Re: [Intel-gfx] [PATCH] drm/i915/mtl: Add MC6 Wa_14017210380 for SAMedia

["Nilawar, Badal" <badal.nilawar@intel.com>]

Hi Matt,

On 01-11-2022 20:47, Matt Roper wrote:
> On Sat, Oct 29, 2022 at 12:59:35AM +0530, Badal Nilawar wrote:
>> This workaround is added for Media Tile of MTL A step. It is to help
>> pcode workaround which handles the hardware bug seen on CXL splitter
>> during package C2/C3 transitins due to MC6 entry/exit. As a part of
>> workaround pcode expect kmd to send mailbox message "media busy" when
>> components of Media tile is in use and "media not busy" when not in use.
>> As per workaround description gucrc need to be disabled so enabled
>> host based RC for Media tile.
>>
>> HSD: 14017210380
>>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
>> Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_gt_pm.c     | 33 +++++++++++++++++++++++
>>   drivers/gpu/drm/i915/gt/uc/intel_guc_rc.c | 13 ++++++++-
>>   drivers/gpu/drm/i915/i915_drv.h           |  4 +++
>>   drivers/gpu/drm/i915/i915_reg.h           |  9 +++++++
>>   4 files changed, 58 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>> index f553e2173bda..398dbeb298ca 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
>> @@ -19,10 +19,37 @@
>>   #include "intel_rc6.h"
>>   #include "intel_rps.h"
>>   #include "intel_wakeref.h"
>> +#include "intel_pcode.h"
>>   #include "pxp/intel_pxp_pm.h"
>>   
>>   #define I915_GT_SUSPEND_IDLE_TIMEOUT (HZ / 2)
>>   
>> +/*
>> + * Wa_14017210380: mtl
>> + */
> 
> This doesn't appear to be a valid workaround number; workaround numbers
> are always supposed to be the "lineage" numbers from the workaround
> database.  Wa_14017073508 seems to be related; is that the one you're
> implementing?
Thanks for pointing out I will correct the workaround number in next 
revision.
> 
>> +
>> +static bool mtl_needs_media_mc6_wa(struct intel_gt *gt)
> 
> Drive-by comment:  names like this aren't great since even though
> there's only one "media MC6" workaround today, that may not be true in
> the future.
I think its better to drop this function and replace its calls below 
with (IS_MTL_GRAPHICS_STEP(gt->i915, P, STEP_A0, STEP_B0) && gt->type == 
GT_MEDIA)

Regards,
Badal
> 
> 
> Matt
> 
>> +{
>> +	return (IS_MTL_GRAPHICS_STEP(gt->i915, P, STEP_A0, STEP_B0) &&
>> +		gt->type == GT_MEDIA);
>> +}
>> +
>> +static void mtl_mc6_wa_media_busy(struct intel_gt *gt)
>> +{
>> +	if (mtl_needs_media_mc6_wa(gt))
>> +		snb_pcode_write_p(gt->uncore, PCODE_MBOX_GT_STATE,
>> +				  PCODE_MBOX_GT_STATE_MEDIA_BUSY,
>> +				  PCODE_MBOX_GT_STATE_DOMAIN_MEDIA, 0);
>> +}
>> +
>> +static void mtl_mc6_wa_media_not_busy(struct intel_gt *gt)
>> +{
>> +	if (mtl_needs_media_mc6_wa(gt))
>> +		snb_pcode_write_p(gt->uncore, PCODE_MBOX_GT_STATE,
>> +				  PCODE_MBOX_GT_STATE_MEDIA_NOT_BUSY,
>> +				  PCODE_MBOX_GT_STATE_DOMAIN_MEDIA, 0);
>> +}
>> +
>>   static void user_forcewake(struct intel_gt *gt, bool suspend)
>>   {
>>   	int count = atomic_read(&gt->user_wakeref);
>> @@ -70,6 +97,9 @@ static int __gt_unpark(struct intel_wakeref *wf)
>>   
>>   	GT_TRACE(gt, "\n");
>>   
>> +	/* Wa_14017210380: mtl */
>> +	mtl_mc6_wa_media_busy(gt);
>> +
>>   	/*
>>   	 * It seems that the DMC likes to transition between the DC states a lot
>>   	 * when there are no connected displays (no active power domains) during
>> @@ -119,6 +149,9 @@ static int __gt_park(struct intel_wakeref *wf)
>>   	GEM_BUG_ON(!wakeref);
>>   	intel_display_power_put_async(i915, POWER_DOMAIN_GT_IRQ, wakeref);
>>   
>> +	/* Wa_14017210380: mtl */
>> +	mtl_mc6_wa_media_not_busy(gt);
>> +
>>   	return 0;
>>   }
>>   
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_rc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_rc.c
>> index 8f8dd05835c5..cc6356ff84a5 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_rc.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_rc.c
>> @@ -11,9 +11,20 @@
>>   
>>   static bool __guc_rc_supported(struct intel_guc *guc)
>>   {
>> +	struct intel_gt *gt = guc_to_gt(guc);
>> +
>> +	/*
>> +	 * Wa_14017210380: mtl
>> +	 * Do not enable gucrc to avoid additional interrupts which
>> +	 * may disrupt pcode wa.
>> +	 */
>> +	if (IS_MTL_GRAPHICS_STEP(gt->i915, P, STEP_A0, STEP_B0) &&
>> +	    gt->type == GT_MEDIA)
>> +		return false;
>> +
>>   	/* GuC RC is unavailable for pre-Gen12 */
>>   	return guc->submission_supported &&
>> -		GRAPHICS_VER(guc_to_gt(guc)->i915) >= 12;
>> +		GRAPHICS_VER(gt->i915) >= 12;
>>   }
>>   
>>   static bool __guc_rc_selected(struct intel_guc *guc)
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index 05b3300cc4ed..659b92382ff2 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -740,6 +740,10 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
>>   #define IS_XEHPSDV_GRAPHICS_STEP(__i915, since, until) \
>>   	(IS_XEHPSDV(__i915) && IS_GRAPHICS_STEP(__i915, since, until))
>>   
>> +#define IS_MTL_GRAPHICS_STEP(__i915, variant, since, until) \
>> +	(IS_SUBPLATFORM(__i915, INTEL_METEORLAKE, INTEL_SUBPLATFORM_##variant) && \
>> +	 IS_GRAPHICS_STEP(__i915, since, until))
>> +
>>   /*
>>    * DG2 hardware steppings are a bit unusual.  The hardware design was forked to
>>    * create three variants (G10, G11, and G12) which each have distinct
>> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>> index 1c0da50c0dc7..abe62cea083d 100644
>> --- a/drivers/gpu/drm/i915/i915_reg.h
>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>> @@ -6678,6 +6678,15 @@
>>   /*   XEHP_PCODE_FREQUENCY_CONFIG param2 */
>>   #define     PCODE_MBOX_DOMAIN_NONE		0x0
>>   #define     PCODE_MBOX_DOMAIN_MEDIAFF		0x3
>> +
>> +/* Wa_14017210380: mtl */
>> +#define   PCODE_MBOX_GT_STATE			0x50
>> +/* sub-commands (param1) */
>> +#define     PCODE_MBOX_GT_STATE_MEDIA_BUSY	0x1
>> +#define     PCODE_MBOX_GT_STATE_MEDIA_NOT_BUSY	0x2
>> +/* param2 */
>> +#define     PCODE_MBOX_GT_STATE_DOMAIN_MEDIA	0x1
>> +
>>   #define GEN6_PCODE_DATA				_MMIO(0x138128)
>>   #define   GEN6_PCODE_FREQ_IA_RATIO_SHIFT	8
>>   #define   GEN6_PCODE_FREQ_RING_RATIO_SHIFT	16
>> -- 
>> 2.25.1
>>
>