Re: PATCH: PMC-Sierra MaxRAID driver to support 6Gb/s SAS RAID controller

Anil Ravindranath
2009-06-13T09:32:05Z

Please see my responses below...

On Thu, 11 Jun 2009, Rolf Eike Beer wrote:

> Anil Ravindranath wrote:
> > Hi,
> >
> > This patch adds a driver to support PMC-Sierra 6Gb/s SAS RAID controller.
> > This patch is created against scsi-misc-2.6.git.
>
> > +module_param_named(debug, pmcraid_debug, uint, (S_IRUGO | S_IWUSR));
> > +MODULE_PARM_DESC(debug,
> > + "Enable driver verbose message logging. Set 1 to enable."
> > + "(default: 0)");
>
> I would say that "1" would enable this is rather obvious. And since this is
> only 0 or 1 better use bool instead of uint.
>
This can be changed to bool as well. But in future if we want to add more
than two values, hence we kept int for now.

>
> > +static int pmcraid_slave_alloc(struct scsi_device *scsi_dev)
> > +{
> > + struct pmcraid_resource_entry *temp, *res = NULL;
> > + struct pmcraid_instance *pinstance;
> > + u8 target, bus, lun;
> > + unsigned long lock_flags;
> > + int rc = -ENXIO;
> > +
> > + pinstance = (struct pmcraid_instance *)scsi_dev->host->hostdata;
>
> hostdata is void* AFAIR so there is no need to cast. It's C, there is no need
> to cast to or from void* anywhere if the other thing is a pointer.
>

Will use shost_priv() here.

> > +static int pmcraid_slave_configure(struct scsi_device *sdev)
> > +{
> > + struct pmcraid_resource_entry *res = NULL;
> > +
> > + res = sdev->hostdata;
>
> No need to initialize res to NULL.
>
Agreed. Remove initalize to NULL here.

> > +static u32 pmcraid_read_interrupts(struct pmcraid_instance *pinstance)
> > +{
> > +
> > + return ioread32(pinstance->int_regs.ioa_host_interrupt_reg);
> > +}
>
> Extra newline.
>

Will remove extra newline

> > +/**
> > + * pmcraid_disable_interrupts - Masks and clears all specified interrupts
> > + *
> > + * @pinstance: pointer to per adapter instance structure
> > + * @intr: interrupts to disable
> > + *
> > + * Return Value
> > + * None
> > + */
>
> Well, that's rather obvious if it's a void function, isn't it? ;)
>

Followed commenting convention. Can remove return value. no problem.

>
> > +static int __devinit pmcraid_probe(
> > + struct pci_dev *pdev,
> > + const struct pci_device_id *dev_id
> > +)
> > +{
> > + struct pmcraid_instance *pinstance;
> > + struct Scsi_Host *host;
> > + void __iomem *mapped_pci_addr;
> > + int rc = PCIBIOS_SUCCESSFUL;
> > +
> > + if (pmcraid_adapter_count >= PMCRAID_MAX_ADAPTERS) {
> > + pmcraid_err
> > + ("maximum number(%d) of supported adapters reached\n",
> > + pmcraid_adapter_count);
> > + return -ENOMEM;
> > + }
> > +
> > + pmcraid_adapter_count++;
>
> This counter may need a lock, else you might get into trouble.
>

I am not sure if we need lock here as we will hit probe serially for every
controller found.
That said, we will change it to atomic.

> > + rc = pci_enable_device(pdev);
>
> Well, I ask it every time, but nevertheless: why not use devres for your
> driver? It will make error handling in _probe as well as the _release stuff
> much easier.
>

If we choose devres approach, we will have to make make changes
accordingly. For now can we stick to pci functions.

> > + if (rc) {
> > + dev_err(&pdev->dev, "Cannot enable adapter\n");
> > + pmcraid_adapter_count--;
> > + goto out;
> > + }
>
> Just "return rc" here. This goto into the middle of the function just for a
> return is IMHO hard to read.
>

Will be done.

> > + dev_info(&pdev->dev,
> > + "Found IOA(%x:%x) on PCI bus %d slot %d with IRQ: %d\n",
> > + pdev->vendor, pdev->device, pdev->bus->number,
> > + PCI_SLOT(pdev->bus->number), pdev->irq);
>

Removed extra pci printing info.

> The IRQ and stuff is printed by request_irq() or such anyway. If you have
> enabled MSI the IRQ is a different one anyway.
>
> > + /* zero out entire instance structure */
> > + pinstance = (struct pmcraid_instance *)host->hostdata;
> > + memset(pinstance, 0, sizeof(struct pmcraid_instance));
>
> memset(pinstance, 0, sizeof(*pinstance));
>

Done.

> > + /* Schedule worker thread to handle CCN and take care of adding and
> > + * removing devices to OS
> > + */
> > + schedule_work(&pinstance->worker_q);
> > +
> > +out:
> > + return rc;
> > +
> > +out_remove_host:
> > + scsi_remove_host(host);
> > +
> > +out_release_bufs:
> > + pmcraid_release_buffers(pinstance);
> > +
> > +out_unregister_isr:
> > + pmcraid_kill_tasklets(pinstance);
> > + pmcraid_unregister_interrupt_handler(pinstance);
> > +
> > +out_scsi_host_put:
> > + scsi_host_put(host);
> > +
> > +cleanup_nomem:
> > + iounmap(mapped_pci_addr);
> > +
> > +out_release_regions:
> > + pci_release_regions(pdev);
> > +
> > +out_disable_device:
> > + pmcraid_adapter_count--;
> > + pci_set_drvdata(pdev, NULL);
> > + pci_disable_device(pdev);
> > + rc = -ENODEV;
> > + goto out;
> > +}
>
> Just "return rc" here. And maybe it's a good idea to just keep the previous rc
> so you will see it was ENOMEM or whatever.
>
Will remove goto out and add return -ENODEV if probe fails.

> > +/* PMC PCI vendor ID and device ID values */
> > +#define PCI_VENDOR_ID_PMC 0x11F8
> > +#define PCI_DEVICE_ID_PMC_MAXRAID 0x5220
> > +#define PCI_DEVICE_ID_PMC_0x8010 0x8010
>
> You could just use the 0x8010 directly at the only place this constant is
> referenced.
>

This will be changed once we add device_ids in pci_ids.h

> > +#define IOARCB_LENGTH_CODE(n) (((n)-3)/8 + (((n)-3)%8 > 0))
>
> Oh, wow. I needed to throw this into a for loop to understand what you are
> doing here. Try DIV_ROUND_CLOSEST(n, 8) from include/kernel.h which does right
> the same.
>

Done.

> > +/* macros to help in debugging */
> > +#define pmcraid_err(...) \
> > + printk(KERN_ERR "MaxRAID: "__VA_ARGS__)
> > +
> > +#define pmcraid_info(...) \
> > + if (pmcraid_debug) \
> > + printk(KERN_INFO "MaxRAID: "__VA_ARGS__)
>
> Those should probably be rewritten to use pr_err() and pr_debug(). Or better
> use dev_dbg() and dev_info() directly.
>
I guess we cannot use dev_ functions as we want to print even when dev is
not initialized. Yes we can use pr_ functions but we want to control
printing by our print/debug flags.

> > +/*
> > + * pmcraid_adapter_id - structure defining the adapter id used by LLD
> > + */
> > +union pmcraid_adapter_id {
> > + struct {
> > + u32 slot_no:8;
>
> Why not use u8?
>

PMC-sierra managament applications expect this to be an integer.

> > + u32 bus_number:24;
> > + } y;
>
> Greetings,
>
> Eike
>