drm/i915: FPGA_DBG is display-specific
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: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210212222049.3516344-1-matthew.d.roper@intel.com
3 files changed