Re: [PATCH 19/20] drm/i915/lmem: don't treat small BAR as an error

[Matthew Auld <matthew.auld@intel.com>]

On 03/02/2022 09:48, Thomas Hellström wrote:
> 
> On 1/26/22 16:21, Matthew Auld wrote:
>> Just pass along the probed io_size. The backend should be able to
>> utilize the entire range here, even if some of it is non-mappable.
> Changes here LGTM.
>>
>> It does leave open with what to do with stolen local-memory.
> 
> Are objects in stolen local required to be mappable?

 From a quick look I don't really see such users on discrete, outside of 
maybe intelfb_create(), where I guess the initial fb might be located in 
stolen on DG1. But from DG2+ it looks like it will just be located in 
normal LMEM. For that I was thinking we add something like 
i915_gem_object_create_region_at(), and somehow wire that up to the 
{fpfn, lpfn}...

> 
> /Thomas
> 
> 
>>
>> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
>> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_region_lmem.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_region_lmem.c 
>> b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
>> index 2c7ec7ff79fd..b788fc2b3df8 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_region_lmem.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_region_lmem.c
>> @@ -200,6 +200,7 @@ static struct intel_memory_region 
>> *setup_lmem(struct intel_gt *gt)
>>       struct intel_memory_region *mem;
>>       resource_size_t min_page_size;
>>       resource_size_t io_start;
>> +    resource_size_t io_size;
>>       resource_size_t lmem_size;
>>       int err;
>> @@ -210,7 +211,8 @@ static struct intel_memory_region 
>> *setup_lmem(struct intel_gt *gt)
>>       lmem_size = intel_uncore_read64(uncore, GEN12_GSMBASE);
>>       io_start = pci_resource_start(pdev, 2);
>> -    if (GEM_WARN_ON(lmem_size > pci_resource_len(pdev, 2)))
>> +    io_size = min(pci_resource_len(pdev, 2), lmem_size);
>> +    if (!io_size)
>>           return ERR_PTR(-ENODEV);
>>       min_page_size = HAS_64K_PAGES(i915) ? I915_GTT_PAGE_SIZE_64K :
>> @@ -220,7 +222,7 @@ static struct intel_memory_region 
>> *setup_lmem(struct intel_gt *gt)
>>                        lmem_size,
>>                        min_page_size,
>>                        io_start,
>> -                     lmem_size,
>> +                     io_size,
>>                        INTEL_MEMORY_LOCAL,
>>                        0,
>>                        &intel_region_lmem_ops);