linux-kernel - Re: [Intel-gfx] [PATCH v5 1/5] drm/i915: add needs_compact

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Message-ID: <19bf8290-9308-b5c6-eb73-4020fa81aa66@collabora.com>
Date:   Wed, 26 Jan 2022 17:11:41 +0000
From:   Robert Beckett <bob.beckett@...labora.com>
To:     Thomas Hellström (Intel) 
        <thomas_os@...pmail.org>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org,
        Matthew Auld <matthew.auld@...el.com>
Subject: Re: [Intel-gfx] [PATCH v5 1/5] drm/i915: add needs_compact_pt flag



On 26/01/2022 13:49, Thomas Hellström (Intel) wrote:
> 
> On 1/25/22 20:35, Robert Beckett wrote:
>> From: Ramalingam C <ramalingam.c@...el.com>
>>
>> Add a new platform flag, needs_compact_pt, to mark the requirement of
>> compact pt layout support for the ppGTT when using 64K GTT pages.
>>
>> With this flag has_64k_pages will only indicate requirement of 64K
>> GTT page sizes or larger for device local memory access.
>>
>> Suggested-by: Matthew Auld <matthew.auld@...el.com>
>> Signed-off-by: Ramalingam C <ramalingam.c@...el.com>
>> Signed-off-by: Robert Beckett <bob.beckett@...labora.com>
>> ---
>>   drivers/gpu/drm/i915/i915_drv.h          | 10 +++++++---
>>   drivers/gpu/drm/i915/i915_pci.c          |  2 ++
>>   drivers/gpu/drm/i915/intel_device_info.h |  1 +
>>   3 files changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h 
>> b/drivers/gpu/drm/i915/i915_drv.h
>> index 44c1f98144b4..1258b7779705 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -1512,12 +1512,16 @@ IS_SUBPLATFORM(const struct drm_i915_private 
>> *i915,
>>   /*
>>    * Set this flag, when platform requires 64K GTT page sizes or 
>> larger for
>> - * device local memory access. Also this flag implies that we require or
>> - * at least support the compact PT layout for the ppGTT when using 
>> the 64K
>> - * GTT pages.
> 
> Why do we remove these comment lines?
Because HAS_64K_PAGES now means just 64K page, it no longer means also 
requires compact pt.
This is to support other products that will have 64K but not have the 
PDE non-sharing restriction in future.

Those lines moved to the next change NEEDS_COMPACT_PT, which is now 
separate.

> 
> 
>> + * device local memory access.
>>    */
>>   #define HAS_64K_PAGES(dev_priv) (INTEL_INFO(dev_priv)->has_64k_pages)
>> +/* Set this flag when platform doesn't allow both 64k pages and 4k 
>> pages in
> 
> First line of multi-line comments should be empty.
thanks. I'm surprised checkpatch didnt spot that.

> 
> 
>> + * the same PT. this flag means we need to support compact PT layout 
>> for the
>> + * ppGTT when using the 64K GTT pages.
>> + */
>> +#define NEEDS_COMPACT_PT(dev_priv) 
>> (INTEL_INFO(dev_priv)->needs_compact_pt)
>> +
>>   #define HAS_IPC(dev_priv)         
>> (INTEL_INFO(dev_priv)->display.has_ipc)
>>   #define HAS_REGION(i915, i) (INTEL_INFO(i915)->memory_regions & (i))
>> diff --git a/drivers/gpu/drm/i915/i915_pci.c 
>> b/drivers/gpu/drm/i915/i915_pci.c
>> index 4081fd50ba9d..799b56569ef5 100644
>> --- a/drivers/gpu/drm/i915/i915_pci.c
>> +++ b/drivers/gpu/drm/i915/i915_pci.c
>> @@ -1028,6 +1028,7 @@ static const struct intel_device_info 
>> xehpsdv_info = {
>>       PLATFORM(INTEL_XEHPSDV),
>>       .display = { },
>>       .has_64k_pages = 1,
>> +    .needs_compact_pt = 1,
>>       .platform_engine_mask =
>>           BIT(RCS0) | BIT(BCS0) |
>>           BIT(VECS0) | BIT(VECS1) | BIT(VECS2) | BIT(VECS3) |
>> @@ -1045,6 +1046,7 @@ static const struct intel_device_info dg2_info = {
>>       .media.rel = 55,
>>       PLATFORM(INTEL_DG2),
>>       .has_64k_pages = 1,
>> +    .needs_compact_pt = 1,
>>       .platform_engine_mask =
>>           BIT(RCS0) | BIT(BCS0) |
>>           BIT(VECS0) | BIT(VECS1) |
>> diff --git a/drivers/gpu/drm/i915/intel_device_info.h 
>> b/drivers/gpu/drm/i915/intel_device_info.h
>> index 3699b1c539ea..c8aaf646430c 100644
>> --- a/drivers/gpu/drm/i915/intel_device_info.h
>> +++ b/drivers/gpu/drm/i915/intel_device_info.h
>> @@ -130,6 +130,7 @@ enum intel_ppgtt_type {
>>       /* Keep has_* in alphabetical order */ \
>>       func(has_64bit_reloc); \
>>       func(has_64k_pages); \
>> +    func(needs_compact_pt); \
>>       func(gpu_reset_clobbers_display); \
>>       func(has_reset_engine); \
>>       func(has_global_mocs); \