Re: [PATCH net-next v3 2/3] net: stmmac: Add glue driver for Motorcomm YT6801 ethernet controller

Russell King (Oracle)
2025-11-24T19:06:43Z

On Mon, Nov 24, 2025 at 04:32:10PM +0000, Yao Zi wrote:
> +static int motorcomm_setup_irq(struct pci_dev *pdev,
> + struct stmmac_resources *res,
> + struct plat_stmmacenet_data *plat)
> +{
> + int ret;
> +
> + ret = pci_alloc_irq_vectors(pdev, 6, 6, PCI_IRQ_MSIX);
> + if (ret > 0) {
> + res->rx_irq[0] = pci_irq_vector(pdev, 0);
> + res->tx_irq[0] = pci_irq_vector(pdev, 4);
> + res->irq = pci_irq_vector(pdev, 5);
> +
> + plat->flags |= STMMAC_FLAG_MULTI_MSI_EN;
> +
> + return 0;
> + }
> +
> + dev_info(&pdev->dev, "failed to allocate MSI-X vector: %d\n", ret);
> + dev_info(&pdev->dev, "try MSI instead\n");
> +
> + ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> + if (ret < 0)
> + return dev_err_probe(&pdev->dev, ret,
> + "failed to allocate MSI\n");
> +
> + res->irq = pci_irq_vector(pdev, 0);
> +
> + return 0;
> +}
> +
> +static int motorcomm_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> +{
...
> + ret = motorcomm_setup_irq(pdev, &res, plat);
> + if (ret)
> + return dev_err_probe(&pdev->dev, ret, "failed to setup IRQ\n");
> +
> + motorcomm_init(priv);
> +
> + res.addr = priv->base + GMAC_OFFSET;
> +
> + return stmmac_dvr_probe(&pdev->dev, plat, &res);

If stmmac_dvr_probe() fails, then it will return an error code. This
leaves the PCI MSI interrupt allocated...

> +}
> +
> +static void motorcomm_remove(struct pci_dev *pdev)
> +{
> + stmmac_dvr_remove(&pdev->dev);
> + pci_free_irq_vectors(pdev);

... which stood out because of the presence of this function doing
stuff after the call to stmmac_dvr_remove().

So... reviewing the other stmmac PCI drivers:

- dwmac-intel calls pci_alloc_irq_vectors() but does not call
pci_free_irq_vectors(). This looks like a bug.
- dwmac-intel calls pcim_enable_device() in its probe function, and
also its intel_eth_pci_resume() - pcim_enable_device() is the devres
managed function, so we end up adding more and more devres entries
each time intel_eth_pci_resume() is resumed. Note that
intel_eth_pci_suspend() doesn't disable the device. So, this should
probably be the non-devres version.
- dwmac-loongson looks sane, but the checks for ld->multichan before
calling loongson_dwmac_msi_clear() look unnecessary, as
pci_free_irq_vectors() can be safely called even if MSI/MSI-X have
not been (successfully) allocated.

So, I wonder whether there is scope to have a common way to clean up
PCI drivers. Could you look into this please?

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!