[PATCH] PCI: dwc: Round up num_ctrls if num_vectors is less than MAX_MSI_IRQS_PER_CTRL

[Han Jingoo]

On Sun, Nov 20, 2022 Shawn Lin <shawn.lin at rock-chips.com> wrote:
>
> Some SoCs may only support 1 RC with a few MSIs support that the total numver of MSIs is
> less than MAX_MSI_IRQS_PER_CTRL. In this case, num_ctrls will be zero which fails setting
> up MSI support. Fix it by rounding up num_ctrls to at least one.

Hi Shawn Lin,

If you find only a single case (1RC with a few MSIs), please set it as one
if the divided value is zero.

For example,
num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
if (num_ctrls < 1)
    num_ctrls = 1

Best regards,
Jingoo Han

>
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
> ---
>
>  drivers/pci/controller/dwc/pcie-designware-host.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 39f3b37..2cba2a8 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -61,7 +61,7 @@ irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp)
>         irqreturn_t ret = IRQ_NONE;
>         struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>
> -       num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> +       num_ctrls = DIV_ROUND_UP(pp->num_vectors, MAX_MSI_IRQS_PER_CTRL);
>
>         for (i = 0; i < num_ctrls; i++) {
>                 status = dw_pcie_readl_dbi(pci, PCIE_MSI_INTR0_STATUS +
> @@ -342,7 +342,7 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
>
>         if (!pp->num_vectors)
>                 pp->num_vectors = MSI_DEF_NUM_VECTORS;
> -       num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> +       num_ctrls = DIV_ROUND_UP(pp->num_vectors, MAX_MSI_IRQS_PER_CTRL);
>
>         if (!pp->msi_irq[0]) {
>                 pp->msi_irq[0] = platform_get_irq_byname_optional(pdev, "msi");
> @@ -706,7 +706,7 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
>         dw_pcie_setup(pci);
>
>         if (pp->has_msi_ctrl) {
> -               num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> +               num_ctrls = DIV_ROUND_UP(pp->num_vectors, MAX_MSI_IRQS_PER_CTRL);
>
>                 /* Initialize IRQ Status array */
>                 for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
> --
> 2.7.4
>