	spin_unlock_irqrestore(&chan->vc.lock, flags);
> +
> +	/* If there was something active, re-start */
> +	if (desc)
> +		pt_cmd_callback(desc, 0);

this doesn't sound correct. In pause yoy stop the queue, so start of the
queue should be done here... Why grab a descriptor?

> +static int pt_terminate_all(struct dma_chan *dma_chan)
> +{
> +	struct pt_dma_chan *chan = to_pt_chan(dma_chan);
> +
> +	vchan_free_chan_resources(&chan->vc);

what about the descriptors, are you not going to clear the lists and
free them..

> +int pt_dmaengine_register(struct pt_device *pt)
> +{
> +	struct pt_dma_chan *chan;
> +	struct dma_device *dma_dev = &pt->dma_dev;
> +	char *cmd_cache_name;
> +	char *desc_cache_name;
> +	int ret;
> +
> +	pt->pt_dma_chan = devm_kzalloc(pt->dev, sizeof(*pt->pt_dma_chan),
> +				       GFP_KERNEL);
> +	if (!pt->pt_dma_chan)
> +		return -ENOMEM;
> +
> +	cmd_cache_name = devm_kasprintf(pt->dev, GFP_KERNEL,
> +					"%s-dmaengine-cmd-cache",
> +					pt->name);
> +	if (!cmd_cache_name)
> +		return -ENOMEM;
> +
> +	pt->dma_cmd_cache = kmem_cache_create(cmd_cache_name,
> +					      sizeof(struct pt_dma_cmd),
> +					      sizeof(void *),
> +					      SLAB_HWCACHE_ALIGN, NULL);
> +	if (!pt->dma_cmd_cache)
> +		return -ENOMEM;
> +
> +	desc_cache_name = devm_kasprintf(pt->dev, GFP_KERNEL,
> +					 "%s-dmaengine-desc-cache",
> +					 pt->name);
> +	if (!desc_cache_name) {
> +		ret = -ENOMEM;
> +		goto err_cache;
> +	}
> +
> +	pt->dma_desc_cache = kmem_cache_create(desc_cache_name,
> +					       sizeof(struct pt_dma_desc),
> +					       sizeof(void *),

sizeof void ptr?

> +					       SLAB_HWCACHE_ALIGN, NULL);
> +	if (!pt->dma_desc_cache) {
> +		ret = -ENOMEM;
> +		goto err_cache;
> +	}
> +
> +	dma_dev->dev = pt->dev;
> +	dma_dev->src_addr_widths = DMA_SLAVE_BUSWIDTH_64_BYTES;
> +	dma_dev->dst_addr_widths = DMA_SLAVE_BUSWIDTH_64_BYTES;
> +	dma_dev->directions = DMA_MEM_TO_MEM;
> +	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
> +	dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
> +	dma_cap_set(DMA_INTERRUPT, dma_dev->cap_mask);
> +	dma_cap_set(DMA_PRIVATE, dma_dev->cap_mask);

Why DMA_PRIVATE ? this is a dma mempcy controller ...
-- 
~Vinod