From: Marek Behún <kabel@xxxxxxxxxx> commit 7a41ae80bdcb17e14dd7d83239b8a0cf368f18be upstream. The pci_bridge_emul_conf_write() function correctly clears W1C bits in cfgspace cache, but it does not inform the underlying implementation about the clear request: the .write_op() method is given the value with these bits cleared. This is wrong if the .write_op() needs to know which bits were requested to be cleared. Fix the value to be passed into the .write_op() method to have requested W1C bits set, so that it can clear them. Both pci-bridge-emul users (mvebu and aardvark) are compatible with this change. Link: https://lore.kernel.org/r/20211028185659.20329-2-kabel@xxxxxxxxxx Fixes: 23a5fba4d941 ("PCI: Introduce PCI bridge emulated config space common logic") Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> Signed-off-by: Marek Behún <kabel@xxxxxxxxxx> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/pci/pci-bridge-emul.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/drivers/pci/pci-bridge-emul.c +++ b/drivers/pci/pci-bridge-emul.c @@ -431,8 +431,21 @@ int pci_bridge_emul_conf_write(struct pc /* Clear the W1C bits */ new &= ~((value << shift) & (behavior[reg / 4].w1c & mask)); + /* Save the new value with the cleared W1C bits into the cfgspace */ cfgspace[reg / 4] = cpu_to_le32(new); + /* + * Clear the W1C bits not specified by the write mask, so that the + * write_op() does not clear them. + */ + new &= ~(behavior[reg / 4].w1c & ~mask); + + /* + * Set the W1C bits specified by the write mask, so that write_op() + * knows about that they are to be cleared. + */ + new |= (value << shift) & (behavior[reg / 4].w1c & mask); + if (write_op) write_op(bridge, reg, old, new, mask);
