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

Sanjay R Mehta
2021-06-16T05:23:50Z

On 6/16/2021 9:48 AM, Vinod Koul wrote:
> [CAUTION: External Email]
>
> On 15-06-21, 17:04, Sanjay R Mehta wrote:
>>
>>
>> On 6/9/2021 12:26 AM, Vinod Koul wrote:
>>
>> [snipped]
>>
>>>> +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?
>>>
>>
>> Do you think this should be a major blocker for pulling this series in 5.14?
>> Would you be okay to accept this change in the subsequent driver updates?
>
> Sorry that is not how upstream works, I would like things to be better
> before we merge this
>

Sure Vinod, I will fix this and send the change in next version.

>>
>>>> +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?
>
> This and many more comments are left not replied, do you agree to them,
> do you disagree, hard to tell from silence..
>

Yes, I agree with all other comments and will send the changes in next
version of the patch series.

>>>
>>>> + 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 ...
>>
>> This DMA controller is intended to be used with AMD Non-Transparent
>> Bridge devices and not for general purpose peripheral DMA. Hence marking
>> it as DMA_PRIVATE.
>
> Okay, maybe add a comment so that people would know
>

Sure. I will add comment here.

> --
> ~Vinod
>