Re: [PATCH v3 1/1] drm/xe/eustall: Add WA 14027054324 support for graphics IP 35.11

["Vivekanandan, Balasubramani" <balasubramani.vivekanandan@intel.com>]

On 08.07.2026 17:06, Harish Chegondi wrote:
> WA 14027054324 is implemented in the firmware and is applied before
> EU stall sampling and reverted after EU stall sampling. The driver
> needs to notify the firmware whenever EU stall sampling is being
> enabled/disabled so that the firmware takes the necessary action.
> The driver uses a scratch pad register to communicate with the firmware.
> 
> Before enabling EU stall sampling, write 0x20 to the SWF scratch pad
> register to request the firmware to apply the workaround. The firmware
> applies the workaround and sets the scratch pad register to 0x60
> as an ACK.
> 
> Before disabling EU stall sampling, write 0x40 to the SWF scratch pad
> register to request the firmware to revert the workaround. The firmware
> reverts the workaround and sets the scratch pad register to 0 as an ACK.
> 
> The firmware is expected to take about 1 ms to apply/revert the
> workaround. 10 ms timeout is used in the driver while waiting for an
> ack from the firmware to have adequate grace period.
> 
> Bspec update for the SWF scratch pad register is still pending, but has
> been confirmed offline with the firmware team.
> 
> Bspec: 53188
> Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
> ---
> v3: 1. Make SWF_SCRATCHPAD an indexed register and move it to xe_regs.h
>     2. Use write instead of rmw to write to SWF_SCRATCHPAD register
>     3. Reduce the firmware ACK timeout to 10ms
> 
>  drivers/gpu/drm/xe/regs/xe_regs.h  |  3 +++
>  drivers/gpu/drm/xe/xe_eu_stall.c   | 38 +++++++++++++++++++++++++++---
>  drivers/gpu/drm/xe/xe_wa_oob.rules |  1 +
>  3 files changed, 39 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/regs/xe_regs.h b/drivers/gpu/drm/xe/regs/xe_regs.h
> index ad93c57edd17..6ca8b1f2440c 100644
> --- a/drivers/gpu/drm/xe/regs/xe_regs.h
> +++ b/drivers/gpu/drm/xe/regs/xe_regs.h
> @@ -7,6 +7,9 @@
>  
>  #include "regs/xe_reg_defs.h"
>  
> +#define SWF_SCRATCHPAD(_idx)			XE_REG(0x4f000 + (_idx) * 4)
> +#define   SWF_EUSTALL_MASK			REG_GENMASK(6, 5)
> +
>  #define SOC_BASE				0x280000
>  
>  #define GU_CNTL_PROTECTED			XE_REG(0x10100C)
> diff --git a/drivers/gpu/drm/xe/xe_eu_stall.c b/drivers/gpu/drm/xe/xe_eu_stall.c
> index d37770c58c5d..311b0ffa1ab2 100644
> --- a/drivers/gpu/drm/xe/xe_eu_stall.c
> +++ b/drivers/gpu/drm/xe/xe_eu_stall.c
> @@ -7,6 +7,7 @@
>  #include <linux/fs.h>
>  #include <linux/poll.h>
>  #include <linux/types.h>
> +#include <linux/iopoll.h>
>  
>  #include <drm/drm_drv.h>
>  #include <generated/xe_wa_oob.h>
> @@ -20,6 +21,7 @@
>  #include "xe_gt_printk.h"
>  #include "xe_gt_topology.h"
>  #include "xe_macros.h"
> +#include "xe_mmio.h"
>  #include "xe_observation.h"
>  #include "xe_pm.h"
>  #include "xe_trace.h"
> @@ -27,9 +29,15 @@
>  
>  #include "regs/xe_eu_stall_regs.h"
>  #include "regs/xe_gt_regs.h"
> +#include "regs/xe_regs.h"
>  
>  #define POLL_PERIOD_MS	5
>  
> +#define REQ_EUSTALL_ENABLE	0x20
> +#define ACK_EUSTALL_ENABLE	0x60
> +#define REQ_EUSTALL_DISABLE	0x40
> +#define ACK_EUSTALL_DISABLE	0
> +
>  static size_t per_xecore_buf_size = SZ_512K;
>  
>  struct per_xecore_buf {
> @@ -682,7 +690,7 @@ static int xe_eu_stall_stream_enable(struct xe_eu_stall_data_stream *stream)
>  	struct per_xecore_buf *xecore_buf;
>  	struct xe_gt *gt = stream->gt;
>  	u16 group, instance;
> -	int xecore;
> +	int xecore, ret = 0;
>  
>  	/* Take runtime pm ref and forcewake to disable RC6 */
>  	xe_pm_runtime_get(gt_to_xe(gt));
> @@ -693,6 +701,19 @@ static int xe_eu_stall_stream_enable(struct xe_eu_stall_data_stream *stream)
>  		return -ETIMEDOUT;
>  	}
>  
> +	if (XE_GT_WA(gt, 14027054324)) {
> +		/* Request the firmware to apply the workaround and wait for an ACK */
> +		xe_mmio_write32(&gt->mmio, SWF_SCRATCHPAD(0), REQ_EUSTALL_ENABLE);
> +		ret = read_poll_timeout(xe_mmio_read32, reg_value,
> +					(reg_value & SWF_EUSTALL_MASK) == ACK_EUSTALL_ENABLE,
> +					1000, 10000, true, &gt->mmio, SWF_SCRATCHPAD(0));

for polling can you use the function xe_mmio_wait32, which is more
appropriate.

> +		if (ret) {
> +			xe_gt_err(gt, "Timeout polling for EU stall enable ACK from firmware\n");
> +			xe_force_wake_put(gt_to_fw(gt), stream->fw_ref);
> +			xe_pm_runtime_put(gt_to_xe(gt));
> +			return ret;
> +		}
> +	}
>  	if (XE_GT_WA(gt, 22016596838))
>  		xe_gt_mcr_multicast_write(gt, ROW_CHICKEN2,
>  					  REG_MASKED_FIELD_ENABLE(DISABLE_DOP_GATING));
> @@ -730,7 +751,7 @@ static int xe_eu_stall_stream_enable(struct xe_eu_stall_data_stream *stream)
>  	reg_value |= XEHPC_EUSTALL_BASE_ENABLE_SAMPLING;
>  	xe_gt_mcr_multicast_write(gt, XEHPC_EUSTALL_BASE, reg_value);
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static void eu_stall_data_buf_poll_work_fn(struct work_struct *work)
> @@ -840,6 +861,8 @@ static int xe_eu_stall_enable_locked(struct xe_eu_stall_data_stream *stream)
>  static int xe_eu_stall_disable_locked(struct xe_eu_stall_data_stream *stream)
>  {
>  	struct xe_gt *gt = stream->gt;
> +	u32 reg_value;
> +	int ret = 0;
>  
>  	if (!stream->enabled)
>  		return 0;
> @@ -853,11 +876,20 @@ static int xe_eu_stall_disable_locked(struct xe_eu_stall_data_stream *stream)
>  	if (XE_GT_WA(gt, 22016596838))
>  		xe_gt_mcr_multicast_write(gt, ROW_CHICKEN2,
>  					  REG_MASKED_FIELD_DISABLE(DISABLE_DOP_GATING));
> +	if (XE_GT_WA(gt, 14027054324)) {
> +		/* Request the firmware to revert the workaround and wait for an ACK */
> +		xe_mmio_write32(&gt->mmio, SWF_SCRATCHPAD(0), REQ_EUSTALL_DISABLE);
> +		ret = read_poll_timeout(xe_mmio_read32, reg_value,
> +					(reg_value & SWF_EUSTALL_MASK) == ACK_EUSTALL_DISABLE,
> +					1000, 10000, true, &gt->mmio, SWF_SCRATCHPAD(0));

same here.

Regards,
Bala

> +		if (ret)
> +			xe_gt_err(gt, "Timeout polling for EU stall disable ACK from firmware\n");
> +	}
>  
>  	xe_force_wake_put(gt_to_fw(gt), stream->fw_ref);
>  	xe_pm_runtime_put(gt_to_xe(gt));
>  
> -	return 0;
> +	return ret;
>  }
>  
>  static long xe_eu_stall_stream_ioctl_locked(struct xe_eu_stall_data_stream *stream,
> diff --git a/drivers/gpu/drm/xe/xe_wa_oob.rules b/drivers/gpu/drm/xe/xe_wa_oob.rules
> index 9027365f0043..41734b9672c5 100644
> --- a/drivers/gpu/drm/xe/xe_wa_oob.rules
> +++ b/drivers/gpu/drm/xe/xe_wa_oob.rules
> @@ -66,3 +66,4 @@
>  14025883347	MEDIA_VERSION_RANGE(1301, 3503)
>  		GRAPHICS_VERSION_RANGE(2004, 3005)
>  16029380221	MEDIA_VERSION(3500)
> +14027054324	GRAPHICS_VERSION(3511)
> -- 
> 2.43.0
>