Hi Ben,
Please don't take this patch :)
While, it does work around some issues I'm tracking down, it can lead
to worse ones if we are unable to configure the larger DMA window, or if
some functions in a PE don't use 64-bit DMA masks.
Thanks,
Nish
On 26.10.2011 [15:43:23 -0700], Nishanth Aravamudan wrote:
> The DDW feature relies on there being sufficient TCE space to allocate
> for the requested DMA window size. The default window uses up some of
> that space, though, and it is recommended to first remove the default
> window and then allocate the larger window advertised by firmware. Do
> this by abstracting out parts of remove_ddw into a function that does
> not assume an existing larger window has been created.
>
> Signed-off-by: Nishanth Aravamudan
> ---
> arch/powerpc/platforms/pseries/iommu.c | 35 +++
> 1 files changed, 26 insertions(+), 9 deletions(-)
>
> Is there a better way to get the default window's LIOBN than to call
> of_parse_dma_window?
>
> diff --git a/arch/powerpc/platforms/pseries/iommu.c
> b/arch/powerpc/platforms/pseries/iommu.c
> index 01faab9..afcc04c 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -655,6 +655,21 @@ static int __init disable_ddw_setup(char *str)
>
> early_param("disable_ddw", disable_ddw_setup);
>
> +static void __remove_ddw(struct device_node *np, const u32 *ddw_avail, u64
> liobn)
> +{
> + int ret;
> +
> + ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
> + if (ret)
> + pr_warning("%s: failed to remove direct window: rtas returned "
> + "%d to ibm,remove-pe-dma-window(%x) %llx\n",
> + np->full_name, ret, ddw_avail[2], liobn);
> + else
> + pr_debug("%s: successfully removed direct window: rtas returned
> "
> + "%d to ibm,remove-pe-dma-window(%x) %llx\n",
> + np->full_name, ret, ddw_avail[2], liobn);
> +}
> +
> static void remove_ddw(struct device_node *np)
> {
> struct dynamic_dma_window_prop *dwp;
> @@ -684,15 +699,7 @@ static void remove_ddw(struct device_node *np)
> pr_debug("%s successfully cleared tces in window.\n",
>np->full_name);
>
> - ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
> - if (ret)
> - pr_warning("%s: failed to remove direct window: rtas returned "
> - "%d to ibm,remove-pe-dma-window(%x) %llx\n",
> - np->full_name, ret, ddw_avail[2], liobn);
> - else
> - pr_debug("%s: successfully removed direct window: rtas returned
> "
> - "%d to ibm,remove-pe-dma-window(%x) %llx\n",
> - np->full_name, ret, ddw_avail[2], liobn);
> + __remove_ddw(np, ddw_avail, liobn);
>
> delprop:
> ret = prom_remove_property(np, win64);
> @@ -843,6 +850,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct
> device_node *pdn)
> struct direct_window *window;
> struct property *win64;
> struct dynamic_dma_window_prop *ddwprop;
> + const void *dma_window = NULL;
> + unsigned long liobn, offset, size;
>
> mutex_lock(&direct_window_init_mutex);
>
> @@ -918,6 +927,14 @@ static u64 enable_ddw(struct pci_dev *dev, struct
> device_node *pdn)
> goto out_free_prop;
> }
>
> + /*
> + * To maximize the resources available to the create RTAS call,
> + * delete the existing DMA window
> + */
> + dma_window = of_get_property(pdn, "ibm,dma-window", NULL);
> + of_parse_dma_window(pdn, dma_window, &liobn, &offset, &size);
> + __remove_ddw(pdn, ddw_avail, liobn);
> +
> ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
> if (ret != 0)
> goto out_free_prop;
> --
> 1.7.5.4
>
>
> --
> Nishanth Aravamudan
> IBM Linux Technology Center
--
Nishanth Aravamudan
IBM Linux Technology Center
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