Re: [PATCH 1/2] Platform/Raspberrypi: Update DMA constants based on SOC revision

["Pete Batard" <pete@akeo.ie>]

Two minor notes below:

On 2021.05.11 23:41, Jeremy Linton wrote:
> The newer BCM2711 SoC's don't have a DMA constraint on the emmc2
> controller. So we don't need to do the 1G translation. Lets
> allow the AML to detect the SoC revision and return a different
> _DMA resource.
> 
> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
> ---
>   Platform/RaspberryPi/AcpiTables/Emmc.asl           | 39 +++++++++++++++++++++-
>   .../Bcm27xx/Include/IndustryStandard/Bcm2711.h     |  2 ++
>   2 files changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/Platform/RaspberryPi/AcpiTables/Emmc.asl b/Platform/RaspberryPi/AcpiTables/Emmc.asl
> index 23febe37b4..c6691e81dc 100644
> --- a/Platform/RaspberryPi/AcpiTables/Emmc.asl
> +++ b/Platform/RaspberryPi/AcpiTables/Emmc.asl
> @@ -8,6 +8,7 @@
>   
>   #include <IndustryStandard/Bcm2836SdHost.h>
>   #include <IndustryStandard/Bcm2836Sdio.h>
> +#include <IndustryStandard/Bcm2711.h>
>   
>   #include "AcpiTables.h"
>   
> @@ -31,7 +32,8 @@ DefinitionBlock (__FILE__, "SSDT", 2, "RPIFDN", "RPI4EMMC", 2)
>           Return (^RBUF)
>         }
>   
> -      Name (_DMA, ResourceTemplate() {
> +      // Translated DMA region for < C0

Even if the code makes it clear that we're testing the chip revision to 
decide what region to return, I would prefer if we had "for pre C0 
revisions of the SoC" instead of "for < C0", as I suspect people who 
read this too quickly, and have no idea what C0, refers to may think 
we're talking about a DMA address boundary or something.

> +      Name (DMTR, ResourceTemplate() {
>           QWordMemory (ResourceProducer,
>             ,
>             MinFixed,
> @@ -48,6 +50,41 @@ DefinitionBlock (__FILE__, "SSDT", 2, "RPIFDN", "RPI4EMMC", 2)
>           )
>         })
>   
> +      // Non translated DMA region for >= C0

Same as above: "for post C0 revisions of the SoC"

> +      Name (DMNT, ResourceTemplate() {
> +        QWordMemory (ResourceProducer,
> +          ,
> +          MinFixed,
> +          MaxFixed,
> +          NonCacheable,
> +          ReadWrite,
> +          0x0,
> +          0x0000000000000000, // MIN
> +          0x000000FFFFFFFFFF, // MAX
> +          0x0000000000000000, // TRA
> +          0x0000010000000000, // LEN
> +          ,
> +          ,
> +        )
> +      })
> +
> +      Method (_DMA, 0x0, Serialized)
> +      {
> +        OperationRegion (CHPR, SystemMemory, ID_CHIPREV, 0x4)
> +          Field (CHPR, DWordAcc, NoLock, Preserve) {
> +            SOCI, 32
> +        }
> +
> +        if ((SOCI & 0xFF) >= 0x20)
> +        {
> +          return (^DMNT);
> +        }
> +        else
> +        {
> +          return (^DMTR);
> +        }
> +      }
> +
>         // emmc2 Host Controller. (brcm,bcm2711-emmc2)
>         Device (SDC3)
>         {
> diff --git a/Silicon/Broadcom/Bcm27xx/Include/IndustryStandard/Bcm2711.h b/Silicon/Broadcom/Bcm27xx/Include/IndustryStandard/Bcm2711.h
> index 86906b2438..8a69128d11 100644
> --- a/Silicon/Broadcom/Bcm27xx/Include/IndustryStandard/Bcm2711.h
> +++ b/Silicon/Broadcom/Bcm27xx/Include/IndustryStandard/Bcm2711.h
> @@ -88,4 +88,6 @@
>   
>   #define THERM_SENSOR               0xfd5d2200
>   
> +#define ID_CHIPREV                 0xfc404000
> +
>   #endif /* BCM2711_H__ */
> 

With the comment changes, if agreed, applicable during integration:
Reviewed-by: Pete Batard <pete@akeo.ie>