On Thu, 2024-10-24 at 17:43 +0200, Takashi Iwai wrote:

On Thu, 24 Oct 2024 10:02:59 +0200,
Philipp Stanner wrote:

quoted

On Wed, 2024-10-23 at 17:03 +0200, Takashi Iwai wrote:

quoted

On Wed, 23 Oct 2024 15:50:09 +0200,
Philipp Stanner wrote:

quoted

On Tue, 2024-10-22 at 16:08 +0200, Takashi Iwai wrote:

quoted

On Tue, 15 Oct 2024 20:51:12 +0200,
Philipp Stanner wrote:

quoted

pci_intx() is a hybrid function which can sometimes be
managed
through
devres. To remove this hybrid nature from pci_intx(), it is
necessary to
port users to either an always-managed or a never-managed
version.

hda_intel enables its PCI-Device with pcim_enable_device().
Thus,
it needs
the always-managed version.

Replace pci_intx() with pcim_intx().

Signed-off-by: Philipp Stanner <redacted>
---
 sound/pci/hda/hda_intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/pci/hda/hda_intel.c

b/sound/pci/hda/hda_intel.c
index b4540c5cd2a6..b44ca7b6e54f 100644

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c

@@ -786,7 +786,7 @@ static int azx_acquire_irq(struct azx

*chip,
int do_disconnect)
 	}
 	bus->irq = chip->pci->irq;
 	chip->card->sync_irq = bus->irq;
-	pci_intx(chip->pci, !chip->msi);
+	pcim_intx(chip->pci, !chip->msi);
 	return 0;
 }
 

Hm, it's OK-ish to do this as it's practically same as what
pci_intx()
currently does.  But, the current code can be a bit
inconsistent
about
the original intx value.  pcim_intx() always stores !enable
to
res->orig_intx unconditionally, and it means that the
orig_intx
value
gets overridden at each time pcim_intx() gets called.

Yes.

quoted

Meanwhile, HD-audio driver does release and re-acquire the
interrupt
after disabling MSI when something goes wrong, and pci_intx()
call
above is a part of that procedure.  So, it can rewrite the
res->orig_intx to another value by retry without MSI.  And
after
the
driver removal, it'll lead to another state.

I'm not sure that I understand this paragraph completely.
Still,
could
a solution for the driver on the long-term just be to use
pci_intx()?

pci_intx() misses the restore of the original value, so it's no
long-term solution, either.

Sure that is missing – I was basically asking whether the driver
could
live without that feature.

Consider that point obsolete, see below

quoted

What I meant is that pcim_intx() blindly assumes the negative of
the
passed argument as the original state, which isn't always true. 
e.g.
when the driver calls it twice with different values, a wrong
value
may be remembered.

Ah, I see – thoguh the issue is when it's called several times with
the
*same* value, isn't it?

E.g.

pcim_intx(pdev, 1); // 0 is remembered as the old value
pcim_intx(pdev, 1); // 0 is falsely remembered as the old value

Also, it would seem that calling the function for the first time
like
that:

pcim_intx(pdev, 0); // old value: 1

is at least incorrect, because INTx should be 0 per default,
shouldn't
it? Could then even be a 1st class bug, because INTx would end up
being
enabled despite having been disabled all the time.

Yeah, and the unexpected restore can happen even with a single call
of
pcim_intx(), if the driver calls it unnecessarily.

quoted

quoted

That said, I thought of something like below.

At first glance that looks like a good idea to me, thanks for
working
this out!

IMO you can submit that as a patch so we can discuss it separately.

Sure, I'm going to submit later.

I just took a look into the old implementation of pci_intx() (there was
no pcim_intx() back then), before I started cleaning up PCI's devres.
This what it looked like before
25216afc9db53d85dc648aba8fb7f6d31f2c8731:

void pci_intx(struct pci_dev *pdev, int enable)
{
	u16 pci_command, new;

	pci_read_config_word(pdev, PCI_COMMAND, &pci_command);

	if (enable)
		new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
	else
		new = pci_command | PCI_COMMAND_INTX_DISABLE;

	if (new != pci_command) {
		struct pci_devres *dr;

		pci_write_config_word(pdev, PCI_COMMAND, new);

		dr = find_pci_dr(pdev);
		if (dr && !dr->restore_intx) {
			dr->restore_intx = 1;
			dr->orig_intx = !enable;
		}
	}
}
EXPORT_SYMBOL_GPL(pci_intx);

If I'm not mistaken the old version did not have the problem because
the value to be restored only changed if new != pci_command.

That should always be correct, what do you think?

If so, only my commit 25216afc9db53d85dc648aba8fb7f6d31f2c8731 needs to
be fixed.

Thanks,
P.

thanks,

Takashi