From: thomas.petazzoni@free-electrons•com (Thomas Petazzoni)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v2] PCI: layerscape: Add PCIe support for LS1043a and LS2080a
Date: Mon, 12 Oct 2015 09:15:44 +0200 [thread overview]
Message-ID: <20151012091544.7dbbe330@free-electrons.com> (raw)
In-Reply-To: <20151011191027.GA29221@localhost>
Bjorn,
On Sun, 11 Oct 2015 14:10:27 -0500, Bjorn Helgaas wrote:
> > driver/of/irq.c void of_msi_configure(struct device *dev, struct
> > device_node *np) will bind "msi-parent" to each device if there is
> > "msi-parent" handler. The PCIe driver do not need to do anything. If
> > we do not check "msi-parent" here, we will have no chance to check it.
> > The common code of 'of' and 'pci' bus driver will not complain,
> > because the msi controller may be found by other way.
>
> Hmm. In mvebu_pcie_msi_enable() and xgene_pcie_msi_enable(), we
> also look for "msi-parent". If that fails, mvebu continues silently
> and xgene complains (but only if CONFIG_PCI_MSI=y).
I don't really have the context of the discussion here. But the reason
why the mvebu pcie driver silently continues if msi-parent is missing
is because we initially introduced the PCIe mvebu Device Tree binding
without MSI support. When we later added MSI support thanks to the
msi-parent property, we wanted to preserve backward compatibility with
old DTs that didn't had the msi-parent property. Such DTs would
continue to work, albeit without the MSI functionality obviously.
Other drivers that had the MSI functionality from day 1 may want to
make such a property mandatory rather than optional.
Best regards,
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
next prev parent reply other threads:[~2015-10-12 7:15 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-17 9:13 [PATCH v2] PCI: layerscape: Add PCIe support for LS1043a and LS2080a Minghuan Lian
2015-10-07 17:57 ` Bjorn Helgaas
2015-10-11 19:10 ` Bjorn Helgaas
2015-10-12 1:47 ` Duc Dang
2015-10-12 2:53 ` Lian M.H.
2015-10-12 23:02 ` Duc Dang
2015-10-12 7:15 ` Thomas Petazzoni [this message]
2015-10-12 12:36 ` Arnd Bergmann
2015-10-12 15:26 ` Bjorn Helgaas
2015-10-13 1:37 ` Lian M.H.
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