Re: [RESEND PATCH v2] PCI: dwc: Round up num_ctrls if num_vectors is less than MAX_MSI_IRQS_PER_CTRL

[Lorenzo Pieralisi <lpieralisi@kernel.org>]

On Fri, Feb 03, 2023 at 04:23:53PM +0800, Shawn Lin wrote:
> On 2022/11/23 6:04, Han Jingoo wrote:
> > On Mon, Nov 21, 2022 Shawn Lin <shawn.lin@rock-chips.com> wrote:
> > > 
> > > Some SoCs may only support 1 RC with a few MSIs support that the total number 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.
> > > 
> > > Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> > 
> > Acked-by: Jingoo Han <jingoohan1@gmail.com>
> 
> Thanks, Jingoo!
> 
> Hi Lorenzo,
> 
> Is there any chance this patch be applied? :)
> 
> > 
> > Best regards,
> > Jingoo Han
> > 
> > > ---
> > > 
> > > Changes in v2:
> > > - set num_ctrls to 1 if it's less than one
> > > 
> > >   drivers/pci/controller/dwc/pcie-designware-host.c | 6 ++++++
> > >   1 file changed, 6 insertions(+)
> > > 
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > index 39f3b37..cfce1e0 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > @@ -62,6 +62,8 @@ irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp)
> > >          struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > > 
> > >          num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;

I assume that if pp->num_vectors > MAX_MSI_IRQS_PER_CTRL but not
an exact multiple we would have the same problem right ?

Best to fix it for both cases.

Lorenzo

> > > +       if (num_ctrls < 1)
> > > +               num_ctrls = 1;
> > > 
> > >          for (i = 0; i < num_ctrls; i++) {
> > >                  status = dw_pcie_readl_dbi(pci, PCIE_MSI_INTR0_STATUS +
> > > @@ -343,6 +345,8 @@ 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;
> > > +       if (num_ctrls < 1)
> > > +               num_ctrls = 1;
> > > 
> > >          if (!pp->msi_irq[0]) {
> > >                  pp->msi_irq[0] = platform_get_irq_byname_optional(pdev, "msi");
> > > @@ -707,6 +711,8 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> > > 
> > >          if (pp->has_msi_ctrl) {
> > >                  num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> > > +               if (num_ctrls < 1)
> > > +                       num_ctrls = 1;
> > > 
> > >                  /* Initialize IRQ Status array */
> > >                  for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
> > > --
> > > 2.7.4
> > > 
> 
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