Hey Christoph,
Thanks for taking time to review
the series.
On 2020-03-16 21:20, Christoph Hellwig wrote:
On Mon, Mar 09, 2020 at 11:52:52PM +0530, Sibi Sankar wrote:
The Q6 modem sub-system has direct access to DDR through memnoc and
an indirect access routed through a SMMU which MSS CE (crypto engine
sub-component of MSS) uses during out of reset sequence. Request
direct
mapping for the modem-firmware subdevice since smmu is not expected
to provide access control/translation for these SIDs (sandboxing of
the
modem is achieved through XPUs engaged using SMC calls).
Please fix your device tree so that the device isn't bound to an
IOMMU.
the bindings proposed in the series
would add a sub-device with an iommu
property.
modem_pil: remoteproc@xxxxx {
...
modem-firmware {
iommus = <&apps_smmu 0x460 0x1>;
};
...
};
Remoteproc device will not have a iommu
property but modem-firmware sub-device
will.
With ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT y,
we would want to configure the SID either
in direct mapping or bypass (either will
do since protection is achieved through
other means)
https://lore.kernel.org/lkml/497e40b8-300f-1b83-4312-93a58c459d1d@xxxxxxx/
Currently the restructuring is trending
towards whats discussed in the ^^ thread.
i.e either direct mapping/bypass will be
done in the SoC specific corner of the
SMMU driver.
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