[lkml]   [2021]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v4 4/8] of: property: Add fw_devlink support for optional properties
On Tue, Feb 9, 2021 at 1:33 PM Rob Herring <> wrote:
> On Fri, Feb 05, 2021 at 02:26:40PM -0800, Saravana Kannan wrote:
> > Not all DT bindings are mandatory bindings. Add support for optional DT
> > bindings and mark iommus, iommu-map, dmas as optional DT bindings.
> I don't think we can say these are optional or not. It's got to be a
> driver decision somehow.

Right, so maybe the word "optional" isn't a good name for it. I can
change that if you want.

The point being, fw_devlink can't block the probe of this driver based
on iommu property. We let the driver decide if it wants to
-EPROBE_DEFER or not or however it wants to handle this.

> For example, if IOMMU is optional, what happens with this sequence:
> driver probes without IOMMU
> driver calls dma_map_?()
> IOMMU driver probes
> h/w accesses DMA buffer --> BOOM!

Right. But how is this really related to fw_devlink? AFAICT, this is
an issue even today. If the driver needs the IOMMU, then it needs to
make sure the IOMMU has probed? What am I missing?


 \ /
  Last update: 2021-02-10 02:34    [W:0.194 / U:0.036 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site