Re: [PATCH 2/5] ata: libahci_platform: Support per-port interrupts

From: Marc Zyngier <marc.zyngier@arm.com>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org, Jason Cooper <jason@lakedaemon.net>,
	Andrew Lunn <andrew@lunn.ch>,
	Antoine Tenart <antoine.tenart@bootlin.com>,
	Gregory Clement <gregory.clement@bootlin.com>,
	Maxime Chevallier <maxime.chevallier@bootlin.com>,
	Nadav Haklai <nadavh@marvell.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Rob Herring <robh+dt@kernel.org>, Jens Axboe <axboe@kernel.dk>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	linux-ide@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	linux-arm-kernel@lists.infradead.org,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH 2/5] ata: libahci_platform: Support per-port interrupts
Date: Fri, 22 Feb 2019 16:41:48 +0000	[thread overview]
Message-ID: <86pnrjrd0z.wl-marc.zyngier@arm.com> (raw)
In-Reply-To: <20190222170348.12e45f42@xps13>

On Fri, 22 Feb 2019 16:03:48 +0000,
Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> Hi Hans,
> 
> Hans de Goede <hdegoede@redhat.com> wrote on Fri, 22 Feb 2019 16:52:55
> +0100:
> 
> > Hi,
> > 
> > On 2/22/19 4:31 PM, Miquel Raynal wrote:
> > > Hi Hans,
> > > 
> > > Hans de Goede <hdegoede@redhat.com> wrote on Fri, 22 Feb 2019 16:26:01
> > > +0100:
> > >   
> > >> Hi,
> > >>
> > >> On 2/22/19 3:53 PM, Miquel Raynal wrote:  
> > >>> Right now the ATA core only allows IPs to use a single interrupt. Some
> > >>> of them (for instance the Armada-CP110 one) actually has one interrupt
> > >>> per port. Add some logic to support such situation.
> > >>>
> > >>> We consider that either there is one single interrupt declared in the
> > >>> main IP node, or there are per-port interrupts, each of them being
> > >>> declared in the port sub-nodes.
> > >>>
> > >>> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > >>> ---
> > >>>    drivers/ata/acard-ahci.c       |  2 +-
> > >>>    drivers/ata/ahci.c             |  2 +-
> > >>>    drivers/ata/ahci.h             |  3 +-
> > >>>    drivers/ata/libahci.c          |  2 +-
> > >>>    drivers/ata/libahci_platform.c | 66 ++++++++++++++++++++++++++++------
> > >>>    drivers/ata/sata_highbank.c    |  2 +-
> > >>>    6 files changed, 61 insertions(+), 16 deletions(-)
> > >>>
> > >>> diff --git a/drivers/ata/acard-ahci.c b/drivers/ata/acard-ahci.c
> > >>> index 583e366be7e2..9414b81e994c 100644
> > >>> --- a/drivers/ata/acard-ahci.c
> > >>> +++ b/drivers/ata/acard-ahci.c
> > >>> @@ -434,7 +434,7 @@ static int acard_ahci_init_one(struct pci_dev *pdev, const struct pci_device_id
> > >>>    	if (!hpriv)
> > >>>    		return -ENOMEM;  
> > >>>    > -	hpriv->irq = pdev->irq;  
> > >>> +	hpriv->irqs[0] = pdev->irq;
> > >>>    	hpriv->flags |= (unsigned long)pi.private_data;  
> > >>>      >> What code-path is going to alloc hpriv->irqs for drivers using this code-path  
> > >> which are not using libahci_platform .c ?  
> > > 
> > > I don't understand the question (or the remark behind the question),
> > > can you explain a little bit more what you have in mind?  
> > 
> > Sorry I got the code context wrong I meant to put that comment below this chunk:
> > 
> >  > diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
> >  > index 021ce46e2e57..18bce556d85f 100644
> >  > --- a/drivers/ata/ahci.c
> >  > +++ b/drivers/ata/ahci.c
> >  > @@ -1817,7 +1817,7 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  >   		/* legacy intx interrupts */
> >  >   		pci_intx(pdev, 1);
> >  >   	}
> >  > -	hpriv->irq = pci_irq_vector(pdev, 0);
> >  > +	hpriv->irqs[0] = pci_irq_vector(pdev, 0);
> >  >
> >  >   	if (!(hpriv->cap & HOST_CAP_SSS) || ahci_ignore_sss)
> >  >   		host->flags |= ATA_HOST_PARALLEL_SCAN;  
> > 
> > 
> > Which AFAIK is a common code-path also used by ahci drivers not using
> > libahci_platform, and in that case hpriv->irqs will be NULL as nothing
> > initializes it.
> 
> Oh I see. What do you prefer:
> 1/
> * I add "irqs" besides "irq" in the structure
> * copy the value of irq in irqs[0]
> * use irqs instead of irq in the libahci_platform ?
> or
> 2/
> * Allocated one irq there if there is none ?

3) you make it a union, and only use it as a pointer when some flag
somewhere says that you have multiple interrupts.

Yes, this is terrible, but it would limit the changes to the one
affected platform instead of inflicting the changes on all SATA users.

	M.

-- 
Jazz is not dead, it just smell funny.