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

["Ard Biesheuvel" <ardb@kernel.org>]

On Wed, 12 May 2021 at 13:19, Pete Batard <pete@akeo.ie> wrote:
>
> 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>

Thanks Pete. I have pushed these 2 patches as
e1efa61c33f7..09c5ab125b61 with the above suggestion applied.