Re: [PATCH] iommu: silence iommu group prints

[Russell King - ARM Linux admin <linux@armlinux.org.uk>]

On Wed, Mar 04, 2020 at 10:56:06AM +0200, Laurentiu Tudor wrote:
> 
> On 04.03.2020 00:17, Russell King - ARM Linux admin wrote:
> > On Tue, Mar 03, 2020 at 05:55:05PM +0200, Laurentiu Tudor wrote:
> > >  From c98dc05cdd45ae923654f2427985bd28bcde4bb2 Mon Sep 17 00:00:00 2001
> > > From: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> > > Date: Thu, 13 Feb 2020 11:59:12 +0200
> > > Subject: [PATCH 1/4] bus: fsl-mc: add custom .dma_configure implementation
> > > Content-Type: text/plain; charset="us-ascii"
> > > 
> > > The devices on this bus are not discovered by way of device tree
> > > but by queries to the firmware. It makes little sense to trick the
> > > generic of layer into thinking that these devices are of related so
> > > that we can get our dma configuration. Instead of doing that, add
> > > our custom dma configuration implementation.
> > 
> > Firstly, applying this to v5.5 results in a build failure, due to a
> > missing linux/iommu.h include.
> > 
> > Secondly, this on its own appears to make the DPAA2 network interfaces
> > completely disappear.  Looking in /sys/bus/fsl-mc/drivers/*, none of
> > the DPAA2 drivers are bound to anything, and looking in
> > /sys/bus/fsl-mc/devices/, there is:
> > 
> > lrwxrwxrwx 1 root root 0 Mar  3 22:06 dprc.1 -> ../../../devices/platform/soc/80c000000.fsl-mc/dprc.1
> > 
> > This is booting with u-boot, so using DT rather than ACPI.
> > 
> > > Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> > > ---
> > >   drivers/bus/fsl-mc/fsl-mc-bus.c | 42 ++++++++++++++++++++++++++++++++-
> > >   1 file changed, 41 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
> > > index 36eb25f82c8e..3df015eedae4 100644
> > > --- a/drivers/bus/fsl-mc/fsl-mc-bus.c
> > > +++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
> > > @@ -132,11 +132,51 @@ static int fsl_mc_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
> > >   static int fsl_mc_dma_configure(struct device *dev)
> > >   {
> > >   	struct device *dma_dev = dev;
> > > +	struct iommu_fwspec *fwspec;
> > > +	const struct iommu_ops *iommu_ops;
> > > +	struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
> > > +	int ret;
> > > +	u32 icid;
> > > +
> > > +	/* Skip DMA setup for devices that are not DMA masters */
> > > +	if (dev->type == &fsl_mc_bus_dpmcp_type ||
> > > +	    dev->type == &fsl_mc_bus_dpbp_type ||
> > > +	    dev->type == &fsl_mc_bus_dpcon_type ||
> > > +	    dev->type == &fsl_mc_bus_dpio_type)
> > > +		return 0;
> > >   	while (dev_is_fsl_mc(dma_dev))
> > >   		dma_dev = dma_dev->parent;
> > > -	return of_dma_configure(dev, dma_dev->of_node, 0);
> > > +	fwspec = dev_iommu_fwspec_get(dma_dev);
> > > +	if (!fwspec)
> > > +		return -ENODEV;
> > 
> > The problem appears to be here - fwspec is NULL for dprc.1.
> 
> Ok, that's because the iommu config is missing from the DT node that's
> exposing the MC firmware. I've attached a fresh set of patches that include
> on top the missing config and a workaround that makes MC work over SMMU.
> Also added the missing #include, thanks for pointing out.
> Let me know how it goes.

Shouldn't patch 6 should be first in the series, so that patch 1 does
not cause a regression and bisectability damage?

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