On Wed, Oct 04, 2023 at 08:30:21AM -0500, Rob Herring wrote: > On Tue, Oct 03, 2023 at 09:52:13AM +0530, shravan chippa wrote: > > From: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx> > > > > Add new compatible name microchip,mpfs-pdma to support > > out of order dma transfers > > > > Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > Signed-off-by: Shravan Chippa <shravan.chippa@xxxxxxxxxxxxx> > > --- > > .../bindings/dma/sifive,fu540-c000-pdma.yaml | 12 ++++++++---- > > 1 file changed, 8 insertions(+), 4 deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml > > index a1af0b906365..974467c4bacb 100644 > > --- a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml > > +++ b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml > > @@ -27,10 +27,14 @@ allOf: > > > > properties: > > compatible: > > - items: > > - - enum: > > - - sifive,fu540-c000-pdma > > - - const: sifive,pdma0 > > + oneOf: > > + - items: > > + - const: microchip,mpfs-pdma # Microchip out of order DMA transfer > > + - const: sifive,fu540-c000-pdma # Sifive in-order DMA transfer IIRC I asked for the comments here to be removed on the previous version, and my r-b was conditional on that. The device specific compatible has merit outside of the ordering, which may just be a software policy decision. > This doesn't really make sense. microchip,mpfs-pdma is compatible with > sifive,fu540-c000-pdma and sifive,fu540-c000-pdma is compatible with > sifive,pdma0, but microchip,mpfs-pdma is not compatible with > sifive,pdma0? (Or replace "compatible with" with "a superset of") TBH, I am not sure why it was done this way. Probably because the driver contains both sifive,pdma0 and sifive,fu540-c000-pdma. Doing compatible = "microchip,mpfs-pdma", "sifive,fu540-c000-pdma", "sifive,pdma0"; thing would be fine. > Any fallback is only useful if an OS only understanding the fallback > will work with the h/w. Does this h/w work without the driver changes? Yes. I've been hoping that someone from SiFive would come along, and in response to this patchset, tell us _why_ the driver does not make use of out-of-order transfers to begin with. Thanks, Conor.
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