Thread (18 messages) 18 messages, 5 authors, 2021-04-05

Re: [PATCH 4/4] dt-bindings: spi: Convert cadence-quadspi.txt to cadence-quadspi.yaml

From: Pratyush Yadav <hidden>
Date: 2021-04-01 08:58:03
Also in: linux-devicetree, linux-spi, lkml

On 01/04/21 01:57PM, Vignesh Raghavendra wrote:

On 3/29/21 11:52 PM, Pratyush Yadav wrote:
quoted
quoted
quoted
+  cdns,fifo-depth:
+    description:
+      Size of the data FIFO in words.
+    $ref: "/schemas/types.yaml#/definitions/uint32"
+    enum: [ 128, 256 ]
+    default: 128
+
+  cdns,fifo-width:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Bus width of the data FIFO in bytes.
+    default: 4
I assume there's some constraints on this?
IIUC this is a matter of how the peripheral is implemented and there are 
no clear constraints. Different implementations can use different bus 
widths for the SRAM bus but I don't see any mention of minimum or 
maximum values. FWIW, all users in the kernel use a 4 byte bus.
IMO a safe constraint would be to set a range of 1 to 4 (8/16/24/32 bit
wide) given this represents SRAM bus width. Binding can always be
updated if there exists an implementation with higher SRAM bus
width/fifo-width (although that's highly unlikely given there are no
such examples today).

But leaving it open ended with range of 0 to UINT_MAX sounds incorrect
to me.
Ok. Will respin.
quoted
quoted
With that,

Reviewed-by: Rob Herring <robh@kernel.org>
Thanks.
-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.

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