Hi Gavin,
On 2016/7/1 8:50, Gavin Shan wrote:
On Thu, Jun 30, 2016 at 06:53:09PM +0800, Yongji Xie wrote:
We should not disable memory decoding when we reassign alignment
in pci_reassigndev_resource_alignment(). It's meaningless and
have some side effect. For example, some fixup functions such as
quirk_e100_interrupt() read PCI_COMMAND_MEMORY to know whether
the devices has been initialized by the firmware or not. If we
disable memory decoding here, these functions will get a wrong
information that the devices was not initialized by the firmware
which may cause a wrong fixup. Besides, disabling memory decoding
may also break some devices that need to have memory decoding
always-on during probing.
It seems the changelog isn't correct enough if it's talking about
below check in code:
if (!(command & PCI_COMMAND_MEMORY) || !pci_resource_start(dev, 0))
return;
Could you give me more details? It seems that we couldn't disable
e100 interrupts which enabled by some firmware if we disabling
memory decoding here.
Signed-off-by: Yongji Xie <xyjxie@xxxxxxxxxxxxxxxxxx>
---
drivers/pci/pci.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6ae02de..6241cfc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4820,7 +4820,6 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
int i;
struct resource *r;
resource_size_t align, size;
- u16 command;
/* We should never try to reassign VF's alignment */
if (dev->is_virtfn)
@@ -4838,12 +4837,7 @@ void pci_reassigndev_resource_alignment(struct pci_dev *dev)
return;
}
- dev_info(&dev->dev,
- "Disabling memory decoding and releasing memory resources.\n");
- pci_read_config_word(dev, PCI_COMMAND, &command);
- command &= ~PCI_COMMAND_MEMORY;
- pci_write_config_word(dev, PCI_COMMAND, command);
-
+ dev_info(&dev->dev, "Releasing memory resources.\n");
Is there a problem you found with PCI_COMMAND removed? If so, could you
please share more details, thanks.
Disabling memory decoding may break some devices which
have flag mmio_always_on. Besides the mmio_always_on case,
I also found this would break some P2P bridge such as
PEX 8718 controller.
Thanks,
Yongji
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