On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <[email protected]> wrote:
>
> On some platforms, the ACPI _PRT function returns duplicate interrupt
> routing entries. Linux uses the first matching entry, but sometimes the
> second matching entry contains the correct interrupt vector.
>
> As a debugging aid, print a warning to dmesg if duplicate interrupt
> routing entries are present. This way, we could check how many models
> are affected.
>
> This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel
> SMBus controller. This controller is nonfunctional unless its interrupt
> usage is disabled (using the "disable_features=0x10" module parameter).
>
> After investigation, it turned out that the driver was using an
> incorrect interrupt vector: in lspci output for this device there was:
> Interrupt: pin B routed to IRQ 19
> but after running i2cdetect (without using any i2c-i801 module
> parameters) the following was logged to dmesg:
>
> [...]
> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> i801_smbus 0000:00:1f.3: Transaction timeout
> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> i801_smbus 0000:00:1f.3: Transaction timeout
> irq 17: nobody cared (try booting with the "irqpoll" option)
>
> Existence of duplicate entries in a table returned by the _PRT method
> was confirmed by disassembling the ACPI DSDT table.
>
> Windows XP is using IRQ3 (as reported by HWiNFO32 and in the Device
> Manager), which is neither of the two vectors returned by _PRT.
> As HWiNFO32 decoded contents of the SPD EEPROMs, the i2c-i801 device is
> working under Windows. It appears that Windows has reconfigured the
> chipset independently to use another interrupt vector for the device.
> This is possible, according to the chipset datasheet [1], page 436 for
> example (PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control Register).
>
> [1] https://www.intel.com/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf
>
> Signed-off-by: Mateusz Jończyk <[email protected]>
> Cc: Bjorn Helgaas <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Len Brown <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Jean Delvare <[email protected]>
> Previously-reviewed-by: Jean Delvare <[email protected]>
> Previously-tested-by: Jean Delvare <[email protected]>
>
> ---
> Hello,
>
> I'm resurrecting an older patch that was discussed back in January:
>
> https://lore.kernel.org/lkml/[email protected]/T/#u
>
> To consider: should we print a warning or an error in case of duplicate
> entries? This may not be serious enough to disturb the user with an
> error message at boot.
>
> I'm also looking into modifying the i2c-i801 driver to disable its usage
> of interrupts if one did not fire.
>
> v2: - add a newline at the end of the kernel log message,
> - replace: "if (match == NULL)" -> "if (!match)"
> - patch description tweaks.
> v3: - fix C style issues pointed by Jean Delvare,
> - switch severity from warning to error.
> v3 RESEND: retested on top of v6.2-rc4
> v4: - rebase and retest on top of v6.7-rc7
> - switch severity back to warning,
> - change pr_err() to dev_warn() and simplify the code,
> - modify patch description (describe Windows behaviour etc.)
> ---
> drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++---
> 1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
> index ff30ceca2203..1fcf72e335b0 100644
> --- a/drivers/acpi/pci_irq.c
> +++ b/drivers/acpi/pci_irq.c
> @@ -203,6 +203,8 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
> struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> struct acpi_pci_routing_table *entry;
> acpi_handle handle = NULL;
> + struct acpi_prt_entry *match = NULL;
> + const char *match_int_source = NULL;
>
> if (dev->bus->bridge)
> handle = ACPI_HANDLE(dev->bus->bridge);
> @@ -219,13 +221,30 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
>
> entry = buffer.pointer;
> while (entry && (entry->length > 0)) {
> - if (!acpi_pci_irq_check_entry(handle, dev, pin,
> - entry, entry_ptr))
> - break;
> + struct acpi_prt_entry *curr;
> +
> + if (!acpi_pci_irq_check_entry(handle, dev, pin, entry, &curr)) {
> + if (!match) {
> + match = curr;
> + match_int_source = entry->source;
> + } else {
> + dev_warn(&dev->dev, FW_BUG
dev_info() would be sufficient here IMV.
> + "ACPI _PRT returned duplicate IRQ routing entries for INT%c: %s[%d] and %s[%d]\n",
> + pin_name(curr->pin),
> + match_int_source, match->index,
> + entry->source, curr->index);
> + /* We use the first matching entry nonetheless,
> + * for compatibility with older kernels.
> + */
> + }
> + }
> +
> entry = (struct acpi_pci_routing_table *)
> ((unsigned long)entry + entry->length);
> }
>
> + *entry_ptr = match;
> +
> kfree(buffer.pointer);
> return 0;
> }
>
> base-commit: 861deac3b092f37b2c5e6871732f3e11486f7082
> --
Bjorn, any concerns regarding this one?
On Fri, Feb 16, 2024 at 07:26:06PM +0100, Rafael J. Wysocki wrote:
> On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <[email protected]> wrote:
> >
> > On some platforms, the ACPI _PRT function returns duplicate interrupt
> > routing entries. Linux uses the first matching entry, but sometimes the
> > second matching entry contains the correct interrupt vector.
> >
> > As a debugging aid, print a warning to dmesg if duplicate interrupt
> > routing entries are present. This way, we could check how many models
> > are affected.
> >
> > This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel
> > SMBus controller. This controller is nonfunctional unless its interrupt
> > usage is disabled (using the "disable_features=0x10" module parameter).
> >
> > After investigation, it turned out that the driver was using an
> > incorrect interrupt vector: in lspci output for this device there was:
> > Interrupt: pin B routed to IRQ 19
> > but after running i2cdetect (without using any i2c-i801 module
> > parameters) the following was logged to dmesg:
> >
> > [...]
> > i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> > i801_smbus 0000:00:1f.3: Transaction timeout
> > i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> > i801_smbus 0000:00:1f.3: Transaction timeout
> > irq 17: nobody cared (try booting with the "irqpoll" option)
> >
> > Existence of duplicate entries in a table returned by the _PRT method
> > was confirmed by disassembling the ACPI DSDT table.
> >
> > Windows XP is using IRQ3 (as reported by HWiNFO32 and in the Device
> > Manager), which is neither of the two vectors returned by _PRT.
> > As HWiNFO32 decoded contents of the SPD EEPROMs, the i2c-i801 device is
> > working under Windows. It appears that Windows has reconfigured the
> > chipset independently to use another interrupt vector for the device.
> > This is possible, according to the chipset datasheet [1], page 436 for
> > example (PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control Register).
> >
> > [1] https://www.intel.com/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf
> >
> > Signed-off-by: Mateusz Jończyk <[email protected]>
> > Cc: Bjorn Helgaas <[email protected]>
> > Cc: "Rafael J. Wysocki" <[email protected]>
> > Cc: Len Brown <[email protected]>
> > Cc: Borislav Petkov <[email protected]>
> > Cc: Jean Delvare <[email protected]>
> > Previously-reviewed-by: Jean Delvare <[email protected]>
> > Previously-tested-by: Jean Delvare <[email protected]>
> >
> > ---
> > Hello,
> >
> > I'm resurrecting an older patch that was discussed back in January:
> >
> > https://lore.kernel.org/lkml/[email protected]/T/#u
> >
> > To consider: should we print a warning or an error in case of duplicate
> > entries? This may not be serious enough to disturb the user with an
> > error message at boot.
> >
> > I'm also looking into modifying the i2c-i801 driver to disable its usage
> > of interrupts if one did not fire.
> >
> > v2: - add a newline at the end of the kernel log message,
> > - replace: "if (match == NULL)" -> "if (!match)"
> > - patch description tweaks.
> > v3: - fix C style issues pointed by Jean Delvare,
> > - switch severity from warning to error.
> > v3 RESEND: retested on top of v6.2-rc4
> > v4: - rebase and retest on top of v6.7-rc7
> > - switch severity back to warning,
> > - change pr_err() to dev_warn() and simplify the code,
> > - modify patch description (describe Windows behaviour etc.)
> > ---
> > drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++---
> > 1 file changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
> > index ff30ceca2203..1fcf72e335b0 100644
> > --- a/drivers/acpi/pci_irq.c
> > +++ b/drivers/acpi/pci_irq.c
> > @@ -203,6 +203,8 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
> > struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> > struct acpi_pci_routing_table *entry;
> > acpi_handle handle = NULL;
> > + struct acpi_prt_entry *match = NULL;
> > + const char *match_int_source = NULL;
> >
> > if (dev->bus->bridge)
> > handle = ACPI_HANDLE(dev->bus->bridge);
> > @@ -219,13 +221,30 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
> >
> > entry = buffer.pointer;
> > while (entry && (entry->length > 0)) {
> > - if (!acpi_pci_irq_check_entry(handle, dev, pin,
> > - entry, entry_ptr))
> > - break;
> > + struct acpi_prt_entry *curr;
> > +
> > + if (!acpi_pci_irq_check_entry(handle, dev, pin, entry, &curr)) {
> > + if (!match) {
> > + match = curr;
> > + match_int_source = entry->source;
> > + } else {
> > + dev_warn(&dev->dev, FW_BUG
>
> dev_info() would be sufficient here IMV.
>
> > + "ACPI _PRT returned duplicate IRQ routing entries for INT%c: %s[%d] and %s[%d]\n",
> > + pin_name(curr->pin),
> > + match_int_source, match->index,
> > + entry->source, curr->index);
> > + /* We use the first matching entry nonetheless,
> > + * for compatibility with older kernels.
The usual comment style in this file is:
/*
* We use ...
*/
> > + */
> > + }
> > + }
> > +
> > entry = (struct acpi_pci_routing_table *)
> > ((unsigned long)entry + entry->length);
> > }
> >
> > + *entry_ptr = match;
> > +
> > kfree(buffer.pointer);
> > return 0;
> > }
> >
> > base-commit: 861deac3b092f37b2c5e6871732f3e11486f7082
> > --
>
> Bjorn, any concerns regarding this one?
No concerns from me.
I guess this only adds a message, right? It doesn't actually fix
anything or change any behavior?
This talks about "duplicate" entries, which suggests to me that they
are identical, but I don't think they are. It sounds like it's two
"matching" entries, i.e., two entries for the same (device, pin)?
And neither of the two _PRT entries yields a working i801 device?
Bjorn
W dniu 16.02.2024 o 19:49, Bjorn Helgaas pisze:
> On Fri, Feb 16, 2024 at 07:26:06PM +0100, Rafael J. Wysocki wrote:
>> On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <[email protected]> wrote:
>>> On some platforms, the ACPI _PRT function returns duplicate interrupt
>>> routing entries. Linux uses the first matching entry, but sometimes the
>>> second matching entry contains the correct interrupt vector.
>>>
>>> As a debugging aid, print a warning to dmesg if duplicate interrupt
>>> routing entries are present. This way, we could check how many models
>>> are affected.
>>>
>>> This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel
>>> SMBus controller. This controller is nonfunctional unless its interrupt
>>> usage is disabled (using the "disable_features=0x10" module parameter).
>>>
>>> After investigation, it turned out that the driver was using an
>>> incorrect interrupt vector: in lspci output for this device there was:
>>> Interrupt: pin B routed to IRQ 19
>>> but after running i2cdetect (without using any i2c-i801 module
>>> parameters) the following was logged to dmesg:
>>>
>>> [...]
>>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
>>> i801_smbus 0000:00:1f.3: Transaction timeout
>>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
>>> i801_smbus 0000:00:1f.3: Transaction timeout
>>> irq 17: nobody cared (try booting with the "irqpoll" option)
>>>
>>> Existence of duplicate entries in a table returned by the _PRT method
>>> was confirmed by disassembling the ACPI DSDT table.
>>>
>>> Windows XP is using IRQ3 (as reported by HWiNFO32 and in the Device
>>> Manager), which is neither of the two vectors returned by _PRT.
>>> As HWiNFO32 decoded contents of the SPD EEPROMs, the i2c-i801 device is
>>> working under Windows. It appears that Windows has reconfigured the
>>> chipset independently to use another interrupt vector for the device.
>>> This is possible, according to the chipset datasheet [1], page 436 for
>>> example (PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control Register).
>>>
>>> [1] https://www.intel.com/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf
>>>
>>> Signed-off-by: Mateusz Jończyk <[email protected]>
>>> Cc: Bjorn Helgaas <[email protected]>
>>> Cc: "Rafael J. Wysocki" <[email protected]>
>>> Cc: Len Brown <[email protected]>
>>> Cc: Borislav Petkov <[email protected]>
>>> Cc: Jean Delvare <[email protected]>
>>> Previously-reviewed-by: Jean Delvare <[email protected]>
>>> Previously-tested-by: Jean Delvare <[email protected]>
>>>
>>> ---
>>> Hello,
>>>
>>> I'm resurrecting an older patch that was discussed back in January:
>>>
>>> https://lore.kernel.org/lkml/[email protected]/T/#u
>>>
>>> To consider: should we print a warning or an error in case of duplicate
>>> entries? This may not be serious enough to disturb the user with an
>>> error message at boot.
>>>
>>> I'm also looking into modifying the i2c-i801 driver to disable its usage
>>> of interrupts if one did not fire.
>>>
>>> v2: - add a newline at the end of the kernel log message,
>>> - replace: "if (match == NULL)" -> "if (!match)"
>>> - patch description tweaks.
>>> v3: - fix C style issues pointed by Jean Delvare,
>>> - switch severity from warning to error.
>>> v3 RESEND: retested on top of v6.2-rc4
>>> v4: - rebase and retest on top of v6.7-rc7
>>> - switch severity back to warning,
>>> - change pr_err() to dev_warn() and simplify the code,
>>> - modify patch description (describe Windows behaviour etc.)
>>> ---
>>> drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++---
>>> 1 file changed, 22 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
>>> index ff30ceca2203..1fcf72e335b0 100644
>>> --- a/drivers/acpi/pci_irq.c
>>> +++ b/drivers/acpi/pci_irq.c
>>> @@ -203,6 +203,8 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
>>> struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>>> struct acpi_pci_routing_table *entry;
>>> acpi_handle handle = NULL;
>>> + struct acpi_prt_entry *match = NULL;
>>> + const char *match_int_source = NULL;
>>>
>>> if (dev->bus->bridge)
>>> handle = ACPI_HANDLE(dev->bus->bridge);
>>> @@ -219,13 +221,30 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
>>>
>>> entry = buffer.pointer;
>>> while (entry && (entry->length > 0)) {
>>> - if (!acpi_pci_irq_check_entry(handle, dev, pin,
>>> - entry, entry_ptr))
>>> - break;
>>> + struct acpi_prt_entry *curr;
>>> +
>>> + if (!acpi_pci_irq_check_entry(handle, dev, pin, entry, &curr)) {
>>> + if (!match) {
>>> + match = curr;
>>> + match_int_source = entry->source;
>>> + } else {
>>> + dev_warn(&dev->dev, FW_BUG
>> dev_info() would be sufficient here IMV.
>>
>>> + "ACPI _PRT returned duplicate IRQ routing entries for INT%c: %s[%d] and %s[%d]\n",
>>> + pin_name(curr->pin),
>>> + match_int_source, match->index,
>>> + entry->source, curr->index);
>>> + /* We use the first matching entry nonetheless,
>>> + * for compatibility with older kernels.
> The usual comment style in this file is:
>
> /*
> * We use ...
> */
>
>>> + */
>>> + }
>>> + }
>>> +
>>> entry = (struct acpi_pci_routing_table *)
>>> ((unsigned long)entry + entry->length);
>>> }
>>>
>>> + *entry_ptr = match;
>>> +
>>> kfree(buffer.pointer);
>>> return 0;
>>> }
>>>
>>> base-commit: 861deac3b092f37b2c5e6871732f3e11486f7082
>>> --
>> Bjorn, any concerns regarding this one?
> No concerns from me.
>
> I guess this only adds a message, right? It doesn't actually fix
> anything or change any behavior?
Exactly.
> This talks about "duplicate" entries, which suggests to me that they
> are identical, but I don't think they are. It sounds like it's two
> "matching" entries, i.e., two entries for the same (device, pin)?
Right.
> And neither of the two _PRT entries yields a working i801 device?
Unpatched Linux uses the first matching entry, but the second one gives
a working i801 device. The point is to print a warning message to see
how many devices are affected and whether it is safe to switch the code
to use the last matching entry in all instances.
Therefore I used dev_warn().
> Bjorn
Greetings,
Mateusz
On Fri, Feb 16, 2024 at 9:20 PM Mateusz Jończyk <[email protected]> wrote:
>
> W dniu 16.02.2024 o 19:49, Bjorn Helgaas pisze:
> > On Fri, Feb 16, 2024 at 07:26:06PM +0100, Rafael J. Wysocki wrote:
> >> On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <[email protected]> wrote:
> >>> On some platforms, the ACPI _PRT function returns duplicate interrupt
> >>> routing entries. Linux uses the first matching entry, but sometimes the
> >>> second matching entry contains the correct interrupt vector.
> >>>
> >>> As a debugging aid, print a warning to dmesg if duplicate interrupt
> >>> routing entries are present. This way, we could check how many models
> >>> are affected.
> >>>
> >>> This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel
> >>> SMBus controller. This controller is nonfunctional unless its interrupt
> >>> usage is disabled (using the "disable_features=0x10" module parameter).
> >>>
> >>> After investigation, it turned out that the driver was using an
> >>> incorrect interrupt vector: in lspci output for this device there was:
> >>> Interrupt: pin B routed to IRQ 19
> >>> but after running i2cdetect (without using any i2c-i801 module
> >>> parameters) the following was logged to dmesg:
> >>>
> >>> [...]
> >>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> >>> i801_smbus 0000:00:1f.3: Transaction timeout
> >>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
> >>> i801_smbus 0000:00:1f.3: Transaction timeout
> >>> irq 17: nobody cared (try booting with the "irqpoll" option)
> >>>
> >>> Existence of duplicate entries in a table returned by the _PRT method
> >>> was confirmed by disassembling the ACPI DSDT table.
> >>>
> >>> Windows XP is using IRQ3 (as reported by HWiNFO32 and in the Device
> >>> Manager), which is neither of the two vectors returned by _PRT.
> >>> As HWiNFO32 decoded contents of the SPD EEPROMs, the i2c-i801 device is
> >>> working under Windows. It appears that Windows has reconfigured the
> >>> chipset independently to use another interrupt vector for the device.
> >>> This is possible, according to the chipset datasheet [1], page 436 for
> >>> example (PIRQ[n]_ROUT—PIRQ[A,B,C,D] Routing Control Register).
> >>>
> >>> [1] https://www.intel.com/content/dam/doc/datasheet/io-controller-hub-9-datasheet.pdf
> >>>
> >>> Signed-off-by: Mateusz Jończyk <[email protected]>
> >>> Cc: Bjorn Helgaas <[email protected]>
> >>> Cc: "Rafael J. Wysocki" <[email protected]>
> >>> Cc: Len Brown <[email protected]>
> >>> Cc: Borislav Petkov <[email protected]>
> >>> Cc: Jean Delvare <[email protected]>
> >>> Previously-reviewed-by: Jean Delvare <[email protected]>
> >>> Previously-tested-by: Jean Delvare <[email protected]>
> >>>
> >>> ---
> >>> Hello,
> >>>
> >>> I'm resurrecting an older patch that was discussed back in January:
> >>>
> >>> https://lore.kernel.org/lkml/[email protected]/T/#u
> >>>
> >>> To consider: should we print a warning or an error in case of duplicate
> >>> entries? This may not be serious enough to disturb the user with an
> >>> error message at boot.
> >>>
> >>> I'm also looking into modifying the i2c-i801 driver to disable its usage
> >>> of interrupts if one did not fire.
> >>>
> >>> v2: - add a newline at the end of the kernel log message,
> >>> - replace: "if (match == NULL)" -> "if (!match)"
> >>> - patch description tweaks.
> >>> v3: - fix C style issues pointed by Jean Delvare,
> >>> - switch severity from warning to error.
> >>> v3 RESEND: retested on top of v6.2-rc4
> >>> v4: - rebase and retest on top of v6.7-rc7
> >>> - switch severity back to warning,
> >>> - change pr_err() to dev_warn() and simplify the code,
> >>> - modify patch description (describe Windows behaviour etc.)
> >>> ---
> >>> drivers/acpi/pci_irq.c | 25 ++++++++++++++++++++++---
> >>> 1 file changed, 22 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
> >>> index ff30ceca2203..1fcf72e335b0 100644
> >>> --- a/drivers/acpi/pci_irq.c
> >>> +++ b/drivers/acpi/pci_irq.c
> >>> @@ -203,6 +203,8 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
> >>> struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> >>> struct acpi_pci_routing_table *entry;
> >>> acpi_handle handle = NULL;
> >>> + struct acpi_prt_entry *match = NULL;
> >>> + const char *match_int_source = NULL;
> >>>
> >>> if (dev->bus->bridge)
> >>> handle = ACPI_HANDLE(dev->bus->bridge);
> >>> @@ -219,13 +221,30 @@ static int acpi_pci_irq_find_prt_entry(struct pci_dev *dev,
> >>>
> >>> entry = buffer.pointer;
> >>> while (entry && (entry->length > 0)) {
> >>> - if (!acpi_pci_irq_check_entry(handle, dev, pin,
> >>> - entry, entry_ptr))
> >>> - break;
> >>> + struct acpi_prt_entry *curr;
> >>> +
> >>> + if (!acpi_pci_irq_check_entry(handle, dev, pin, entry, &curr)) {
> >>> + if (!match) {
> >>> + match = curr;
> >>> + match_int_source = entry->source;
> >>> + } else {
> >>> + dev_warn(&dev->dev, FW_BUG
> >> dev_info() would be sufficient here IMV.
> >>
> >>> + "ACPI _PRT returned duplicate IRQ routing entries for INT%c: %s[%d] and %s[%d]\n",
> >>> + pin_name(curr->pin),
> >>> + match_int_source, match->index,
> >>> + entry->source, curr->index);
> >>> + /* We use the first matching entry nonetheless,
> >>> + * for compatibility with older kernels.
> > The usual comment style in this file is:
> >
> > /*
> > * We use ...
> > */
> >
> >>> + */
> >>> + }
> >>> + }
> >>> +
> >>> entry = (struct acpi_pci_routing_table *)
> >>> ((unsigned long)entry + entry->length);
> >>> }
> >>>
> >>> + *entry_ptr = match;
> >>> +
> >>> kfree(buffer.pointer);
> >>> return 0;
> >>> }
> >>>
> >>> base-commit: 861deac3b092f37b2c5e6871732f3e11486f7082
> >>> --
> >> Bjorn, any concerns regarding this one?
> > No concerns from me.
> >
> > I guess this only adds a message, right? It doesn't actually fix
> > anything or change any behavior?
> Exactly.
> > This talks about "duplicate" entries, which suggests to me that they
> > are identical, but I don't think they are. It sounds like it's two
> > "matching" entries, i.e., two entries for the same (device, pin)?
>
> Right.
>
> > And neither of the two _PRT entries yields a working i801 device?
>
> Unpatched Linux uses the first matching entry, but the second one gives
> a working i801 device. The point is to print a warning message to see
> how many devices are affected and whether it is safe to switch the code
> to use the last matching entry in all instances.
>
> Therefore I used dev_warn().
I don't quite see a connection between the above and the log level.
W dniu 16.02.2024 o 21:51, Rafael J. Wysocki pisze:
> On Fri, Feb 16, 2024 at 9:20 PM Mateusz Jończyk <[email protected]> wrote:
>> W dniu 16.02.2024 o 19:49, Bjorn Helgaas pisze:
>>> On Fri, Feb 16, 2024 at 07:26:06PM +0100, Rafael J. Wysocki wrote:
>>>> On Tue, Dec 26, 2023 at 1:50 PM Mateusz Jończyk <[email protected]> wrote:
>>>>> On some platforms, the ACPI _PRT function returns duplicate interrupt
>>>>> routing entries. Linux uses the first matching entry, but sometimes the
>>>>> second matching entry contains the correct interrupt vector.
>>>>>
>>>>> As a debugging aid, print a warning to dmesg if duplicate interrupt
>>>>> routing entries are present. This way, we could check how many models
>>>>> are affected.
>>>>>
>>>>> This happens on a Dell Latitude E6500 laptop with the i2c-i801 Intel
>>>>> SMBus controller. This controller is nonfunctional unless its interrupt
>>>>> usage is disabled (using the "disable_features=0x10" module parameter).
>>>>>
>>>>> After investigation, it turned out that the driver was using an
>>>>> incorrect interrupt vector: in lspci output for this device there was:
>>>>> Interrupt: pin B routed to IRQ 19
>>>>> but after running i2cdetect (without using any i2c-i801 module
>>>>> parameters) the following was logged to dmesg:
>>>>>
>>>>> [...]
>>>>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
>>>>> i801_smbus 0000:00:1f.3: Transaction timeout
>>>>> i801_smbus 0000:00:1f.3: Timeout waiting for interrupt!
>>>>> i801_smbus 0000:00:1f.3: Transaction timeout
>>>>> irq 17: nobody cared (try booting with the "irqpoll" option)
>>>>>
>>>>> Existence of duplicate entries in a table returned by the _PRT method
>>>>> was confirmed by disassembling the ACPI DSDT table.
[snip]
>>> And neither of the two _PRT entries yields a working i801 device?
>> Unpatched Linux uses the first matching entry, but the second one gives
>> a working i801 device. The point is to print a warning message to see
>> how many devices are affected and whether it is safe to switch the code
>> to use the last matching entry in all instances.
>>
>> Therefore I used dev_warn().
> I don't quite see a connection between the above and the log level.
OK, so I'll use dev_info() then.
Greetings,
Mateusz