[sync] PR-941: LoongArch: fix 2k500 sfb driver not work during reboot · Pull Request !1008 · openEuler/kernel

### 1. Origin pull request:
https://gitee.com/openeuler/kernel/pulls/941

### 2. Original pull request related issue(s):
https://gitee.com/openeuler/kernel/issues/I7BC4C

### 3. Original pull request related commit(s):
| Sha | Datetime | Message |
|---|---|---|
|[cb7f300f](https://gitee.com/openeuler/kernel/commits/cb7f300fcc9eb75612680212d2bb241ff13ca82a)|2023-02-01 12:30:17 +0800 CST|PCI/portdrv: Prevent LS7A Bus Master clearing on shutdown stable inclusion from stable-v6.3-rc1 commit 	62b6dee1b44aa23b3935543aff7df80399ec726b category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7BC4C Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/pci/pcie/portdrv.c?h=v6.3.6&id=62b6dee1b44aa23b3935543aff7df80399ec726b -------------------------------- After cc27b735ad3a ("PCI/portdrv: Turn off PCIe services during shutdown") we observe hangs during poweroff/reboot on systems with LS7A chipset. This happens because the portdrv .shutdown() method (pcie_portdrv_remove()) clears PCI_COMMAND_MASTER via pci_disable_device(), which prevents bridges from forwarding memory or I/O Requests in the upstream direction (PCIe r6.0, sec 7.5.1.1.3). LS7A Root Ports have a hardware defect: clearing PCI_COMMAND_MASTER *also* prevents the bridge from forwarding CPU MMIO requests in the downstream direction, and these MMIO accesses to devices below the bridge happen even after .shutdown(), e.g., to print console messages. LS7A neither forwards the requests nor sends an unsuccessful completion to the CPU, so the CPU waits forever, resulting in the hang. The purpose of .shutdown() is to disable interrupts and DMA from the device. PCIe ports may generate interrupts (either MSI/MSI-X or INTx) for AER, DPC, PME, hotplug, etc., but they never perform DMA except MSI/MSI-X. Clearing PCI_COMMAND_MASTER effectively disables MSI/MSI-X, but not INTx. The port service driver .remove() methods clear the interrupt enables in PCI_ERR_ROOT_COMMAND, PCI_EXP_DPC_CTL, PCI_EXP_SLTCTL, and PCI_EXP_RTCTL, etc., which disables interrupts regardless of whether they are MSI/MSI-X or INTx. Add a pcie_portdrv_shutdown() method that calls all the port service driver .remove() methods to clear the interrupt enables for each service but does not clear Bus Mastering on the port itself. [bhelgaas: commit log] Link: https://lore.kernel.org/r/20230201043018.778499-2-chenhuacai@loongson.cn Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn> |
|[b70cfc41](https://gitee.com/openeuler/kernel/commits/b70cfc4119b1dcc92f36f463ab51ef64eab39a42)|2023-06-06 15:09:32 +0800 CST|Revert "PCI: Add quirk for LS7A to avoid reboot failure" LoongArch inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7BC4C -------------------------------- This reverts commit cea488db09739fb64cda496e313e6940c7cb42c2. Signed-off-by: Hongchen Zhang <zhanghongchen@loongson.cn> |

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