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Date: Fri, 15 May 2009 10:54:16 +0200
From: Wolfgang Grandegger <wg@...ndegger.com>
To: Jonathan Corbet <corbet@....net>
CC: netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
Per Dalen <per.dalen@....se>
Subject: Re: [PATCH v2 7/7] [PATCH 7/8] can: SJA1000 driver for Kvaser PCI
cards
Jonathan Corbet wrote:
> On Tue, 12 May 2009 11:28:04 +0200
> Wolfgang Grandegger <wg@...ndegger.com> wrote:
>
>> The patch adds support for the PCI cards: PCIcan and PCIcanx
>> (1, 2 or 4 channel) from Kvaser (http://www.kvaser.com).
>
>> +static void kvaser_pci_disable_irq(struct net_device *dev)
>> +{
>> + struct sja1000_priv *priv = netdev_priv(dev);
>> + struct kvaser_pci *board = priv->priv;
>> + u32 tmp;
>
> I've seen certain reviewers getting grumpy about variables called "tmp"
> recently.
No problem. I'm going to change the name to something more reasonable.
>> + /* Disable interrupts from card */
>> + tmp = ioread32(board->conf_addr + S5920_INTCSR);
>> + tmp &= ~INTCSR_ADDON_INTENABLE_M;
>> + iowrite32(tmp, board->conf_addr + S5920_INTCSR);
>> +}
>
> [...]
>
>> +static int number_of_sja1000_chip(void __iomem *base_addr)
>> +{
>> + u8 status;
>> + int i;
>> +
>> + for (i = 0; i < MAX_NO_OF_CHANNELS; i++) {
>> + /* reset chip */
>> + iowrite8(MOD_RM, base_addr +
>> + (i * KVASER_PCI_PORT_BYTES) + REG_MOD);
>> + status = ioread8(base_addr +
>> + (i * KVASER_PCI_PORT_BYTES) + REG_MOD);
>> + udelay(10);
>> + /* check reset bit */
>> + if (!(status & MOD_RM))
>> + break;
>
> Why would you delay before checking status? It ain't gonna change.
Right.
>> + }
>> +
>> + return i;
>> +}
>> +
>> +static void kvaser_pci_del_chan(struct net_device *dev)
>> +{
>> + struct sja1000_priv *priv;
>> + struct kvaser_pci *board;
>> + int i;
>> +
>> + if (!dev)
>> + return;
>> + priv = netdev_priv(dev);
>> + if (!priv)
>> + return;
>
> Can this happen?
No, it's a bug if it happens.
>> + board = priv->priv;
>> + if (!board)
>> + return;
>> +
>> + dev_info(&board->pci_dev->dev, "Removing device %s\n",
>> + dev->name);
>> +
>> + for (i = 0; i < board->no_channels - 1; i++) {
>> + if (board->slave_dev[i]) {
>> + dev_info(&board->pci_dev->dev, "Removing device %s\n",
>> + board->slave_dev[i]->name);
>> + unregister_sja1000dev(board->slave_dev[i]);
>> + free_sja1000dev(board->slave_dev[i]);
>> + }
>> + }
>> + unregister_sja1000dev(dev);
>> +
>> + /* Disable PCI interrupts */
>> + kvaser_pci_disable_irq(dev);
>
> It seems to me like you might want to disable interrupts *before* tearing
> down all that structure? What happens if it interrupts after the sja1000
> layer has forgotten about it?
Right.
>> + pci_iounmap(board->pci_dev, (void __iomem *)dev->base_addr);
>> + pci_iounmap(board->pci_dev, board->conf_addr);
>> + pci_iounmap(board->pci_dev, board->res_addr);
>> +
>> + free_sja1000dev(dev);
>> +}
>> +
>> +static int kvaser_pci_add_chan(struct pci_dev *pdev, int channel,
>> + struct net_device **master_dev,
>> + void __iomem *conf_addr,
>> + void __iomem *res_addr,
>> + unsigned long base_addr)
>> +{
>> + struct net_device *dev;
>> + struct sja1000_priv *priv;
>> + struct kvaser_pci *board;
>> + int err, init_step;
>> +
>> + dev = alloc_sja1000dev(sizeof(struct kvaser_pci));
>> + if (dev == NULL)
>> + return -ENOMEM;
>> +
>> + priv = netdev_priv(dev);
>
> Here you don't have the !priv check.
>
>> + board = priv->priv;
>> +
>> + board->pci_dev = pdev;
>> + board->channel = channel;
>> +
>> + /*S5920*/
>> + board->conf_addr = conf_addr;
>> +
>> + /*XILINX board wide address*/
>> + board->res_addr = res_addr;
>> +
>> + if (channel == 0) {
>> + board->xilinx_ver =
>> + ioread8(board->res_addr + XILINX_VERINT) >> 4;
>> + init_step = 2;
>> +
>> + /* Assert PTADR# - we're in passive mode so the other bits are
>> + not important */
>> + iowrite32(0x80808080UL, board->conf_addr + S5920_PTCR);
>> +
>> + /* Disable interrupts from card */
>> + kvaser_pci_disable_irq(dev);
>> + /* Enable interrupts from card */
>> + kvaser_pci_enable_irq(dev);
>
> I'm sure there's a perfectly good reason for the disable/enable dance.
> Presumably the hardware needs it or it misbehaves? Worth commenting.
Hm, I think the hardware does not need it. I will check with original other.
>> + } else {
>> + struct sja1000_priv *master_priv = netdev_priv(*master_dev);
>> + struct kvaser_pci *master_board = master_priv->priv;
>> + master_board->slave_dev[channel - 1] = dev;
>> + master_board->no_channels = channel + 1;
>> + board->xilinx_ver = master_board->xilinx_ver;
>> + }
>> +
>> + dev->base_addr = base_addr + channel * KVASER_PCI_PORT_BYTES;
>> +
>> + priv->read_reg = kvaser_pci_read_reg;
>> + priv->write_reg = kvaser_pci_write_reg;
>> +
>> + priv->can.clock.freq = KVASER_PCI_CAN_CLOCK;
>> +
>> + priv->ocr = KVASER_PCI_OCR;
>> + priv->cdr = KVASER_PCI_CDR;
>> +
>> + /* Register and setup interrupt handling */
>> + dev->irq = pdev->irq;
>> + init_step = 4;
>> +
>> + dev_info(&pdev->dev, "base_addr=%#lx conf_addr=%p irq=%d\n",
>> + dev->base_addr, board->conf_addr, dev->irq);
>> +
>> + SET_NETDEV_DEV(dev, &pdev->dev);
>> +
>> + /* Register SJA1000 device */
>> + err = register_sja1000dev(dev);
>> + if (err) {
>> + dev_err(&pdev->dev, "Registering device failed (err=%d)\n",
>> + err);
>> + goto failure;
>> + }
>> +
>> + if (channel == 0)
>> + *master_dev = dev;
>> +
>> + return 0;
>> +
>> +failure:
>> + kvaser_pci_del_chan(dev);
>> + return err;
>> +}
>> +
>> +static int __devinit kvaser_pci_init_one(struct pci_dev *pdev,
>> + const struct pci_device_id *ent)
>> +{
>> + int err;
>> + struct net_device *master_dev = NULL;
>> + struct sja1000_priv *priv;
>> + struct kvaser_pci *board;
>> + int no_channels;
>> + void __iomem *base_addr = NULL;
>> + void __iomem *conf_addr = NULL;
>> + void __iomem *res_addr = NULL;
>> + int i;
>> +
>> + dev_info(&pdev->dev, "initializing device %04x:%04x\n",
>> + pdev->vendor, pdev->device);
>> +
>> + err = pci_enable_device(pdev);
>> + if (err)
>> + goto failure;
>> +
>> + err = pci_request_regions(pdev, DRV_NAME);
>> + if (err)
>> + goto failure_release_pci;
>> +
>> + /*S5920*/
>> + conf_addr = pci_iomap(pdev, 0, PCI_CONFIG_PORT_SIZE);
>> + if (conf_addr == NULL) {
>> + err = -ENODEV;
>> + goto failure_iounmap;
>
> Why go there? You know there's nothing to unmap.
OK.
I will resend a revised patch a.s.a.p.
Thanks,
Wolfgang.
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