From: Ming Wang wangming01@loongson.cn
LoongArch inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IAZ3M1
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This is similar to commit 62b6dee1b44a ("PCI/portdrv: Prevent LS7A Bus Master clearing on shutdown"), which prevents LS7A Bus Master clearing on kexec.
The key point of this is to work around the LS7A defect that clearing PCI_COMMAND_MASTER prevents MMIO requests from going downstream, and we may need to do that even after .shutdown(), e.g., to print console messages. And in this case we rely on .shutdown() for the downstream devices to disable interrupts and DMA.
Only skip Bus Master clearing on bridges because endpoint devices still need it.
Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Ming Wang wangming01@loongson.cn --- drivers/pci/pci-driver.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index 9c59bf03d657..b699839a7d4f 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -526,7 +526,11 @@ static void pci_device_shutdown(struct device *dev) * If it is not a kexec reboot, firmware will hit the PCI * devices with big hammer and stop their DMA any way. */ +#ifdef CONFIG_LOONGARCH + if (kexec_in_progress && !pci_is_bridge(pci_dev) && (pci_dev->current_state <= PCI_D3hot)) +#else if (kexec_in_progress && (pci_dev->current_state <= PCI_D3hot)) +#endif pci_clear_master(pci_dev); }