From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Date: Wed, 11 Nov 2015 16:38:02 +0000 Subject: Re: [PATCH] PCI: pcie-rcar: Fix OF node passed to MSI irq domain Message-Id: <20151111163802.3a96080c@arm.com> List-Id: References: <1446542899-25137-1-git-send-email-phil.edworthy@renesas.com> <20151109161115.GA13870@ulmo.nvidia.com> <20151110155232.GA25368@ulmo.nvidia.com> In-Reply-To: <20151110155232.GA25368@ulmo.nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Thierry Reding Cc: Phil Edworthy , Bjorn Helgaas , Wolfram Sang , Geert Uytterhoeven , Simon Horman , "linux-pci@vger.kernel.org" , "linux-sh@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Ley Foon Tan , Jingoo Han On Tue, 10 Nov 2015 16:52:33 +0100 Thierry Reding wrote: > On Mon, Nov 09, 2015 at 06:01:49PM +0000, Phil Edworthy wrote: > > Hi Thierry, > > > > On 09 November 2015 17:24, Phil wrote: > > > On 09 November 2015 16:11, Thierry wrote: > > > > On Mon, Nov 09, 2015 at 03:20:24PM +0000, Phil Edworthy wrote: > > > > > cc'ing others (Tegra, Altera, Designware) who may have the same bug > > > > > > > > > > On 03 November 2015 09:28, Phil Edworthy wrote: > > > > > > The OF node passed to irq_domain_add_linear() should be a > > > > > > pointer to interrupt controller's device tree node, or NULL, > > > > > > but not the PCI controller's node. > > > > > > > > > > > > This fixes an oops in msi_domain_alloc_irqs() when it tries > > > > > > to call msi_check(). > > > > > > > > > > > > Signed-off-by: Phil Edworthy > > > > > > --- > > > > > > drivers/pci/host/pcie-rcar.c | 2 +- > > > > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c > > > > > > index 2377bf0..c6fa562 100644 > > > > > > --- a/drivers/pci/host/pcie-rcar.c > > > > > > +++ b/drivers/pci/host/pcie-rcar.c > > > > > > @@ -709,7 +709,7 @@ static int rcar_pcie_enable_msi(struct rcar_pcie > > > *pcie) > > > > > > msi->chip.setup_irq = rcar_msi_setup_irq; > > > > > > msi->chip.teardown_irq = rcar_msi_teardown_irq; > > > > > > > > > > > > - msi->domain = irq_domain_add_linear(pcie->dev->of_node, > > > > > > INT_PCI_MSI_NR, > > > > > > + msi->domain = irq_domain_add_linear(NULL, INT_PCI_MSI_NR, > > > > > > &msi_domain_ops, &msi->chip); > > > > > > if (!msi->domain) { > > > > > > dev_err(&pdev->dev, "failed to create IRQ domain\n"); > > > > > > > > On Tegra the PCI controller is in fact the interrupt controller for > > > > MSIs. And looking at the code here it seems like the same would apply to > > > > RCAR. > > > Yes you are correct here. > > > > > > > I'm also slightly confused as to why this would cause ->msi_check() to > > > > fail. The default implementation (msi_domain_ops_check()) doesn't do > > > > anything. > > > > > > > > Also, how is passing in NULL instead of a valid struct device_node * > > > > going to prevent an oops? Perhaps this is one of those reference count > > > > imbalance bugs that have recently been showing up? > > > On arm64 (previously I didn't realise this just affects arm64, not arm), > > > the changes in commit f075915ac0b11 ("PCI/MSI: Drop domain field from > > > msi_controller") and d8a1cb757550 ("PCI/MSI: Let pci_msi_get_domain use > > > struct device::msi_domain") return an uninitialized msi domain that leads > > > to the oops. It appears that these changes assume that msi interrupt > > > controller is separate from the PCI controller. > > More accurately, when CONFIG_GENERIC_MSI_IRQ_DOMAIN is enabled, > > pci_msi_get_domain() calls dev_get_msi_domain() and at this point > > dev->msi_domain is uninitialized. > > Marc, any idea what's going on here? Thanks for putting me in the loop. No precise idea yet, but the proposed fix definitely looks like the wrong one. Actually, not passing a node identifier to any domain constructor is pretty much always a mistake when using DT. Can someone post a stack trace for this issue so that I can have a look? I'm currently traveling, so expect a slightly delayed reply... Thanks, M. -- Jazz is not dead. It just smells funny.