[RFC] Host1x/TegraDRM UAPI
Mikko Perttunen
cyndis at kapsi.fi
Thu Jun 25 09:27:11 UTC 2020
On 6/25/20 1:33 AM, Dmitry Osipenko wrote:
> 23.06.2020 15:09, Mikko Perttunen пишет:
>> struct drm_tegra_submit_relocation {
>> /* [in] Index of GATHER or GATHER_UPTR command in commands. */
>> __u32 gather_command_index;
>>
>> /*
>> * [in] Mapping handle (obtained through CHANNEL_MAP) of the memory
>> * the address of which will be patched in.
>> */
>> __u32 mapping_id;
>>
>> /*
>> * [in] Offset in the gather that will be patched.
>> */
>> __u64 gather_offset;
>>
>> /*
>> * [in] Offset in target buffer whose paddr/IOVA will be written
>> * to the gather.
>> */
>> __u64 target_offset;
>>
>> /*
>> * [in] Number of bits the resulting address will be logically
>> * shifted right before writing to gather.
>> */
>> __u32 shift;
>>
>> __u32 reserved[1];
>> };
>
> We will also need read/write direction flag here for the
> DMA-reservations set up, it will be used for the implicit BO fencing by
> the job's scheduler.
>
Ideally on newer chips with context isolation, we no longer know what
DMA-BUFs are being used by the job at submit time - they would just be
pointers after being MAPped.
Do you know how other GPUs deal with DMA reservations - I expect
separate MAP and SUBMIT steps would be pretty common? Do you have to
pass the DMA-BUF to both steps (i.e. do IOMMU mapping during MAP, and
manage reservations at SUBMIT)?
Mikko
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