linux-kernel - Re: [PATCH 5/5] nouveau/ttm/PCIe: Use dma

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Date:	Thu, 27 Jan 2011 16:22:12 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	dri-devel@...ts.freedesktop.org, thomas@...pmail.org,
	airlied@...ux.ie, linux-kernel@...r.kernel.org,
	Ben Skeggs <bskeggs@...hat.com>,
	Jerome Glisse <jglisse@...hat.com>
Cc:	konrad@...nok.org
Subject: Re: [PATCH 5/5] nouveau/ttm/PCIe: Use dma_addr if TTM has set it.

On Fri, Jan 07, 2011 at 12:11:44PM -0500, Konrad Rzeszutek Wilk wrote:
> If the TTM layer has used the DMA API to setup pages that are
> TTM_PAGE_FLAG_DMA32 (look at patch titled: "ttm: Utilize the dma_addr_t
> array for pages that are to in DMA32 pool."), lets use it
> when programming the GART in the PCIe type cards.
> 
> This patch skips doing the pci_map_page (and pci_unmap_page) if
> there is a DMA addresses passed in for that page. If the dma_address
> is zero (or DMA_ERROR_CODE), then we continue on with our old
> behaviour.

Hey Ben and Jerome,

I should have CC-ed you guys earlier but missed that and instead just
CC-ed the mailing list. I was wondering what your thoughts are
about this patchset? Thomas took a look at the patchset and he is OK
but more eyes never hurt.


> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_sgdma.c |   28 +++++++++++++++++++++-------
>  1 files changed, 21 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_sgdma.c b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> index edc140a..bbdd982 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_sgdma.c
> @@ -12,6 +12,7 @@ struct nouveau_sgdma_be {
>  	struct drm_device *dev;
>  
>  	dma_addr_t *pages;
> +	bool *ttm_alloced;
>  	unsigned nr_pages;
>  
>  	unsigned pte_start;
> @@ -35,15 +36,25 @@ nouveau_sgdma_populate(struct ttm_backend *be, unsigned long num_pages,
>  	if (!nvbe->pages)
>  		return -ENOMEM;
>  
> +	nvbe->ttm_alloced = kmalloc(sizeof(bool) * num_pages, GFP_KERNEL);
> +	if (!nvbe->ttm_alloced)
> +		return -ENOMEM;
> +
>  	nvbe->nr_pages = 0;
>  	while (num_pages--) {
> -		nvbe->pages[nvbe->nr_pages] =
> -			pci_map_page(dev->pdev, pages[nvbe->nr_pages], 0,
> +		if (dma_addrs[nvbe->nr_pages] != DMA_ERROR_CODE) {
> +			nvbe->pages[nvbe->nr_pages] =
> +					dma_addrs[nvbe->nr_pages];
> +		 	nvbe->ttm_alloced[nvbe->nr_pages] = true;
> +		} else {
> +			nvbe->pages[nvbe->nr_pages] =
> +				pci_map_page(dev->pdev, pages[nvbe->nr_pages], 0,
>  				     PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
> -		if (pci_dma_mapping_error(dev->pdev,
> -					  nvbe->pages[nvbe->nr_pages])) {
> -			be->func->clear(be);
> -			return -EFAULT;
> +			if (pci_dma_mapping_error(dev->pdev,
> +						  nvbe->pages[nvbe->nr_pages])) {
> +				be->func->clear(be);
> +				return -EFAULT;
> +			}
>  		}
>  
>  		nvbe->nr_pages++;
> @@ -66,11 +77,14 @@ nouveau_sgdma_clear(struct ttm_backend *be)
>  			be->func->unbind(be);
>  
>  		while (nvbe->nr_pages--) {
> -			pci_unmap_page(dev->pdev, nvbe->pages[nvbe->nr_pages],
> +			if (!nvbe->ttm_alloced[nvbe->nr_pages])
> +				pci_unmap_page(dev->pdev, nvbe->pages[nvbe->nr_pages],
>  				       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
>  		}
>  		kfree(nvbe->pages);
> +		kfree(nvbe->ttm_alloced);
>  		nvbe->pages = NULL;
> +		nvbe->ttm_alloced = NULL;
>  		nvbe->nr_pages = 0;
>  	}
>  }
> -- 
> 1.7.1
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