[RFC PATCH] serial: ns16550: Move PCI access from ofdata_to_platdata() to probe()

[Bin Meng]

On Thu, Feb 27, 2020 at 5:36 PM Bin Meng <bmeng.cn at gmail.com> wrote:
>
> On Tue, Feb 18, 2020 at 8:36 PM Wolfgang Wallner
> <wolfgang.wallner at 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 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 at 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
> >
> >  drivers/serial/ns16550.c | 26 +++++++++++++-------------
> >  1 file changed, 13 insertions(+), 13 deletions(-)
> >
>
> Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
>
> This fixed the boot failure of Intel Galileo
>
> Tested on Intel Galileo
> Tested-by: Bin Meng <bmeng.cn at gmail.com>

applied to u-boot-x86, thanks!