linux-kernel - Re: [PATCH 1/3] dt-bindings: dma: ti: k3-bcdma: Describe cfg register regions

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Date:   Fri, 11 Aug 2023 10:08:17 +0530
From:   Vignesh Raghavendra <vigneshr@...com>
To:     Conor Dooley <conor@...nel.org>
CC:     Peter Ujfalusi <peter.ujfalusi@...il.com>,
        Vinod Koul <vkoul@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        <dmaengine@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/3] dt-bindings: dma: ti: k3-bcdma: Describe cfg register
 regions



On 11/08/23 00:05, Conor Dooley wrote:
> On Thu, Aug 10, 2023 at 11:13:53PM +0530, Vignesh Raghavendra wrote:
>> Block copy DMA(BCDMA)module on K3 SoCs have ring cfg, TX and RX
>> channel cfg register regions which are usually configured by a Device
>> Management firmware. But certain entities such as bootloader (like
>> U-Boot) may have to access them directly. Describe this region in the
>> binding documentation for completeness of module description.
>>
>> Keep the binding compatible with existing DTS files by requiring first
>> five regions to be present at least.
>>
>> Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
>> ---
>>  .../devicetree/bindings/dma/ti/k3-bcdma.yaml  | 25 +++++++++++++------
>>  1 file changed, 17 insertions(+), 8 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/dma/ti/k3-bcdma.yaml b/Documentation/devicetree/bindings/dma/ti/k3-bcdma.yaml
>> index 4ca300a42a99..d166e284532b 100644
>> --- a/Documentation/devicetree/bindings/dma/ti/k3-bcdma.yaml
>> +++ b/Documentation/devicetree/bindings/dma/ti/k3-bcdma.yaml
>> @@ -37,11 +37,11 @@ properties:
>>  
>>    reg:
>>      minItems: 3
>> -    maxItems: 5
>> +    maxItems: 8
> 
> How come none of these reg entries have a description? What
> differentiates a "gcfg" from a "cfg" for example?
> 

Ok, I will a patch to describe the regions first before adding new ones.

>>  
>>    reg-names:
>>      minItems: 3
>> -    maxItems: 5
>> +    maxItems: 8
>>  
>>    "#dma-cells":
>>      const: 3
>> @@ -161,14 +161,19 @@ allOf:
>>        properties:
>>          reg:
>>            minItems: 5
>> +          maxItems: 8
>>  
>>          reg-names:
>> +          minItems: 5
>>            items:
>>              - const: gcfg
>>              - const: bchanrt
>>              - const: rchanrt
>>              - const: tchanrt
>>              - const: ringrt
>> +            - const: cfg
>> +            - const: tchan
>> +            - const: rchan
>>  
>>        required:
>>          - ti,sci-rm-range-bchan
>> @@ -216,12 +221,16 @@ examples:
>>              main_bcdma: dma-controller@...c0100 {
>>                  compatible = "ti,am64-dmss-bcdma";
>>  
>> -                reg = <0x0 0x485c0100 0x0 0x100>,
>> -                      <0x0 0x4c000000 0x0 0x20000>,
>> -                      <0x0 0x4a820000 0x0 0x20000>,
>> -                      <0x0 0x4aa40000 0x0 0x20000>,
>> -                      <0x0 0x4bc00000 0x0 0x100000>;
>> -                reg-names = "gcfg", "bchanrt", "rchanrt", "tchanrt", "ringrt";
>> +                reg = <0x00 0x485c0100 0x00 0x100>,
> 
> Why have you added extra zeros? (0x00)

Sorry, copy paste error, was trying to copy example from real DT that
use 0x00. Will fix. Thanks!

> 
> Thanks,
> Conor.
> 
>> +                      <0x00 0x4c000000 0x00 0x20000>,
>> +                      <0x00 0x4a820000 0x00 0x20000>,
>> +                      <0x00 0x4aa40000 0x00 0x20000>,
>> +                      <0x00 0x4bc00000 0x00 0x100000>,
>> +                      <0x00 0x48600000 0x00 0x8000>,
>> +                      <0x00 0x484a4000 0x00 0x2000>,
>> +                      <0x00 0x484c2000 0x00 0x2000>;
>> +                reg-names = "gcfg", "bchanrt", "rchanrt", "tchanrt", "ringrt",
>> +                            "cfg", "tchan", "rchan";
>>                  msi-parent = <&inta_main_dmss>;
>>                  #dma-cells = <3>;
>>  
>> -- 
>> 2.41.0
>>

-- 
Regards
Vignesh