• Matt Roper's avatar
    drm/i915: FPGA_DBG is display-specific · a321c3c6
    Matt Roper authored
    Although the bspec's description doesn't make it very clear, the
    hardware architects have confirmed that the FPGA_DBG register that we
    use to check for unclaimed MMIO accesses is display-specific and will
    only properly flag unclaimed MMIO transactions for registers in the
    display range.  If a platform doesn't have display, FPGA_DBG itself will
    not be available and should not be checked.  Let's move the feature flag
    into intel_device_info.display to more accurately reflect this.
    
    Given that we now know FPGA_DBG is display-specific, it could be argued
    that we should only check it on out intel_de_*() functions.  However
    let's not make that change right now; keeping the checks in all of the
    existing locations still helps us catch cases where regular
    intel_uncore_*() functions use bad MMIO offset math / base addresses and
    accidentally wind up landing within an unused area within the display
    MMIO range.  It will also help catch cases where userspace-initiated
    MMIO (e.g., IGT's intel_reg tool) attempt to read bad offsets within the
    display range.
    
    v2:  Add missing hunk with the update to the HAS_FPGA_DBG_UNCLAIMED
         macro.  (CI)
    
    Cc: Lucas De Marchi <lucas.demarchi@intel.com>
    Signed-off-by: default avatarMatt Roper <matthew.d.roper@intel.com>
    Reviewed-by: default avatarLucas De Marchi <lucas.demarchi@intel.com>
    Link: https://patchwork.freedesktop.org/patch/msgid/20210212222049.3516344-1-matthew.d.roper@intel.com
    a321c3c6
intel_device_info.h 6.07 KB