Hi Bjorn, On 08/02/19 2:22 AM, Bjorn Helgaas wrote: > In the subject, "legacy_irq_handler" looks like it's supposed to be a > function name, but it's not. Maybe something like: > > PCI: keystone: Check INTA/B/C/D IRQ_STATUS in ks_pcie_legacy_irq_handler() > > On Thu, Feb 07, 2019 at 04:39:17PM +0530, Kishon Vijay Abraham I wrote: >> The legacy interrupt handler directly checks the IRQ_STATUS register >> corresponding to a interrupt line inorder to invoke generic_handle_irq. > > s/The legacy interrupt handler/ks_pcie_handle_legacy_irq()/ ? > s/to a/to an/ > s/inorder/in order/ > s/generic_handle_irq/generic_handle_irq()/ > >> While this is okay for K2G platform which has separate interrupt line for >> each of the 4 legacy interrupts, AM654 which uses the same PCIe wrapper >> has a single interrupt line for all the legacy interrupts. So for AM654 >> the interrupt handler won't be able to directly check the IRQ_STATUS >> register corresponding to the interrupt line. > > s/platform which/platform, which/ > s/separate interrupt line/separate interrupt lines/ > s/AM654 which/AM654, which/ > s/PCIe wrapper/PCIe wrapper,/ > s/interrupt line for all/interrupt line shared by all/ > > >> Also the legacy interrupt handler uses 'virq' obtained from >> irq_of_parse_and_map to find the correct interrupt line which raised the >> interrupt. There is no guarantee that virq assigned for contiguous hardware >> irq will be contiguous and the interrupt handler might end up checking >> the wrong IRQ_STATUS register. > > s/irq_of_parse_and_map/irq_of_parse_and_map() > s/irq will/IRQ will/ > >> In order to overcome the above issues, read the IRQ_STATUS register of >> all the 4 legacy interrupts to determine which interrupt was raised. >> >> Link: https://lkml.kernel.org/r/bb081d21-7c03-0357-4294-7e92d95d838c@xxxxxxx >> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> >> --- >> drivers/pci/controller/dwc/pci-keystone.c | 22 ++++++++++++---------- >> 1 file changed, 12 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c >> index 5286a480f76b..4cf9849d5a1d 100644 >> --- a/drivers/pci/controller/dwc/pci-keystone.c >> +++ b/drivers/pci/controller/dwc/pci-keystone.c >> @@ -214,16 +214,11 @@ static void ks_pcie_handle_legacy_irq(struct keystone_pcie *ks_pcie, >> { >> struct dw_pcie *pci = ks_pcie->pci; >> struct device *dev = pci->dev; >> - u32 pending; >> int virq; >> >> - pending = ks_pcie_app_readl(ks_pcie, IRQ_STATUS(offset)); >> - >> - if (BIT(0) & pending) { >> - virq = irq_linear_revmap(ks_pcie->legacy_irq_domain, offset); >> - dev_dbg(dev, ": irq: irq_offset %d, virq %d\n", offset, virq); >> - generic_handle_irq(virq); >> - } >> + virq = irq_linear_revmap(ks_pcie->legacy_irq_domain, offset); >> + dev_dbg(dev, ": irq: irq_offset %d, virq %d\n", offset, virq); >> + generic_handle_irq(virq); >> >> /* EOI the INTx interrupt */ >> ks_pcie_app_writel(ks_pcie, IRQ_EOI, offset); >> @@ -607,8 +602,9 @@ static void ks_pcie_legacy_irq_handler(struct irq_desc *desc) >> struct keystone_pcie *ks_pcie = irq_desc_get_handler_data(desc); >> struct dw_pcie *pci = ks_pcie->pci; >> struct device *dev = pci->dev; >> - u32 irq_offset = irq - ks_pcie->legacy_host_irqs[0]; >> struct irq_chip *chip = irq_desc_get_chip(desc); >> + unsigned int irq_no; >> + u32 reg; >> >> dev_dbg(dev, ": Handling legacy irq %d\n", irq); >> >> @@ -618,7 +614,13 @@ static void ks_pcie_legacy_irq_handler(struct irq_desc *desc) >> * ack operation. >> */ >> chained_irq_enter(chip, desc); >> - ks_pcie_handle_legacy_irq(ks_pcie, irq_offset); >> + for (irq_no = 0; irq_no < PCI_NUM_INTX; irq_no++) { >> + reg = ks_pcie_app_readl(ks_pcie, IRQ_STATUS(irq_no)); >> + if (!(reg & INTx_EN)) >> + continue; >> + ks_pcie_handle_legacy_irq(ks_pcie, irq_no); > > It's too bad that reading IRQ_STATUS and writing IRQ_EOI are now in > separate functions. It's nice to have them together for code auditing > purposes. > > Could maybe accumulate a mask of which INTx bits are set and call > ks_pcie_handle_legacy_irq() only once with that mask? Of course, then > you'd need another loop in ks_pcie_handle_legacy_irq(). Patch "5" of this series "PCI: keystone: Cleanup ks_pcie_msi_irq_handler and ks_pcie_legacy_irq_handler" does more cleanup in irq handler and there ks_pcie_handle_legacy_irq is removed and everything is done in a single function. I have to anyway revisit legacy irq handler and have some of the register writes move to proper irq_chip callbacks as Lorenzo commented in [1] [1] -> https://lkml.org/lkml/2019/1/24/333 Thanks Kishon
