Re: [PATCH] agp: use scratch page on memory remove and at GATT creation V2

["Ville Syrjälä" <syrjala@sci.fi>]

On Tue, Apr 20, 2010 at 02:31:52PM +0200, glisse@freedesktop.org wrote:
> From: Jerome Glisse <jglisse@redhat.com>
> 
> Convert most AGP chipset to use scratch page as default entries.
> This help avoiding GPU querying 0 address and trigger computer
> fault. With KMS and memory manager we bind/unbind AGP memory
> constantly and it seems that some GPU are still doing AGP
> traffic even after GPU report being idle with the memory segment.
> 
> Tested (radeon GPU KMS + Xorg + compiz + glxgears + quake3) on :
> - SIS 1039:0001 & 1039:0003
> - Intel 865 8086:2571
> 
> Compile tested for other bridges
> 
> V2 enable scratch page on uninorth
> 
> Signed-off-by: Jerome Glisse <jglisse@redhat.com>
<snip>
> diff --git a/drivers/char/agp/amd-k7-agp.c b/drivers/char/agp/amd-k7-agp.c
> index 73dbf40..cf4dc4c 100644
> --- a/drivers/char/agp/amd-k7-agp.c
> +++ b/drivers/char/agp/amd-k7-agp.c
> @@ -178,6 +179,13 @@ static int amd_create_gatt_table(struct agp_bridge_data *bridge)
>  		readl(page_dir.remapped+GET_PAGE_DIR_OFF(addr));	/* PCI Posting. */
>  	}
>  
> +	for (i = 0; i < value->num_entries; i++) {
> +		addr = (i * PAGE_SIZE) + agp_bridge->gart_bus_addr;
> +		cur_gatt = GET_GATT(addr);
> +		writel(agp_bridge->scratch_page, cur_gatt+GET_GATT_OFF(addr));
> +		readl(cur_gatt+GET_GATT_OFF(addr));	/* PCI Posting. */
> +	}

Isn't it enough to do a single PCI posting flush after writing all the
entries?

-- 
Ville Syrjälä
syrjala@sci.fi
http://www.sci.fi/~syrjala/