Re: [PATCH] i2c: ismt: Provide a DMA buffer for Interrupt Cause Logging

[Wolfram Sang <wsa@kernel.org>]

[-- Attachment #1: Type: text/plain, Size: 1098 bytes --]

On Wed, Apr 27, 2022 at 01:19:10PM +0300, Mika Westerberg wrote:
> Before sending a MSI the hardware writes information pertinent to the
> interrupt cause to a memory location pointed by SMTICL register. This
> memory holds three double words where the least significant bit tells
> whether the interrupt cause of master/target/error is valid. The driver
> does not use this but we need to set it up because otherwise it will
> perform DMA write to the default address (0) and this will cause an
> IOMMU fault such as below:
> 
>   DMAR: DRHD: handling fault status reg 2
>   DMAR: [DMA Write] Request device [00:12.0] PASID ffffffff fault addr 0
>         [fault reason 05] PTE Write access is not set
> 
> To prevent this from happening, provide a proper DMA buffer for this
> that then gets mapped by the IOMMU accordingly.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

No maintainer response so far, but given this looks like an important
bugfix and you guys are all from Intel as well, I'll apply it this time.

Applied to for-current, thanks!


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]