[PATCH 2/3] drm/etnaviv: Map and unmap the GPU VA range with respect to its user size
Sui Jingfeng
sui.jingfeng at linux.dev
Sat Oct 26 05:55:18 UTC 2024
Hi,
On 2024/10/7 18:17, Lucas Stach wrote:
>>
>> @@ -104,21 +108,7 @@ static int etnaviv_iommu_map(struct etnaviv_iommu_context *context, u32 iova,
>> static void etnaviv_iommu_unmap(struct etnaviv_iommu_context *context, u32 iova,
>> struct sg_table *sgt, unsigned len)
>> {
>> - struct scatterlist *sg;
>> - unsigned int da = iova;
>> - int i;
>> -
>> - for_each_sgtable_dma_sg(sgt, sg, i) {
>> - size_t bytes = sg_dma_len(sg) + sg->offset;
Why the length of a single SG segment is `sg_dma_len(sg) + sg->offset` here?
>> - etnaviv_context_unmap(context, da, bytes);
>> -
>> - VERB("unmap[%d]: %08x(%zx)", i, iova, bytes);
>> -
>> - BUG_ON(!PAGE_ALIGNED(bytes));
>> -
>> - da += bytes;
>> - }
>> + etnaviv_context_unmap(context, iova, len);
> This drops some sanity checks, but I have only ever seen them fire when
> we had other kernel memory corruption issues, so I'm fine with the
> simplification you did here.
Isn't that 'sg_dma_len(sg)' itself is the length of its backing memory ?
> Regards,
> Lucas
--
Best regards,
Sui
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