[edk2-devel] [PATCH] Platform/RaspberryPi: Always use non translating DMA in DT mode

[Jeremy Linton]

On 8/17/21 10:12 AM, Ard Biesheuvel wrote:
> On Mon, 16 Aug 2021 at 22:27, Jeremy Linton <jeremy.linton at arm.com> wrote:
>>
>> One of the many issues with the PCIe on this platform is
>> its inbound DMA is either constrained to the lower 3G, or
>> on later SoC's a translation can be used. That translation
>> was problematic with some of the OS's expected to boot
>> on this platform. So, across the board a 3G DMA limit is
>> enforced during boot. This itself causes problems because
>> the later boards removed the SPI EEPROM used by the onboard
>> XHCI controller, instead favoring using a block of RAM to
>> load its firmware. Hence it is the lower level firmware's
>> responsibility via a mailbox call, to read the bridge
>> translation/configuration before telling the XHCI controller
>> where it can find its firmware.
>>
>> Everything is great, except that it appears that Linux
>> after reprogramming the bridge to match the DT (when using
>> a translation) can't actually get the XHCI/QUIRK reset to
>> function. Apparently, because the firmware only reads the
>> bridge configuration the first time its called(?).
>>
>> So again, simplify the situation and make all DT's
>> provided by this firmware have a 3G DMA limit on the
>> PCIe bus.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton at arm.com>
> 
> This looks reasonable to me. Anyone care to ack this as well?

I would hang off on this one for a bit.

It made the machine boot, but turns out its not working like it should yet.

> 
>> ---
>>   Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c | 51 ++++++++++++++++++++++++++++
>>   1 file changed, 51 insertions(+)
>>
>> diff --git a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
>> index 0472d8ecf6..bc02cabe24 100644
>> --- a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
>> +++ b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
>> @@ -334,6 +334,52 @@ CleanSimpleFramebuffer (
>>     return EFI_SUCCESS;
>>   }
>>
>> +STATIC
>> +EFI_STATUS
>> +SyncPcie (
>> +  VOID
>> +  )
>> +{
>> +#if (RPI_MODEL == 4)
>> +  INTN          Node;
>> +  INTN          Retval;
>> +  UINT32        DmaRanges[7];
>> +
>> +  Node = fdt_path_offset (mFdtImage, "pcie0");
>> +  if (Node < 0) {
>> +    DEBUG ((DEBUG_ERROR, "%a: failed to locate 'pcie0' alias\n", __FUNCTION__));
>> +    return EFI_NOT_FOUND;
>> +  }
>> +
>> +  // non translated 32-bit DMA window with a limit of 0xc0000000
>> +  DmaRanges[0] = cpu_to_fdt32 (0x02000000);
>> +  DmaRanges[1] = cpu_to_fdt32 (0x00000000);
>> +  DmaRanges[2] = cpu_to_fdt32 (0x00000000);
>> +  DmaRanges[3] = cpu_to_fdt32 (0x00000000);
>> +  DmaRanges[4] = cpu_to_fdt32 (0x00000000);
>> +  DmaRanges[5] = cpu_to_fdt32 (0x00000000);
>> +  DmaRanges[6] = cpu_to_fdt32 (0xc0000000);
>> +
>> +  DEBUG ((DEBUG_INFO, "%a: Updating PCIe dma-ranges\n",  __FUNCTION__));
>> +
>> +  // Match dma-ranges with the edk2+ACPI setup we are using.
>> +  // This works around a failure in linux to reset the XHCI correctly
>> +  // when in DT mode following the linux kernel reprogramming the PCIe
>> +  // subsystem to match the DT supplied inbound PCIe/DMA translation.
>> +  // It appears the lower level firmware honors whatever it reads
>> +  // during the first PCI/XHCI quirk call and uses that value until
>> +  // rebooted rather than re-reading it on every mailbox command.
>> +  Retval = fdt_setprop (mFdtImage, Node, "dma-ranges",
>> +                        DmaRanges,  sizeof DmaRanges);
>> +  if (Retval != 0) {
>> +    DEBUG ((DEBUG_ERROR, "%a: failed to update 'dma-ranges' property (%d)\n",
>> +      __FUNCTION__, Retval));
>> +    return EFI_NOT_FOUND;
>> +  }
>> +#endif
>> +  return EFI_SUCCESS;
>> +}
>> +
>>   /**
>>     @param  ImageHandle   of the loaded driver
>>     @param  SystemTable   Pointer to the System Table
>> @@ -431,6 +477,11 @@ FdtDxeInitialize (
>>       Print (L"Failed to update USB compatible properties: %r\n", Status);
>>     }
>>
>> +  Status = SyncPcie ();
>> +  if (EFI_ERROR (Status)) {
>> +    Print (L"Failed to update PCIe address ranges: %r\n", Status);
>> +  }
>> +
>>     DEBUG ((DEBUG_INFO, "Installed devicetree at address %p\n", mFdtImage));
>>     Status = gBS->InstallConfigurationTable (&gFdtTableGuid, mFdtImage);
>>     if (EFI_ERROR (Status)) {
>> --
>> 2.13.7
>>



-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#79436): https://edk2.groups.io/g/devel/message/79436
Mute This Topic: https://groups.io/mt/84933264/1813853
Group Owner: devel+owner at edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [edk2-devel-archive at redhat.com]
-=-=-=-=-=-=-=-=-=-=-=-