[Intel-gfx] [CI] drm/i915/uncore: keep track of last mmio accesses

[Lucas De Marchi]

On Mon, Apr 04, 2022 at 10:34:53AM -0700, Lucas De Marchi wrote:
>Sine gen6 we use FPGA_DBG register to detect unclaimed MMIO registers.
>This register is in the display engine IP and can only ever detect
>unclaimed accesses to registers in this area. However sometimes there
>are reports of this triggering for registers in other areas, which
>should not be possible.
>
>This keeps track of the last 4 registers which should hopefully be
>sufficient to understand where these are coming from. And without
>increasing the debug struct too much:
>
>Before:
>	struct intel_uncore_mmio_debug {
>		spinlock_t                 lock;                 /*     0    64 */
>		/* --- cacheline 1 boundary (64 bytes) --- */
>		int                        unclaimed_mmio_check; /*    64     4 */
>		int                        saved_mmio_check;     /*    68     4 */
>		u32                        suspend_count;        /*    72     4 */
>
>		/* size: 80, cachelines: 2, members: 4 */
>		/* padding: 4 */
>		/* last cacheline: 16 bytes */
>	};
>
>After:
>	struct intel_uncore_mmio_debug {
>		spinlock_t                 lock;                 /*     0    64 */
>		/* --- cacheline 1 boundary (64 bytes) --- */
>		int                        unclaimed_mmio_check; /*    64     4 */
>		int                        saved_mmio_check;     /*    68     4 */
>		u32                        last_reg[4];          /*    72    16 */
>		u32                        last_reg_pos;         /*    88     4 */
>		u32                        suspend_count;        /*    92     4 */
>
>		/* size: 96, cachelines: 2, members: 6 */
>		/* last cacheline: 32 bytes */
>	};
>
>Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
>---
>
>Sending this for CI only for now, to get it running and hopefully
>reproduce the issues we are seeing. I didn't reproduce the issue
>mentioned with this patch applied yet.

nvm, found a way to reproduce it locally and fix up the output
reporting. I canceled the CI execution and will submit it again.

Lucas De Marchi