[+cc linux-pci]
Hi Luis,
On Wed, Apr 29, 2015 at 02:36:09PM -0700, Luis R. Rodriguez wrote:
> From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
>
> Now that we have pci_iomap_wc() add the respective devres helpers.
I guess I'm still confused about the relationship between pci_iomap_wc()
and arch_phys_wc_add().
Do you expect every caller of pcim_iomap_wc() to also call
arch_phys_wc_add()?
If so, I'm not sure how pcim_iomap_wc() fits into the picture. A driver
can call both pcim_iomap_wc() and arch_phys_wc_add(), but the driver
doesn't explicitly do the unmap, so where would the arch_phys_wc_del()
happen?
If not, how does a driver know whether it should call arch_phys_wc_add()?
> ...
> /**
> + * pcim_iomap_wc_regions - Request and iomap PCI BARs with write-combining
> + * @pdev: PCI device to map IO resources for
> + * @mask: Mask of BARs to request and iomap
> + * @name: Name used when requesting regions
> + *
> + * Request and iomap regions specified by @mask with a preference for
> + * write-combining.
> + */
> +int pcim_iomap_wc_regions(struct pci_dev *pdev, int mask, const char *name)
> +{
> + void __iomem * const *iomap;
> + int i, rc;
> +
> + iomap = pcim_iomap_table(pdev);
> + if (!iomap)
> + return -ENOMEM;
> +
> + for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
> + unsigned long len;
> +
> + if (!(mask & (1 << i)))
> + continue;
> +
> + rc = -EINVAL;
> + len = pci_resource_len(pdev, i);
> + if (!len)
> + goto err_inval;
> +
> + rc = pci_request_region(pdev, i, name);
> + if (rc)
> + goto err_inval;
> +
> + rc = -ENOMEM;
> + if (!pcim_iomap_wc(pdev, i, 0))
> + goto err_region;
Is there a user for this? Are there really devices where *all* the BARs
can be mapped with WC? Are there enough of them to make it worth adding
this?
I don't see users of either pcim_iomap_wc() or pcim_iomap_wc_regions() so
far. Did I miss them, or do you just expect them in the near future?
Bjorn
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