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

[Shawn Lin]

On 2022/11/22 7:54, Han Jingoo wrote:
> 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.
> 

Yes we have one such platform. Will set it to one as your comment.

Thanks.

> 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
>>