Hello,
FYI: This patch was reviewed when it was part of another patchset:
http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200817234033.442511-4-leobra...@gmail.com/
On Thu, 2021-03-18 at 14:44 -0300, Leonardo Bras wrote:
> As of today, doing iommu_range_alloc() only for !largealloc (npages <= 15)
> will only be able to use 3/4 of the available pages, given pages on
> largepool not being available for !largealloc.
>
> This could mean some drivers not being able to fully use all the available
> pages for the DMA window.
>
> Add pages on largepool as a last resort for !largealloc, making all pages
> of the DMA window available.
>
> Signed-off-by: Leonardo Bras
> Reviewed-by: Alexey Kardashevskiy
> ---
> arch/powerpc/kernel/iommu.c | 9 +
> 1 file changed, 9 insertions(+)
>
> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
> index 3329ef045805..ae6ad8dca605 100644
> --- a/arch/powerpc/kernel/iommu.c
> +++ b/arch/powerpc/kernel/iommu.c
> @@ -255,6 +255,15 @@ static unsigned long iommu_range_alloc(struct device
> *dev,
> pass++;
> goto again;
>
>
> + } else if (pass == tbl->nr_pools + 1) {
> + /* Last resort: try largepool */
> + spin_unlock(&pool->lock);
> + pool = &tbl->large_pool;
> + spin_lock(&pool->lock);
> + pool->hint = pool->start;
> + pass++;
> + goto again;
> +
> } else {
> /* Give up */
> spin_unlock_irqrestore(&(pool->lock), flags);
