On 8/22/2017 2:28 PM, Markus Theil wrote:
> This patch adds MSI IRQ mode and in a way, that should
> also work on older kernel versions. The base for my patch
> was an attempt to do this in cf705bc36c which was later reverted in
> d8ee82745a. Compilation was tested on Linux 3.2, 4.10 and 4.12.
>
> MSI(X) setup was already using pci_alloc_irq_vectors before,
> but calls to pci_free_irq_vectors were missing and added.
Overall looks good to me, would you mind splitting this into multiple
patches:
1- Create igbuio_pci_enable_interrupts() and
igbuio_pci_disable_interrupts() functions without changing anything
2- Add pci_free_irq_vectors()
3- add MSI support
>
> Signed-off-by: Markus Theil <markus.th...@tu-ilmenau.de>
<...>
> +/*
> + * It masks the msi on/off of generating MSI messages.
> + */
> +static void
> +igbuio_msi_mask_irq(struct pci_dev *pdev, struct msi_desc *desc, int32_t
> state> +{
> + u32 mask_bits = desc->masked;
> + u32 offset = desc->irq - pdev->irq;
> + u32 mask = 1 << offset;
> + u32 flag = !!state << offset;
> +
> + if (!desc->msi_attrib.maskbit)
> + return;
> +
> + mask_bits &= ~mask;
> + mask_bits |= flag;
> +
> + if (mask_bits != desc->masked) {
> + pci_write_config_dword(pdev, desc->mask_pos, mask_bits);
> + desc->masked = mask_bits;
> + }
I am not familiar with details of this function, is there a sample usage
in kernel that can help understanding it?
> +}
> +
> /**
> * This is the irqcontrol callback to be registered to uio_info.
> * It can be used to disable/enable interrupt from user space processes.
> @@ -146,6 +170,16 @@ igbuio_pci_irqcontrol(struct uio_info *info, s32
> irq_state)
> list_for_each_entry(desc, &pdev->dev.msi_list, list)
> igbuio_msix_mask_irq(desc, irq_state);
> #endif
> + } else if (udev->mode == RTE_INTR_MODE_MSI) {
> + struct msi_desc *desc;
Since two if block is using this, I think this can be moved to function
scope.
> +
> +#if (LINUX_VERSION_CODE < KERNEL_VERSION(4, 3, 0))
Can you please move version check to the compat.h? I am aware this
version check is there for msix, but since we are doubling it, it can be
good time to fix both.
> + list_for_each_entry(desc, &pdev->msi_list, list)> +
> igbuio_msi_mask_irq(pdev, desc, irq_state);
This walks on same list (msi_list) with above msix code. Is there a way
to say if this msi_desc for MSI or MSIx interrupts, how
igbuio_msi_mask_irq() will distinguish them?
> +#else
> + list_for_each_entry(desc, &pdev->dev.msi_list, list)
> + igbuio_msi_mask_irq(pdev, desc, irq_state);
> +#endif
> }
> pci_cfg_access_unlock(pdev);
>
> @@ -309,6 +343,91 @@ igbuio_pci_release_iomem(struct uio_info *info)
> }
>
> static int
> +igbuio_pci_enable_interrupts(struct rte_uio_pci_dev *udev)
> +{
> + int err = 0;
> +#ifdef HAVE_PCI_ENABLE_MSIX
> + struct msix_entry msix_entry;
> +#endif
> +
> + switch (igbuio_intr_mode_preferred) {
> + case RTE_INTR_MODE_MSIX:
> + /* Only 1 msi-x vector needed */
> +#ifdef HAVE_PCI_ENABLE_MSIX
> + msix_entry.entry = 0;
> + if (pci_enable_msix(udev->pdev, &msix_entry, 1) == 0) {
> + dev_dbg(&udev->pdev->dev, "using MSI-X");
> + udev->info.irq_flags = IRQF_NO_THREAD;
> + udev->info.irq = msix_entry.vector;
> + udev->mode = RTE_INTR_MODE_MSIX;
> + break;
> + }
> +#else
> + if (pci_alloc_irq_vectors(udev->pdev, 1, 1, PCI_IRQ_MSIX) == 1)
> {
> + dev_dbg(&udev->pdev->dev, "using MSI-X");
> + udev->info.irq = pci_irq_vector(udev->pdev, 0);
> + udev->mode = RTE_INTR_MODE_MSIX;
> + break;
> + }
> +#endif
Please add fall back comment: /* fall back to MSI */
And related this fallback, previously flow was:
Try MSIX, if fails try legacy.
Now it is:
Try MSIX, if fails try MSI, if fails try legacy.
Do you think, does this new step included may break anyone's out that
would expect to fallback to legacy? (although I don't expect, I believe
good to sound it)
> + case RTE_INTR_MODE_MSI:
> +#ifdef HAVE_PCI_ENABLE_MSI
> + if (pci_enable_msi(udev->pdev) == 0) {
> + dev_dbg(&udev->pdev->dev, "using MSI");
> + udev->info.irq_flags = IRQF_NO_THREAD;
> + udev->info.irq = udev->pdev->irq;
> + udev->mode = RTE_INTR_MODE_MSI;
> + break;
> + }
> +#else
> + if (pci_alloc_irq_vectors(udev->pdev, 1, 1, PCI_IRQ_MSI) == 1) {
> + dev_dbg(&udev->pdev->dev, "using MSI");
> + udev->info.irq = pci_irq_vector(udev->pdev, 0);
> + udev->mode = RTE_INTR_MODE_MSI;
> + break;
> + }
> +#endif
> + /* fall back to INTX */
> + case RTE_INTR_MODE_LEGACY:
> + if (pci_intx_mask_supported(udev->pdev)) {
> + dev_dbg(&udev->pdev->dev, "using INTX");
> + udev->info.irq_flags = IRQF_SHARED | IRQF_NO_THREAD;
> + udev->info.irq = udev->pdev->irq;
> + udev->mode = RTE_INTR_MODE_LEGACY;
> + break;
> + }
> + dev_notice(&udev->pdev->dev, "PCI INTX mask not supported\n");
> + /* fall back to no IRQ */
> + case RTE_INTR_MODE_NONE:
> + udev->mode = RTE_INTR_MODE_NONE;
> + udev->info.irq = 0;
> + break;
> +
> + default:
> + dev_err(&udev->pdev->dev, "invalid IRQ mode %u",
> + igbuio_intr_mode_preferred);
> + err = -EINVAL;
> + }
> +
> + return err;
> +}
<...>
