Re: [PATCH 2/2] accel/ivpu: Clear specific interrupt status bits on C0

[Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>]

Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>

On 03.07.2023 10:07, Stanislaw Gruszka wrote:
> From: Karol Wachowski <karol.wachowski@linux.intel.com>
> 
> MTL C0 stepping fixed issue related to butrress interrupt status clearing,
> to clear an interrupt status it is required to write 1 to specific
> status bit field. This allows to execute read, modify and write routine.
> 
> Writing 0 will not clear the interrupt and will cause interrupt storm.
> 
> Fixes: 35b137630f08 ("accel/ivpu: Introduce a new DRM driver for Intel VPU")
> Cc: stable@vger.kernel.org # 6.3.x
> Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
> Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
> ---
>  drivers/accel/ivpu/ivpu_drv.h    |  1 +
>  drivers/accel/ivpu/ivpu_hw_mtl.c | 18 ++++++++++++------
>  2 files changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/accel/ivpu/ivpu_drv.h b/drivers/accel/ivpu/ivpu_drv.h
> index 315180dd72ce..8fe8cda2e39d 100644
> --- a/drivers/accel/ivpu/ivpu_drv.h
> +++ b/drivers/accel/ivpu/ivpu_drv.h
> @@ -75,6 +75,7 @@ struct ivpu_wa_table {
>  	bool punit_disabled;
>  	bool clear_runtime_mem;
>  	bool d3hot_after_power_off;
> +	bool interrupt_clear_with_0;
>  };
>  
>  struct ivpu_hw_info;
> diff --git a/drivers/accel/ivpu/ivpu_hw_mtl.c b/drivers/accel/ivpu/ivpu_hw_mtl.c
> index d3ba633daaa0..f1211e74017d 100644
> --- a/drivers/accel/ivpu/ivpu_hw_mtl.c
> +++ b/drivers/accel/ivpu/ivpu_hw_mtl.c
> @@ -101,6 +101,9 @@ static void ivpu_hw_wa_init(struct ivpu_device *vdev)
>  	vdev->wa.punit_disabled = ivpu_is_fpga(vdev);
>  	vdev->wa.clear_runtime_mem = false;
>  	vdev->wa.d3hot_after_power_off = true;
> +
> +	if (ivpu_device_id(vdev) == PCI_DEVICE_ID_MTL && ivpu_revision(vdev) < 4)
> +		vdev->wa.interrupt_clear_with_0 = true;
>  }
>  
>  static void ivpu_hw_timeouts_init(struct ivpu_device *vdev)
> @@ -962,12 +965,15 @@ static u32 ivpu_hw_mtl_irqb_handler(struct ivpu_device *vdev, int irq)
>  		schedule_recovery = true;
>  	}
>  
> -	/*
> -	 * Clear local interrupt status by writing 0 to all bits.
> -	 * This must be done after interrupts are cleared at the source.
> -	 * Writing 1 triggers an interrupt, so we can't perform read update write.
> -	 */
> -	REGB_WR32(MTL_BUTTRESS_INTERRUPT_STAT, 0x0);
> +	/* This must be done after interrupts are cleared at the source. */
> +	if (IVPU_WA(interrupt_clear_with_0))
> +		/*
> +		 * Writing 1 triggers an interrupt, so we can't perform read update write.
> +		 * Clear local interrupt status by writing 0 to all bits.
> +		 */
> +		REGB_WR32(MTL_BUTTRESS_INTERRUPT_STAT, 0x0);
> +	else
> +		REGB_WR32(MTL_BUTTRESS_INTERRUPT_STAT, status);
>  
>  	/* Re-enable global interrupt */
>  	REGB_WR32(MTL_BUTTRESS_GLOBAL_INT_MASK, 0x0);