Re: [edk2-platforms][PATCH v2 1/1] Platform/RaspberryPi: Fix mini UART clock divisor calculation

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

On 2021.04.08 12:06, Ard Biesheuvel wrote:
> On Thu, 8 Apr 2021 at 11:47, Pete Batard <pete@akeo.ie> wrote:
>>
>> On 2021.04.06 15:04, Mario Bălănică wrote:
>>> The VPU clock divisor has changed in this commit:
>>> https://github.com/raspberrypi/firmware/commit/1e5456a,
>>> thus breaking the mini UART clock divisor calculation on the Pi 4.
>>>
>>> Fix this by reading the core clock from the mailbox instead.
>>>
>>> Signed-off-by: Mario Bălănică <mariobalanica02@gmail.com>
>>> ---
>>>    Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c   | 15 +++------------
>>>    Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S |  4 ----
>>>    Platform/RaspberryPi/RPi4/RPi4.dsc                                   |  6 ++++--
>>>    3 files changed, 7 insertions(+), 18 deletions(-)
>>>
>>> diff --git a/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c b/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
>>> index 5e83bbf022eb..d2f983bf0a9f 100644
>>> --- a/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
>>> +++ b/Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.c
>>> @@ -34,25 +34,16 @@ SerialPortGetDivisor (
>>>      UINT32  SerialBaudRate
>>>
>>>    )
>>>
>>>    {
>>>
>>> -  UINT64              BaseClockRate;
>>>
>>> +  UINT32              BaseClockRate;
>>>
>>>      UINT32              Divisor;
>>>
>>>
>>>
>>> -  //
>>>
>>> -  // On the Raspberry Pi, the clock to use for the 16650-compatible UART
>>>
>>> -  // is the base clock divided by the 12.12 fixed point VPU clock divisor.
>>>
>>> -  //
>>>
>>> -  BaseClockRate = (UINT64)PcdGet32 (PcdSerialClockRate);
>>>
>>> -#if (RPI_MODEL == 4)
>>>
>>> -  Divisor = MmioRead32(BCM2836_CM_BASE + BCM2836_CM_VPU_CLOCK_DIVISOR) & 0xFFFFFF;
>>>
>>> -  if (Divisor != 0)
>>>
>>> -    BaseClockRate = (BaseClockRate << 12) / Divisor;
>>>
>>> -#endif
>>>
>>> +  BaseClockRate = PcdGet32 (PcdSerialClockRate);
>>>
>>>
>>>
>>>      //
>>>
>>>      // As per the BCM2xxx datasheets:
>>>
>>>      // baudrate = system_clock_freq / (8 * (divisor + 1)).
>>>
>>>      //
>>>
>>> -  Divisor = (UINT32)BaseClockRate / (SerialBaudRate * 8);
>>>
>>> +  Divisor = BaseClockRate / (SerialBaudRate * 8);
>>>
>>>      if (Divisor != 0) {
>>>
>>>        Divisor--;
>>>
>>>      }
>>>
>>> diff --git a/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S b/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
>>> index 58351e4fb8cc..7008aaf8aa4c 100644
>>> --- a/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
>>> +++ b/Platform/RaspberryPi/Library/PlatformLib/AArch64/RaspberryPiHelper.S
>>> @@ -85,13 +85,11 @@ ASM_FUNC (ArmPlatformPeiBootAction)
>>>        adr     x2, mBoardRevision
>>>
>>>        str     w0, [x2]
>>>
>>>
>>>
>>> -#if (RPI_MODEL == 3)
>>>
>>>        run     .Lclkinfo_buffer
>>>
>>>
>>>
>>>        ldr     w0, .Lfrequency
>>>
>>>        adr     x2, _gPcd_BinaryPatch_PcdSerialClockRate
>>>
>>>        str     w0, [x2]
>>>
>>> -#endif
>>>
>>>
>>>
>>>        ret
>>>
>>>
>>>
>>> @@ -135,7 +133,6 @@ ASM_FUNC (ArmPlatformPeiBootAction)
>>>        .long   0                           // end tag
>>>
>>>        .set    .Lrevinfo_size, . - .Lrevinfo_buffer
>>>
>>>
>>>
>>> -#if (RPI_MODEL == 3)
>>>
>>>        .align  4
>>>
>>>    .Lclkinfo_buffer:
>>>
>>>        .long   .Lclkinfo_size
>>>
>>> @@ -148,7 +145,6 @@ ASM_FUNC (ArmPlatformPeiBootAction)
>>>        .long   0                           // frequency
>>>
>>>        .long   0                           // end tag
>>>
>>>        .set    .Lclkinfo_size, . - .Lclkinfo_buffer
>>>
>>> -#endif
>>>
>>>
>>>
>>>    //UINTN
>>>
>>>    //ArmPlatformGetPrimaryCoreMpId (
>>>
>>> diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc b/Platform/RaspberryPi/RPi4/RPi4.dsc
>>> index 2c05c31118d2..ff802d8347ea 100644
>>> --- a/Platform/RaspberryPi/RPi4/RPi4.dsc
>>> +++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
>>> @@ -429,7 +429,6 @@ [PcdsFixedAtBuild.common]
>>>      gArmPlatformTokenSpaceGuid.PL011UartClkInHz|48000000
>>>
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio|TRUE
>>>
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterStride|4
>>>
>>> -  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate|1000000000
>>>
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdSerialFifoControl|0x27
>>>
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdSerialExtendedTxFifoSize|8
>>>
>>>      gEfiMdePkgTokenSpaceGuid.PcdUartDefaultBaudRate|115200
>>>
>>> @@ -465,6 +464,9 @@ [PcdsFixedAtBuild.common]
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdFirmwareVendor|L"EDK2"
>>>
>>>      gEfiMdeModulePkgTokenSpaceGuid.PcdSetNxForStack|TRUE
>>>
>>>
>>>
>>> +[PcdsPatchableInModule]
>>>
>>> +  gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate|500000000
>>>
>>> +
>>>
>>>    [PcdsDynamicHii.common.DEFAULT]
>>>
>>>
>>>
>>>      #
>>>
>>> @@ -621,7 +623,7 @@ [Components.common]
>>>      MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
>>>
>>>      MdeModulePkg/Universal/SerialDxe/SerialDxe.inf {
>>>
>>>        <LibraryClasses>
>>>
>>> -      SerialPortLib|Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortLib.inf
>>>
>>> +      SerialPortLib|Platform/RaspberryPi/Library/DualSerialPortLib/DualSerialPortDxeLib.inf
>>>
>>>      }
>>>
>>>      Platform/RaspberryPi/Drivers/DisplayDxe/DisplayDxe.inf
>>>
>>>      EmbeddedPkg/Drivers/ConsolePrefDxe/ConsolePrefDxe.inf
>>>
>>
>> Reviewed-by: Pete Batard <pete@akeo.ie>
>> Tested-by: Pete Batard <pete@akeo.ie>
> 
> Thanks Pete.
> 
> Could anyone get me a version of this patch that is not whitespace
> mangled? This one does not apply with 'git am'
> 

Done.

The version I sent is the one I applied & tested after I ran it through 
my unmangling script to remove the extra lines.

Not sure if it'll still not be re-mangled by the list processing though.

Regards,

/Pete