Re: [PATCH V2] simplify init function

[Niklas Cassel <cassel@kernel.org>]

On Tue, Jan 14, 2025 at 10:03:44AM +0900, Damien Le Moal wrote:
> On 1/14/25 01:34, Tomas Henzl wrote:
> > by removing few lines. No functional change.
> 
> Looks OK to me, but:
> 
> The patch title should be: "ata: ahci: simplify init function"
> 
> And the commit message should also describe why it is OK to change
> ahci_init_irq() to be a void function. Can you send a V3 with that addressed
> please ?

I assume that this simplification is possible because sending in flags
(PCI_IRQ_MSIX | PCI_IRQ_INTX) to pci_alloc_irq_vectors() guarantees that
it will first try to allocate MSIX, if so, that should have be mentioned
in the commit message.



Also, you are just replacing pci_intx() with
pci_alloc_irq_vectors(.., PCI_IRQ_INTX), is this always safe?
If so, it should have been mentioned in the commit message.

pci_intx() is a hybrid function which can sometimes be managed through
devres. To remove this hybrid nature from pci_intx(), Philip has written
patches that ports users to either an always-managed or a never-managed
version.

A libata patch for this is currently queued via the PCI tree (pci/next),
see linux-next:
https://lore.kernel.org/linux-ide/Z1vFWyHkBD4d5xnG@ryzen/T/#mc20794f1e8712dafe77bc64c8da44c4d9b227b28
https://lore.kernel.org/linux-ide/Z1vFWyHkBD4d5xnG@ryzen/T/#m3a42ac564d97d10f8b1924c675efd144c845f8d5

Your patch conflicts with his series, which is already queued.


Kind regards,
Niklas


> 
> > 
> > Signed-off-by: Tomas Henzl <thenzl@redhat.com>
> > ---
> > V2: ahci_init_irq is now a void function
> > 
> >  drivers/ata/ahci.c | 23 ++++++++++++-----------
> >  1 file changed, 12 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> > index 8d27c567be1c..3ea2f3adf354 100644
> > --- a/drivers/ata/ahci.c
> > +++ b/drivers/ata/ahci.c
> > @@ -1665,13 +1665,15 @@ static int ahci_get_irq_vector(struct ata_host *host, int port)
> >  	return pci_irq_vector(to_pci_dev(host->dev), port);
> >  }
> >  
> > -static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
> > +static void ahci_init_irq(struct pci_dev *pdev, unsigned int n_ports,
> >  			struct ahci_host_priv *hpriv)
> >  {
> >  	int nvec;
> >  
> > -	if (hpriv->flags & AHCI_HFLAG_NO_MSI)
> > -		return -ENODEV;
> > +	if (hpriv->flags & AHCI_HFLAG_NO_MSI) {
> > +		pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_INTX);
> > +		return;
> > +	}
> >  
> >  	/*
> >  	 * If number of MSIs is less than number of ports then Sharing Last
> > @@ -1685,7 +1687,7 @@ static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
> >  			if (!(readl(hpriv->mmio + HOST_CTL) & HOST_MRSM)) {
> >  				hpriv->get_irq_vector = ahci_get_irq_vector;
> >  				hpriv->flags |= AHCI_HFLAG_MULTI_MSI;
> > -				return nvec;
> > +				return;
> >  			}
> >  
> >  			/*
> > @@ -1700,12 +1702,13 @@ static int ahci_init_msi(struct pci_dev *pdev, unsigned int n_ports,
> >  
> >  	/*
> >  	 * If the host is not capable of supporting per-port vectors, fall
> > -	 * back to single MSI before finally attempting single MSI-X.
> > +	 * back to single MSI before finally attempting single MSI-X or
> > +	 * a legacy INTx.
> >  	 */
> >  	nvec = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> >  	if (nvec == 1)
> > -		return nvec;
> > -	return pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSIX);
> > +		return;
> > +	pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSIX | PCI_IRQ_INTX);
> >  }
> >  
> >  static void ahci_mark_external_port(struct ata_port *ap)
> > @@ -1985,10 +1988,8 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  	}
> >  	host->private_data = hpriv;
> >  
> > -	if (ahci_init_msi(pdev, n_ports, hpriv) < 0) {
> > -		/* legacy intx interrupts */
> > -		pci_intx(pdev, 1);
> > -	}
> > +	ahci_init_irq(pdev, n_ports, hpriv);
> > +
> >  	hpriv->irq = pci_irq_vector(pdev, 0);
> >  
> >  	if (!(hpriv->cap & HOST_CAP_SSS) || ahci_ignore_sss)
> 
> 
> -- 
> Damien Le Moal
> Western Digital Research