1. 30 Dec, 2019 3 commits
    • Andre Przywara's avatar
      plat: rpi4: Skip UART initialisation · 0eda713b
      Andre Przywara authored
      
      
      So far we have seen two different clock setups for the Raspberry Pi 4
      board, with the VPU clock divider being different. This was handled by
      reading the divider register and adjusting the base clock rate
      accordingly.
      Recently a new GPU firmware version appeared that changed the clock rate
      *again*, though this time at a higher level, so the VPU rate (and the
      apparent PLLC parent clock) did not seem to change, judging by reading
      the clock registers.
      So rather than playing cat and mouse with the GPU firmware or going
      further down the rabbit hole of exploring the whole clock tree, let's
      just skip the baud rate programming altogether. This works because the
      GPU firmware actually sets up and programs the debug UART already, so
      we can just use it.
      
      Pass 0 as the base clock rate to let the console driver skip the setup,
      also remove the no longer needed clock code.
      Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
      Change-Id: Ica88a3f3c9c11059357c1e6dd8f7a4d9b1f98fd7
      0eda713b
    • Andre Przywara's avatar
      console: 16550: Prepare for skipping initialisation · cd50ffd2
      Andre Przywara authored
      
      
      On some platforms the UART might have already been initialised, for
      instance by firmware running before TF-A or by a separate management
      processor. In this case it would not be need to initialise it again
      (doing so could create spurious characters). But more importantly this
      saves us from knowing the right baudrate and the right base clock rate
      for the UART. This can lead to more robust and versatile firmware builds.
      
      Allow to skip the 16550 UART initialisation and baud rate divisor
      programming, by interpreting an input clock rate of "0" to signify this
      case. This will just skip the call to console_16550_core_init, but still
      will register the console properly.
      
      Users should just pass 0 as the second parameter, the baudrate (third
      parameter) will then be ignored as well.
      
      Fix copy & paste typos in comments for the console_16550_register()
      function on the way.
      Signed-off-by: default avatarAndre Przywara <andre.przywara@arm.com>
      Change-Id: I9f8fca5b358f878fac0f31dc411358fd160786ee
      cd50ffd2
    • Manish Pandey's avatar
      2b4c5e4b
  2. 26 Dec, 2019 1 commit
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