linux-kernel - Re: [PATCH v2 6/9] PCI: dwc: Add support to use non default msi_irq

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Date:   Fri, 8 Feb 2019 10:22:22 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Murali Karicheri <m-karicheri2@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 6/9] PCI: dwc: Add support to use non default
 msi_irq_chip

On Fri, Feb 08, 2019 at 10:16:59AM +0530, Kishon Vijay Abraham I wrote:
> Hi Lorenzo,
> 
> On 07/02/19 10:18 PM, Lorenzo Pieralisi wrote:
> > On Thu, Feb 07, 2019 at 04:39:21PM +0530, Kishon Vijay Abraham I wrote:
> >> Platforms using Designware IP uses dw_pci_msi_bottom_irq_chip for
> >> configuring the MSI controller logic within the Designware IP. However
> >> certain platforms like Keystone (K2G) which uses Desingware IP has
> >> it's own MSI controller logic. For handling such platforms,
> >> the irqchip ops uses msi_irq_ack, msi_set_irq, msi_clear_irq callback
> >> functions.
> >>
> >> Add support to use different msi_irq_chip with default as
> >> dw_pci_msi_bottom_irq_chip. This is in preparation to get rid off
> >> msi_irq_ack, msi_set_irq, msi_clear_irq and other Keystone specific
> >> dw_pcie_host_ops. This will also help to get rid of get_msi_addr and
> >> get_msi_data ops.
> >>
> >> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> >> ---
> >>  drivers/pci/controller/dwc/pcie-designware-host.c | 5 ++++-
> >>  drivers/pci/controller/dwc/pcie-designware.h      | 1 +
> >>  2 files changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> >> index 721d60a5d9e4..042de09b0451 100644
> >> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> >> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> >> @@ -245,7 +245,7 @@ static int dw_pcie_irq_domain_alloc(struct irq_domain *domain,
> >>  
> >>  	for (i = 0; i < nr_irqs; i++)
> >>  		irq_domain_set_info(domain, virq + i, bit + i,
> >> -				    &dw_pci_msi_bottom_irq_chip,
> >> +				    pp->msi_irq_chip,
> >>  				    pp, handle_edge_irq,
> >>  				    NULL, NULL);
> >>  
> >> @@ -277,6 +277,9 @@ int dw_pcie_allocate_domains(struct pcie_port *pp)
> >>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> >>  	struct fwnode_handle *fwnode = of_node_to_fwnode(pci->dev->of_node);
> >>  
> >> +	if (!pp->msi_irq_chip)
> >> +		pp->msi_irq_chip = &dw_pci_msi_bottom_irq_chip;
> > 
> > I think it is better to initialize pp->msi_irq_chip outside
> > dw_pcie_allocate_domains(), it makes things clearer.
> > 
> > In:
> > 
> > dw_pcie_host_init() for dwc
> > 
> > or
> > 
> > msi_host_init() for platforms with that hook implemented.
> > 
> > Is there any gotcha I am missing ?
> 
> I added here only to avoid breaking "git bisect". Next patch adds
> ks_pcie_msi_irq_chip in msi_host_init of keystone. However till then it has to
> use dw_pci_msi_bottom_irq_chip. Adding anywhere else in dw_pcie_host_init would
> mean msi_irq_chip is uninitialized for keystone.
> 
> Maybe I can add that in the commit log and move it to dw_pcie_host_init?

I do not think you need to mention that in the commit log but move the
initialization of pp->msi_irq_chip in dw_pcie_host_init() in the next
patch, yes.

It is correct to keep bisectability, I should have read ahead.

Lorenzo