Hi Tom,
On 23.08.20 16:03, Tom Rini wrote:
On Sun, Aug 23, 2020 at 11:41:41AM +0200, Stefan Roese wrote:
Hi Simon,
Hi Tom,
On 22.08.20 17:09, Simon Glass wrote:
Hi Stefan,
On Fri, 14 Aug 2020 at 05:40, Stefan Roese <s...@denx.de> wrote:
Hi Simon,
On 04.08.20 17:05, Simon Glass wrote:
<snip>
Changes in v1:
- Change patch subject
- Enhance Kconfig help descrition
- Use if() instead of #if
drivers/pci/Kconfig | 10 ++++++++++
drivers/pci/pci-uclass.c | 9 ++++++---
2 files changed, 16 insertions(+), 3 deletions(-)
This needs an update to a sandbox test to handle this behaviour.
Okay. But how should I handle all these defconfig changes with regard
to the other patches in this series, introducing multiple new PCI
related Kconfig options. With 3 new Kconfig options, all permutations
would lead to 8 (2 ^ 3) different defconfig files. This does not
scale.
I might be missing something here though - perhaps this is easier to
achieve.
For sandbox, turn on all options and then add a new PCI bus that uses
this functionality. If there are lots of combinations you could add 8
new buses, but I'm hoping that isn't necessary?
If I turn on all new options, sandbox will run with these new options
enabled. I don't know with with implications, as it usually runs with
the "normal" PCI related Kconfig options. Also the "normal" PCI
defconfig (e.g. CONFIG_PCI_REGION_MULTI_ENTRY etc disabled) will not
be tested any more via the sandbox tests. So you get either a test for
the new Kconfig option enabled or disabled this way.
Do you really want me to do this?
So the Kconfig completely changes the implementation of PCI? That
doesn't make it very testable, as you say.
Instead, I think the Kconfig should enable the option, then use one of
three ways to select the option:
- a device tree property (on sandbox particularly)
- compatible string (where the property is not appropriate
- setting a flag in PCI bus (where a driver requires the option be selected)
That way you can write a test for the new feature in sandbox, without
deleting all the other tests.
Coming back to this issue after some time - sorry for the delay.
I'm not sure, if I understand this correctly. Do you suggest that the
driver code (in this case pci-uclass.c) should be extended to support
this (sandbox) testing support?
Not really. I see these things as features that drivers can enable /
disable depending on their needs. If that is correct, then sandbox is
no different form other drivers, except that perhaps it might support
all combinations rather than just one.
If yes, I really think that this is counterproductive. As we added (at
least some of) the Kconfig options explicitly, to not add code to
pci-uclass.c in the "normal case". So adding code to e.g. check a device
tree property or a compatible string would increase the code size again.
How about some flags in struct pci_controller?
If not, I'm still unsure how you would like to test the "normal case",
e.g. with CONFIG_PCI_REGION_MULTI_ENTRY disabled, and with it enabled
without adding more sandbox build targets, with all the Kconfig options
permutations. As the extra code (in pci-uclass) is either included or
not in the sandbox binary.
Kconfig enables and disables the feature by adding the code. But we
can still have a flag to determine whether it is used by a particular
driver. That way we can keep our test coverage.
But after adding one test for the first of these pci-uclass related
patches, I do have a general comment on this. I find it quite complex
and time consuming to add these tests. Don't get me wrong, I agree in
general, that having tests in U-Boot is very good. But enforcing tests
for each and every new feature addition in drivers (layers) like PCI
seems a bit too much to me. For example new features like the "pci:
pci-uclass: Add support for Single-Root I/O Virtualization" would mean
AFAIU, that I need to write some emulation code for such a PCI device
and also some testing driver matching such a device, since we have no
real hardware like this in sandbox. This would result in much more
complex code for this test & emulation compared to the driver change /
extension.
Yes but it is not that hard. There are a few PCI emulation devices in
U-Boot and these form the basis of existing tests. Before this, we
really had no tests for PCI and even the behaviour was largely
undefined. Your ability to convert the regions[] array to a
dynamically allocated array is partly thanks to these tets.
To sum it up, I'm asking if you still think that adding tests for all
those PCI driver extensions is really necessary for upstream acceptance?
What's your opinion on this? Do you understand my position on this?
I don't want to be silly about it, but in general if we add new
features, particularly to core features, I think there should be
tests.
As mentioned before, I agree in general. But we should be not too
strict here IMHO, to enforce new tests for each and every U-Boot
addition. It's probably not easy to draw the line here to decide,
when and when not to enforce tests. Perhaps this should reflect the
complexitiy of the test code and also the user count of the new
U-Boot code / features (here its solely Octeon TX/TX2).
Apart from correctness, they also define the behaviour of the
code, in many cases. The test you added in one patch looks good, and
doesn't look too complicated.
Yes, that one was quite simple. But emulating special PCI device
capabilities to enable such virtual testings will be much more complex,
AFAICT. If it would be "easy", I would not argue with you on this and
just implement these tests and be done with it. ;) But frankly, I have
no real idea (without digging much deeper into this) on how to add these
emulation codes and tests in a way, that they completely test all the
feature additions. Please note that I'm not the original author of these
additions.
Of course it is more than zero work. But
so much of the refactoring we do in U-Boot these days would be much
harder and error-prone without these tests.
+Tom Rini who might want to weigh in.
Tom, are you okay with going forward with these PCIe related patches,
without adding test cases for all PCI feature additions? Which would
mean to add very special PCI device emulation and test drivers for
such devices? The PCI extensions are not that intrusive and AFAICT
Simon is okay with all of them in general, only would like to have tests
for all driver extensions.
For complex hardware specific things like this and testing I think we'll
have the most luck by, when possible and I'm not sure we do enough
today, enable features and tests on qemu* machines and get it that way,
rather than writing new emulators for sandbox.
I agree. As was proved by the QEMU Nokia test a few days ago with the
bi_memstart (etc) cleanup, I'm working on. I also had the idea that such
an QEMU machine emulation would be much better. Let me check, if any
such machine emulation is possible for Octeon TX/TX2. I'll get back to
this, once I have more informations here.
In the meantime, how do we proceeed with this current Octeon TX/TX2
patchset? I would really like to get at least some of it included
into mainline soon. The first RFC version has been posted to the list
by Suneel end of October last year, so more than 3/4 of a year ago.
My proposal would be (if nobody objects), to push the PCI patches
and Octeon TX/TX2 base port into mainline, dropping the really big
drivers (nand & ethernet) for now, which need a bit more review IMHO.
Should I continue this way?
Thanks,
Stefan
