drm/i915: Sanitycheck MMIO access early in driver load
We occasionally see the PCI device in a non-accessible state at the point the driver is loaded. When this happens, all BAR accesses will read back as 0xFFFFFFFF. Rather than reading registers and misinterpreting their (invalid) values, let's specifically check for 0xFFFFFFFF in a register that cannot have that value to see if the device is accessible. Signed-off-by: Matt Roper <matthew.d.roper@intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com> Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20230327195547.356584-2-andi.shyti@linux.intel.com
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