On Wed, 2016-05-04 at 13:03 +0300, Andy Shevchenko wrote:

On Wed, May 4, 2016 at 12:51 PM, Bryan O'Donoghue
[off-list ref] wrote:

quoted

On Wed, 2016-05-04 at 12:42 +0300, Andy Shevchenko wrote:

quoted

On Wed, May 4, 2016 at 12:31 PM, Bryan O'Donoghue
[off-list ref] wrote:

quoted

Andy,

If you are going to start removing working PCI devices from the
PCI
config table in favour of a shim in SERIAL_8250_LPSS then the
very
minimum should be some sort of dependency link between
SERIAL_8250_LPSS
and CONFIG_SERIAL_8250_PCI in kconfig.

A user could reasonably read the QRK datasheet - switch on
CONFIG_SERIAL_8250_PCI and then wonder why no console output
happened
on boot. S/he shouldn't have to know that devices were moved
from
the
PCI driver to an LPSS shim driver or that the 8250_lpss driver
now
needs to be selected instead of the intuitively correct
8250_pci
driver.

That is taken care of since default is set to SERIAL_8250 (you
even
don't need to have PCI driver enabled!).
Doesn't work for you?

The default may be set to SERIAL_8250 but, without the QRK specific
entry in 8250_pci.c you won't get console output.

So if you are going to remove the QRK entry from 8250_pci.c and
stuff
it into 8250_lpss.c then 8250_lpss needs to be selected by
CONFIG_SERIAL_8250_PCI.

Why?!

Now it should be enough to have SERIAL_8250 set to non-n to have
8250_lpss compiled.
Can you check it?

I'm sure that's true.

My point to you is that - its a highly non-intuitive thing to do on a
reading of the datasheet for this part.

LPSS is, ostensibly at least, for passing processor resources via APCI.

If you look at a QRK datasheet it says "enumerate all this stuff via
PCI" - there's not a single mention of LPSS. Its reasonable, correct
and currently required for QRK to set CONFIG_8250_PCI.

To move away from a valid/standard PCI probe routine into a new special
LPSS/PCI shim (which the hardware doesn't actually mandate) I do think
you should to setup the dependency CONFIG_8250_PCI => CONFIG_8250_LPSS.

---
bod