Date:   Wed, 28 Jul 2021 14:46:46 +0530
From:   Sanjay R Mehta <sanmehta@....com>
To:     Vinod Koul <vkoul@...nel.org>, 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 v10 1/3] dmaengine: ptdma: Initial driver for the AMD
 PTDMA


On 7/28/2021 11:25 AM, Vinod Koul wrote:
> [CAUTION: External Email]
> 

Thanks Vinod for the feedback.

> On 20-06-21, 11:41, Sanjay R Mehta wrote:
> 
>> +static irqreturn_t pt_core_irq_handler(int irq, void *data)
>> +{
>> +     struct pt_device *pt = data;
>> +     struct pt_cmd_queue *cmd_q = &pt->cmd_q;
>> +     u32 status;
>> +     bool err = true;
>> +
>> +     pt_core_disable_queue_interrupts(pt);
>> +
>> +     status = ioread32(cmd_q->reg_interrupt_status);
>> +     if (status) {
>> +             cmd_q->int_status = status;
>> +             cmd_q->q_status = ioread32(cmd_q->reg_status);
>> +             cmd_q->q_int_status = ioread32(cmd_q->reg_int_status);
>> +
>> +             /* On error, only save the first error value */
>> +             if ((status & INT_ERROR) && !cmd_q->cmd_error) {
>> +                     cmd_q->cmd_error = CMD_Q_ERROR(cmd_q->q_status);
>> +                     err = false;
>> +             }
>> +
>> +             /* Acknowledge the interrupt */
>> +             iowrite32(status, cmd_q->reg_interrupt_status);
>> +     }
>> +
>> +     pt_core_enable_queue_interrupts(pt);
>> +
>> +     return err ? IRQ_HANDLED : IRQ_NONE;
> 
> On err you should not return IRQ_NONE. IRQ_NONE means "interrupt was not
> from this device or was not handled"
> 
> Error is handled here!
> 
Got  it. Sure, will change it.

>> +static struct pt_device *pt_alloc_struct(struct device *dev)
>> +{
>> +     struct pt_device *pt;
>> +
>> +     pt = devm_kzalloc(dev, sizeof(*pt), GFP_KERNEL);
>> +
>> +     if (!pt)
>> +             return NULL;
>> +     pt->dev = dev;
>> +
>> +     INIT_LIST_HEAD(&pt->cmd);
>> +
>> +     snprintf(pt->name, MAX_PT_NAME_LEN, "pt-%s", dev_name(dev));
> 
> what is this name used for? Why not use dev_name everywhere?
> 
Sure, will change it to  dev_name.

>> +static int pt_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>> +{
>> +     struct pt_device *pt;
>> +     struct pt_msix *pt_msix;
>> +     struct device *dev = &pdev->dev;
>> +     void __iomem * const *iomap_table;
>> +     int bar_mask;
>> +     int ret = -ENOMEM;
>> +
>> +     pt = pt_alloc_struct(dev);
>> +     if (!pt)
>> +             goto e_err;
>> +
>> +     pt_msix = devm_kzalloc(dev, sizeof(*pt_msix), GFP_KERNEL);
>> +     if (!pt_msix)
>> +             goto e_err;
>> +
>> +     pt->pt_msix = pt_msix;
>> +     pt->dev_vdata = (struct pt_dev_vdata *)id->driver_data;
>> +     if (!pt->dev_vdata) {
>> +             ret = -ENODEV;
>> +             dev_err(dev, "missing driver data\n");
>> +             goto e_err;
>> +     }
>> +
>> +     ret = pcim_enable_device(pdev);
>> +     if (ret) {
>> +             dev_err(dev, "pcim_enable_device failed (%d)\n", ret);
>> +             goto e_err;
>> +     }
>> +
>> +     bar_mask = pci_select_bars(pdev, IORESOURCE_MEM);
>> +     ret = pcim_iomap_regions(pdev, bar_mask, "ptdma");
>> +     if (ret) {
>> +             dev_err(dev, "pcim_iomap_regions failed (%d)\n", ret);
>> +             goto e_err;
>> +     }
>> +
>> +     iomap_table = pcim_iomap_table(pdev);
>> +     if (!iomap_table) {
>> +             dev_err(dev, "pcim_iomap_table failed\n");
>> +             ret = -ENOMEM;
>> +             goto e_err;
>> +     }
>> +
>> +     pt->io_regs = iomap_table[pt->dev_vdata->bar];
>> +     if (!pt->io_regs) {
>> +             dev_err(dev, "ioremap failed\n");
>> +             ret = -ENOMEM;
>> +             goto e_err;
>> +     }
>> +
>> +     ret = pt_get_irqs(pt);
>> +     if (ret)
>> +             goto e_err;
>> +
>> +     pci_set_master(pdev);
>> +
>> +     ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(48));
>> +     if (ret) {
>> +             ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
>> +             if (ret) {
>> +                     dev_err(dev, "dma_set_mask_and_coherent failed (%d)\n",
>> +                             ret);
>> +                     goto e_err;
>> +             }
>> +     }
>> +
>> +     dev_set_drvdata(dev, pt);
>> +
>> +     if (pt->dev_vdata)
>> +             ret = pt_core_init(pt);
>> +
>> +     if (ret)
>> +             goto e_err;
>> +
>> +     return 0;
>> +
>> +e_err:
>> +     dev_err(dev, "initialization failed\n");
> 
> log the err code, that is very useful!
> 
>> +     /* Register addresses for queue */
>> +     void __iomem *reg_control;
>> +     void __iomem *reg_tail_lo;
>> +     void __iomem *reg_head_lo;
>> +     void __iomem *reg_int_enable;
>> +     void __iomem *reg_interrupt_status;
>> +     void __iomem *reg_status;
>> +     void __iomem *reg_int_status;
>> +     void __iomem *reg_dma_status;
>> +     void __iomem *reg_dma_read_status;
>> +     void __iomem *reg_dma_write_status;
> 
> this looks like pointer to registers, wont it make sense to keep base
> ptr and use offset to read..?
> 
> Looking at pt_init_cmdq_regs(), i think that seems to be the case. Why
> waste so much memory by having so many pointers?
> 
Yes, you are right. I will make this changes.

> 
>> +     u32 qcontrol; /* Cached control register */
>> +
>> +     /* Status values from job */
>> +     u32 int_status;
>> +     u32 q_status;
>> +     u32 q_int_status;
>> +     u32 cmd_error;
>> +} ____cacheline_aligned;
>> +
>> +struct pt_device {
>> +     struct list_head entry;
>> +
>> +     unsigned int ord;
> 
> Unused?
> 

Sure. Will remove it.
> --
> ~Vinod
> 

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