linux-kernel - Re: [PATCH v1 1/1] mfd: intel-lpss: Switch over to MSI interrupts

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Date: Mon, 25 Mar 2024 16:19:15 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Lee Jones <lee@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/1] mfd: intel-lpss: Switch over to MSI interrupts

[+bcc Mateusz]

On Tue, Mar 12, 2024 at 06:59:05PM +0200, Andy Shevchenko wrote:
> Some devices support MSI interrupts. Let's at least try to use them in
> platforms that provide MSI capability.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/mfd/intel-lpss-pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/intel-lpss-pci.c b/drivers/mfd/intel-lpss-pci.c
> index 8c00e0c695c5..c36a101df7be 100644
> --- a/drivers/mfd/intel-lpss-pci.c
> +++ b/drivers/mfd/intel-lpss-pci.c
> @@ -54,7 +54,7 @@ static int intel_lpss_pci_probe(struct pci_dev *pdev,
>  	if (ret)
>  		return ret;
>  
> -	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_LEGACY);
> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
>  	if (ret < 0)
>  		return ret;

I guess at least some of these devices do support INTx, since we
always used INTx previously, right?

There are a bunch of bug reports complaining about a lack of _PRT
entries for them, e.g., these from
https://bugzilla.kernel.org/show_bug.cgi?id=212261#c24:

  intel-lpss 0000:00:15.0: enabling device (0004 -> 0006)
  intel-lpss 0000:00:15.0: can't derive routing for PCI INT A
  intel-lpss 0000:00:15.0: PCI INT A: not connected
  intel-lpss: probe of 0000:00:15.0 failed with error -22
  intel-lpss 0000:00:15.2: enabling device (0004 -> 0006)
  intel-lpss 0000:00:15.2: can't derive routing for PCI INT C
  intel-lpss 0000:00:15.2: PCI INT C: not connected
  intel-lpss: probe of 0000:00:15.2 failed with error -22
  intel-lpss 0000:00:19.0: enabling device (0004 -> 0006)
  intel-lpss 0000:00:19.0: can't derive routing for PCI INT A
  intel-lpss 0000:00:19.0: PCI INT A: not connected
  intel-lpss: probe of 0000:00:19.0 failed with error -22
  intel-lpss 0000:00:19.1: enabling device (0004 -> 0006)
  intel-lpss 0000:00:19.1: can't derive routing for PCI INT B
  intel-lpss 0000:00:19.1: PCI INT B: not connected
  intel-lpss: probe of 0000:00:19.1 failed with error -22
  intel-lpss 0000:00:1e.0: enabling device (0004 -> 0006)
  intel-lpss 0000:00:1e.0: can't derive routing for PCI INT A
  intel-lpss 0000:00:1e.0: PCI INT A: not connected
  intel-lpss: probe of 0000:00:1e.0 failed with error -22
  intel-lpss 0000:00:1e.3: enabling device (0004 -> 0006)
  intel-lpss 0000:00:1e.3: can't derive routing for PCI INT D
  intel-lpss 0000:00:1e.3: PCI INT D: not connected
  intel-lpss: probe of 0000:00:1e.3 failed with error -22

I don't know if these are a _PRT bug (I think if a device advertises a
non-zero Interrupt Pin, the _PRT should tell us how it is routed), or
possibly a device bug (advertises Interrupt Pin == INTA when it should
advertise "no INTx used"), or something else.

Bjorn