[Intel-gfx] [RFC PATCH] drm/i915/gt: Force mcr lock takeover if hardware forgot to release it

[Andi Shyti]

Hi,

> +	do {
> +		/*
> +		 * Starting with MTL, we need to coordinate not only with other
> +		 * driver threads, but also with hardware/firmware agents.  A
> +		 * dedicated locking register is used.
> +		 */
> +		if (GRAPHICS_VER_FULL(gt->i915) >= IP_VER(12, 70))
> +			err = wait_for(intel_uncore_read_fw(gt->uncore,
> +					      MTL_STEER_SEMAPHORE) == 0x1, 100);
> +		else
> +			break;
> +
> +		/*
> +		 * In theory we should never fail to acquire the HW semaphore;
> +		 * this would indicate some hardware/firmware is misbehaving and
> +		 * not releasing it properly.
> +		 */
> +		if (err == -ETIMEDOUT) {
> +			gt_warn(gt,
> +				"hardware MCR steering semaphore timed out "
> +				"forcing lock takeover\n");
> +			/*
> +			 * Force lock takeover
> +			 */
> +			intel_uncore_write_fw(gt->uncore,
> +					      MTL_STEER_SEMAPHORE, 0x1);
> +		}
> +	} while (err != -ETIMEDOUT);

this is '==' of course... now I missed the CI tests.

Andi