diff mbox series

[02/25] dt-bindings: net: dwmac: Extend number of PBL values

Message ID 20201214091616.13545-3-Sergey.Semin@baikalelectronics.ru
State Superseded
Headers show
Series net: stmmac: Fix clocks/reset-related procedures | expand

Commit Message

Serge Semin Dec. 14, 2020, 9:15 a.m. UTC
In accordance with [1] the permitted PBL values can be set as one of
[1, 2, 4, 8, 16, 32]. The rest of the values results in undefined
behavior. At the same time some of the permitted values can be also
invalid depending on the controller FIFOs size and the data bus width.
Seeing due to having too many variables all the possible PBL property
constraints can't be implemented in the bindings schema, let's extend
the set of permitted PBL values to be as much as the configuration
register supports leaving the undefined behaviour cases for developers
to handle.

[1] DesignWare Cores Ethernet MAC Universal Databook, Revision 3.73a,
    October 2013, p. 380.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
 Documentation/devicetree/bindings/net/snps,dwmac.yaml | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

Comments

Rob Herring (Arm) Dec. 15, 2020, 5:14 p.m. UTC | #1
On Mon, 14 Dec 2020 12:15:52 +0300, Serge Semin wrote:
> In accordance with [1] the permitted PBL values can be set as one of

> [1, 2, 4, 8, 16, 32]. The rest of the values results in undefined

> behavior. At the same time some of the permitted values can be also

> invalid depending on the controller FIFOs size and the data bus width.

> Seeing due to having too many variables all the possible PBL property

> constraints can't be implemented in the bindings schema, let's extend

> the set of permitted PBL values to be as much as the configuration

> register supports leaving the undefined behaviour cases for developers

> to handle.

> 

> [1] DesignWare Cores Ethernet MAC Universal Databook, Revision 3.73a,

>     October 2013, p. 380.

> 

> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>

> ---

>  Documentation/devicetree/bindings/net/snps,dwmac.yaml | 11 +++++++----

>  1 file changed, 7 insertions(+), 4 deletions(-)

> 


Reviewed-by: Rob Herring <robh@kernel.org>
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
index 4b672499f20d..e084fbbf976e 100644
--- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
+++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
@@ -264,23 +264,26 @@  properties:
 
   snps,pbl:
     description:
-      Programmable Burst Length (tx and rx)
+      Programmable Burst Length (tx and rx). Note some of these values
+      can be still invalid due to HW limitations connected with the data
+      bus width and the FIFOs depth, so a total length of a single DMA
+      burst shouldn't exceed half the FIFO depth.
     $ref: /schemas/types.yaml#definitions/uint32
-    enum: [2, 4, 8]
+    enum: [1, 2, 4, 8, 16, 32]
 
   snps,txpbl:
     description:
       Tx Programmable Burst Length. If set, DMA tx will use this
       value rather than snps,pbl.
     $ref: /schemas/types.yaml#definitions/uint32
-    enum: [2, 4, 8]
+    enum: [1, 2, 4, 8, 16, 32]
 
   snps,rxpbl:
     description:
       Rx Programmable Burst Length. If set, DMA rx will use this
       value rather than snps,pbl.
     $ref: /schemas/types.yaml#definitions/uint32
-    enum: [2, 4, 8]
+    enum: [1, 2, 4, 8, 16, 32]
 
   snps,no-pbl-x8:
     $ref: /schemas/types.yaml#definitions/flag