On Mon, Mar 2, 2020 at 9:41 PM Wolfgang Wallner wolfgang.wallner@br-automation.com wrote:
Currently the ofdata_to_platdata() method calls dev_read_addr_pci(), which potentially accesses the parent PCI bus. If this happens before the parent PCI bus is probed the resulting address will be wrong.
This behavior was triggered by commit 82de42fa1468 ("dm: core: Allocate parent data separate from probing parent").
According to a comment in drivers/pci/pci-uclass.c [1] accessing the PCI parent bus in ofdata_to_platdata() is not allowed, and the access should be moved to the probe() function.
Move the call to dev_read_addr_pci() and the related handling of the 'addr' value from the ofdata_to_platdata() to its own function, which is then called from the probe() method.
While moving the code, the comment /* try Processor Local Bus device first */ was dropped. It was initially added with commit 3db886a5bf38 ("serial: ns16550: Support ns16550 compatible pci uart devices") and later made obsolete with commit 33c215af4b9d ("dm: pci: Add a function to read a PCI BAR").
[1] Comment in drivers/pci/pci-uclass.c: "A common cause of this problem is that this function is called in the ofdata_to_platdata() method of @dev. Accessing the PCI bus in that method is not allowed, since it has not yet been probed. To fix this, move that access to the probe() method of @dev instead."
Signed-off-by: Wolfgang Wallner wolfgang.wallner@br-automation.com
Fixes: 82de42fa1468 ("dm: core: Allocate parent data separate from probing parent")
The discussion leading to this patch is located at https://lists.denx.de/pipermail/u-boot/2020-February/399811.html
I have moved the code from probe() to a new function called ns1655_serial_set_base_addr() to keep the probe() simple.
Changes in v2:
- Fixed build guards
- Moved code from probe() to a new function called ns1655_serial_set_base_addr() to keep the probe() simple
- Removed RFC tag
drivers/serial/ns16550.c | 40 ++++++++++++++++++++++++++++------------ 1 file changed, 28 insertions(+), 12 deletions(-)
Reviewed-by: Bin Meng bmeng.cn@gmail.com Tested-by: Bin Meng bmeng.cn@gmail.com # Tested on Intel Galileo