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Message-ID: <87ttd2276j.wl-tiwai@suse.de>
Date: Wed, 23 Oct 2024 17:03:00 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Philipp Stanner <pstanner@...hat.com>
Cc: Takashi Iwai <tiwai@...e.de>, Damien Le Moal <dlemoal@...nel.org>,
Niklas Cassel <cassel@...nel.org>, Sergey Shtylyov <s.shtylyov@....ru>,
Basavaraj Natikar <basavaraj.natikar@....com>, Jiri Kosina
<jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>, Arnd Bergmann
<arnd@...db.de>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Alex
Dubov <oakad@...oo.com>, Sudarsana Kalluru <skalluru@...vell.com>, Manish
Chopra <manishc@...vell.com>, "David S. Miller" <davem@...emloft.net>, Eric
Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo
Abeni <pabeni@...hat.com>, Rasesh Mody <rmody@...vell.com>,
GR-Linux-NIC-Dev@...vell.com, Igor Mitsyanko <imitsyanko@...ntenna.com>,
Sergey Matyukevich <geomatsi@...il.com>, Kalle Valo <kvalo@...nel.org>,
Sanjay R Mehta <sanju.mehta@....com>, Shyam Sundar S K
<Shyam-sundar.S-k@....com>, Jon Mason <jdmason@...zu.us>, Dave Jiang
<dave.jiang@...el.com>, Allen Hubbe <allenbh@...il.com>, Bjorn Helgaas
<bhelgaas@...gle.com>, Alex Williamson <alex.williamson@...hat.com>,
Juergen Gross <jgross@...e.com>, Stefano Stabellini
<sstabellini@...nel.org>, Oleksandr Tyshchenko
<oleksandr_tyshchenko@...m.com>, Jaroslav Kysela <perex@...ex.cz>, Takashi
Iwai <tiwai@...e.com>, Chen Ni <nichen@...as.ac.cn>, Mario Limonciello
<mario.limonciello@....com>, Ricky Wu <ricky_wu@...ltek.com>, Al Viro
<viro@...iv.linux.org.uk>, Breno Leitao <leitao@...ian.org>, Kevin Tian
<kevin.tian@...el.com>, Thomas Gleixner <tglx@...utronix.de>, Ilpo
Järvinen <ilpo.jarvinen@...ux.intel.com>, Andy
Shevchenko <andriy.shevchenko@...ux.intel.com>, Mostafa Saleh
<smostafa@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>, Yi Liu
<yi.l.liu@...el.com>, Christian Brauner <brauner@...nel.org>, Ankit Agrawal
<ankita@...dia.com>, Eric Auger <eric.auger@...hat.com>, Reinette Chatre
<reinette.chatre@...el.com>, Ye Bin <yebin10@...wei.com>, Marek
Marczykowski-Górecki <marmarek@...isiblethingslab.com>,
Pierre-Louis Bossart <pierre-louis.bossart@...ux.dev>, Peter Ujfalusi
<peter.ujfalusi@...ux.intel.com>, Maarten Lankhorst
<maarten.lankhorst@...ux.intel.com>, Kai Vehmanen
<kai.vehmanen@...ux.intel.com>, Rui Salvaterra <rsalvaterra@...il.com>,
linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-input@...r.kernel.org, netdev@...r.kernel.org,
linux-wireless@...r.kernel.org, ntb@...ts.linux.dev,
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xen-devel@...ts.xenproject.org, linux-sound@...r.kernel.org
Subject: Re: [PATCH 02/13] ALSA: hda_intel: Use always-managed version of pcim_intx()
On Wed, 23 Oct 2024 15:50:09 +0200,
Philipp Stanner wrote:
>
> On Tue, 2024-10-22 at 16:08 +0200, Takashi Iwai wrote:
> > On Tue, 15 Oct 2024 20:51:12 +0200,
> > Philipp Stanner wrote:
> > >
> > > 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 <pstanner@...hat.com>
> > > ---
> > > 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.
>
> >
> > 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.
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.
That said, I thought of something like below.
thanks,
Takashi
-- 8< --
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -438,8 +438,17 @@ static void pcim_intx_restore(struct device *dev, void *data)
__pcim_intx(pdev, res->orig_intx);
}
-static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
+static void save_orig_intx(struct pci_dev *pdev)
{
+ u16 pci_command;
+
+ pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+ res->orig_intx = !(pci_command & PCI_COMMAND_INTX_DISABLE);
+}
+
+static struct pcim_intx_devres *get_or_create_intx_devres(struct pci_dev *pdev)
+{
+ struct device *dev = &pdev->dev;
struct pcim_intx_devres *res;
res = devres_find(dev, pcim_intx_restore, NULL, NULL);
@@ -447,8 +456,10 @@ static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
return res;
res = devres_alloc(pcim_intx_restore, sizeof(*res), GFP_KERNEL);
- if (res)
+ if (res) {
+ save_orig_intx(pdev);
devres_add(dev, res);
+ }
return res;
}
@@ -467,11 +478,10 @@ int pcim_intx(struct pci_dev *pdev, int enable)
{
struct pcim_intx_devres *res;
- res = get_or_create_intx_devres(&pdev->dev);
+ res = get_or_create_intx_devres(pdev);
if (!res)
return -ENOMEM;
- res->orig_intx = !enable;
__pcim_intx(pdev, enable);
return 0;
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