diff mbox series

[4/7] dt-bindings: dma: allwinner,sun50i-a64-dma: Add compatible for H616

Message ID 20240122170518.3090814-5-wens@kernel.org
State New
Headers show
Series None | expand

Commit Message

Chen-Yu Tsai Jan. 22, 2024, 5:05 p.m. UTC 
From: Chen-Yu Tsai <wens@csie.org>

The DMA controllers found on the H616 and H618 are the same as the one
found on the H6. The only difference is the DMA endpoint (DRQ) layout.

Since the number of channels and endpoints are described with additional
generic properties, just add a new H616-specific compatible string and
fallback to the H6 one.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
 .../bindings/dma/allwinner,sun50i-a64-dma.yaml    | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

Comments

Chen-Yu Tsai Jan. 25, 2024, 2:37 p.m. UTC | #1 
On Tue, Jan 23, 2024 at 8:41 AM Andre Przywara <andre.przywara@arm.com> wrote:
>
> On Tue, 23 Jan 2024 01:05:15 +0800
> Chen-Yu Tsai <wens@kernel.org> wrote:
>
> Hi,
>
> > From: Chen-Yu Tsai <wens@csie.org>
> >
> > The DMA controllers found on the H616 and H618 are the same as the one
> > found on the H6. The only difference is the DMA endpoint (DRQ) layout.
>
> That does not seem to be entirely true: The H616 encodes the two lowest
> bits in DMA_DESC_ADDR_REG differently: on the H6 they must be 0 (word
> aligned), on the H616 these contain bits [33:32] of the address of the
> DMA descriptor. The manual doesn't describe the descriptor format in
> much detail, but ec31c5c59492 suggests that those two bits are put in
> the "para" word of the descriptor.

Good catch. So, same as the A100 I believe?

> The good thing it that this encoding is backwards compatible, so I
> think the fallback string still holds: Any driver just implementing the
> H6 encoding would be able to drive the H616.
>
> I think the A100 was mis-described, as mentioned here:
> https://lore.kernel.org/linux-arm-kernel/29e575b6-14cb-73f1-512d-9f0f934490ea@arm.com/
> I think we should:
> - make the A100 use: "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
> - make the H616 use: "allwinner,sun50i-h616-dma", "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
>
> Does that make sense?

I wouldn't call that exactly backward compatible. Say the driver forgot to
clear the two bits. It would work fine on the H6, but the accessed address
could be way off on the A100 and H616.


ChenYu

> Cheers,
> Andre
>
> > Since the number of channels and endpoints are described with additional
> > generic properties, just add a new H616-specific compatible string and
> > fallback to the H6 one.
> >
> > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> > ---
> >  .../bindings/dma/allwinner,sun50i-a64-dma.yaml    | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > index ec2d7a789ffe..e5693be378bd 100644
> > --- a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > +++ b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > @@ -28,6 +28,9 @@ properties:
> >        - items:
> >            - const: allwinner,sun8i-r40-dma
> >            - const: allwinner,sun50i-a64-dma
> > +      - items:
> > +          - const: allwinner,sun50i-h616-dma
> > +          - const: allwinner,sun50i-h6-dma
> >
> >    reg:
> >      maxItems: 1
> > @@ -59,10 +62,14 @@ required:
> >  if:
> >    properties:
> >      compatible:
> > -      enum:
> > -        - allwinner,sun20i-d1-dma
> > -        - allwinner,sun50i-a100-dma
> > -        - allwinner,sun50i-h6-dma
> > +      oneOf:
> > +        - enum:
> > +            - allwinner,sun20i-d1-dma
> > +            - allwinner,sun50i-a100-dma
> > +            - allwinner,sun50i-h6-dma
> > +        - items:
> > +            - const: allwinner,sun50i-h616-dma
> > +            - const: allwinner,sun50i-h6-dma
> >
> >  then:
> >    properties:
>
Andre Przywara Jan. 25, 2024, 3:09 p.m. UTC | #2 
On Thu, 25 Jan 2024 22:37:34 +0800
Chen-Yu Tsai <wens@kernel.org> wrote:

Hi,

> On Tue, Jan 23, 2024 at 8:41 AM Andre Przywara <andre.przywara@arm.com> wrote:
> >
> > On Tue, 23 Jan 2024 01:05:15 +0800
> > Chen-Yu Tsai <wens@kernel.org> wrote:
> >
> > Hi,
> >  
> > > From: Chen-Yu Tsai <wens@csie.org>
> > >
> > > The DMA controllers found on the H616 and H618 are the same as the one
> > > found on the H6. The only difference is the DMA endpoint (DRQ) layout.  
> >
> > That does not seem to be entirely true: The H616 encodes the two lowest
> > bits in DMA_DESC_ADDR_REG differently: on the H6 they must be 0 (word
> > aligned), on the H616 these contain bits [33:32] of the address of the
> > DMA descriptor. The manual doesn't describe the descriptor format in
> > much detail, but ec31c5c59492 suggests that those two bits are put in
> > the "para" word of the descriptor.  
> 
> Good catch. So, same as the A100 I believe?

Yes, that's what I got as well.

> > The good thing it that this encoding is backwards compatible, so I
> > think the fallback string still holds: Any driver just implementing the
> > H6 encoding would be able to drive the H616.
> >
> > I think the A100 was mis-described, as mentioned here:
> > https://lore.kernel.org/linux-arm-kernel/29e575b6-14cb-73f1-512d-9f0f934490ea@arm.com/
> > I think we should:
> > - make the A100 use: "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
> > - make the H616 use: "allwinner,sun50i-h616-dma", "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
> >
> > Does that make sense?  
> 
> I wouldn't call that exactly backward compatible. Say the driver forgot to
> clear the two bits. It would work fine on the H6, but the accessed address
> could be way off on the A100 and H616.

I don't know the exact boundaries of "compatible" here, but the H6 manual
pretty clearly states "The descriptor address must be word-aligned."
But since the A100 compatible is known and supported for a while, that
doesn't really matter, practically speaking, I guess.

One could check how the H6 DMA controller reacts to those bits not being
0, not sure if I find the time, though.

Cheers,
Andre.

> > Cheers,
> > Andre
> >  
> > > Since the number of channels and endpoints are described with additional
> > > generic properties, just add a new H616-specific compatible string and
> > > fallback to the H6 one.
> > >
> > > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> > > ---
> > >  .../bindings/dma/allwinner,sun50i-a64-dma.yaml    | 15 +++++++++++----
> > >  1 file changed, 11 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > > index ec2d7a789ffe..e5693be378bd 100644
> > > --- a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > > +++ b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
> > > @@ -28,6 +28,9 @@ properties:
> > >        - items:
> > >            - const: allwinner,sun8i-r40-dma
> > >            - const: allwinner,sun50i-a64-dma
> > > +      - items:
> > > +          - const: allwinner,sun50i-h616-dma
> > > +          - const: allwinner,sun50i-h6-dma
> > >
> > >    reg:
> > >      maxItems: 1
> > > @@ -59,10 +62,14 @@ required:
> > >  if:
> > >    properties:
> > >      compatible:
> > > -      enum:
> > > -        - allwinner,sun20i-d1-dma
> > > -        - allwinner,sun50i-a100-dma
> > > -        - allwinner,sun50i-h6-dma
> > > +      oneOf:
> > > +        - enum:
> > > +            - allwinner,sun20i-d1-dma
> > > +            - allwinner,sun50i-a100-dma
> > > +            - allwinner,sun50i-h6-dma
> > > +        - items:
> > > +            - const: allwinner,sun50i-h616-dma
> > > +            - const: allwinner,sun50i-h6-dma
> > >
> > >  then:
> > >    properties:  
> >  
>
Chen-Yu Tsai Jan. 25, 2024, 3:45 p.m. UTC | #3 
On Thu, Jan 25, 2024 at 11:09 PM Andre Przywara <andre.przywara@arm.com> wrote:
>
> On Thu, 25 Jan 2024 22:37:34 +0800
> Chen-Yu Tsai <wens@kernel.org> wrote:
>
> Hi,
>
> > On Tue, Jan 23, 2024 at 8:41 AM Andre Przywara <andre.przywara@arm.com> wrote:
> > >
> > > On Tue, 23 Jan 2024 01:05:15 +0800
> > > Chen-Yu Tsai <wens@kernel.org> wrote:
> > >
> > > Hi,
> > >
> > > > From: Chen-Yu Tsai <wens@csie.org>
> > > >
> > > > The DMA controllers found on the H616 and H618 are the same as the one
> > > > found on the H6. The only difference is the DMA endpoint (DRQ) layout.
> > >
> > > That does not seem to be entirely true: The H616 encodes the two lowest
> > > bits in DMA_DESC_ADDR_REG differently: on the H6 they must be 0 (word
> > > aligned), on the H616 these contain bits [33:32] of the address of the
> > > DMA descriptor. The manual doesn't describe the descriptor format in
> > > much detail, but ec31c5c59492 suggests that those two bits are put in
> > > the "para" word of the descriptor.
> >
> > Good catch. So, same as the A100 I believe?
>
> Yes, that's what I got as well.
>
> > > The good thing it that this encoding is backwards compatible, so I
> > > think the fallback string still holds: Any driver just implementing the
> > > H6 encoding would be able to drive the H616.
> > >
> > > I think the A100 was mis-described, as mentioned here:
> > > https://lore.kernel.org/linux-arm-kernel/29e575b6-14cb-73f1-512d-9f0f934490ea@arm.com/
> > > I think we should:
> > > - make the A100 use: "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
> > > - make the H616 use: "allwinner,sun50i-h616-dma", "allwinner,sun50i-a100-dma", "sun50i-h6-dma"
> > >
> > > Does that make sense?
> >
> > I wouldn't call that exactly backward compatible. Say the driver forgot to
> > clear the two bits. It would work fine on the H6, but the accessed address
> > could be way off on the A100 and H616.
>
> I don't know the exact boundaries of "compatible" here, but the H6 manual
> pretty clearly states "The descriptor address must be word-aligned."
> But since the A100 compatible is known and supported for a while, that
> doesn't really matter, practically speaking, I guess.

I'd say that makes the descriptor address register backward compatible,

> One could check how the H6 DMA controller reacts to those bits not being
> 0, not sure if I find the time, though.

but no idea about the parameter field in the descriptor. So for now I
think we should just be cautious. Since as you mentioned the A100 is already
supported and listed separately, lets just keep that for now.

ChenYu

[...]
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
index ec2d7a789ffe..e5693be378bd 100644
--- a/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
+++ b/Documentation/devicetree/bindings/dma/allwinner,sun50i-a64-dma.yaml
@@ -28,6 +28,9 @@  properties:
       - items:
           - const: allwinner,sun8i-r40-dma
           - const: allwinner,sun50i-a64-dma
+      - items:
+          - const: allwinner,sun50i-h616-dma
+          - const: allwinner,sun50i-h6-dma
 
   reg:
     maxItems: 1
@@ -59,10 +62,14 @@  required:
 if:
   properties:
     compatible:
-      enum:
-        - allwinner,sun20i-d1-dma
-        - allwinner,sun50i-a100-dma
-        - allwinner,sun50i-h6-dma
+      oneOf:
+        - enum:
+            - allwinner,sun20i-d1-dma
+            - allwinner,sun50i-a100-dma
+            - allwinner,sun50i-h6-dma
+        - items:
+            - const: allwinner,sun50i-h616-dma
+            - const: allwinner,sun50i-h6-dma
 
 then:
   properties: