On Thu, 2020-07-02 at 10:18 +1000, Alexey Kardashevskiy wrote:
>
> On 02/07/2020 00:04, Leonardo Bras wrote:
> > On Wed, 2020-07-01 at 18:17 +1000, Alexey Kardashevskiy wrote:
> > > > +#define DDW_EXT_SIZE 0
> > > > +#define DDW_EXT_RESET_DMA_WIN 1
> > > > +#define DDW_EXT_QUERY_OUT_SIZE 2
> > >
> > > #define DDW_EXT_LAST (DDW_EXT_QUERY_OUT_SIZE + 1)
> > > ...
> > >
> > >
> > > > +
> > > > static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> > > > {
> > > > struct iommu_table_group *table_group;
> > > > @@ -339,7 +343,7 @@ struct direct_window {
> > > > /* Dynamic DMA Window support */
> > > > struct ddw_query_response {
> > > > u32 windows_available;
> > > > - u32 largest_available_block;
> > > > + u64 largest_available_block;
> > > > u32 page_size;
> > > > u32 migration_capable;
> > > > };
> > > > @@ -875,13 +879,29 @@ static int find_existing_ddw_windows(void)
> > > > machine_arch_initcall(pseries, find_existing_ddw_windows);
> > > >
> > > > static int query_ddw(struct pci_dev *dev, const u32 *ddw_avail,
> > > > - struct ddw_query_response *query)
> > > > + struct ddw_query_response *query,
> > > > + struct device_node *parent)
> > > > {
> > > > struct device_node *dn;
> > > > struct pci_dn *pdn;
> > > > - u32 cfg_addr;
> > > > + u32 cfg_addr, query_out[5], ddw_ext[DDW_EXT_QUERY_OUT_SIZE + 1];
> > >
> > > ... and use DDW_EXT_LAST here.
> >
> > Because of the growing nature of ddw-extensions, I intentionally let
> > this be (DDW_EXT_QUERY_OUT_SIZE + 1). If we create a DDW_EXT_LAST, it
> > will be incremented in the future if more extensions come to exist.
> >
> > I mean, I previously saw no reason for allocating space for extensions
> > after the desired one, as they won't be used here.
>
> Ah, my bad, you're right.
>
>
> > >
> > > > u64 buid;
> > > > - int ret;
> > > > + int ret, out_sz;
> > > > +
> > > > + /*
> > > > + * From LoPAR level 2.8, "ibm,ddw-extensions" index 3 can rule
> > > > how many
> > > > + * output parameters ibm,query-pe-dma-windows will have,
> > > > ranging from
> > > > + * 5 to 6.
> > > > + */
> > > > +
> > > > + ret = of_property_read_u32_array(parent, "ibm,ddw-extensions",
> > > > + &ddw_ext[0],
> > > > + DDW_EXT_QUERY_OUT_SIZE + 1);
> >
> > In this case, I made sure not to cross (DDW_EXT_QUERY_OUT_SIZE + 1)
> > while reading the extensions from the property.
> >
> > What do you think about it?
>
> I think you want something like:
>
> static inline int ddw_read_ext(const struct device_node *np, int extnum,
> u32 *ret)
> {
> retun of_property_read_u32_index(np, "ibm,ddw-extensions", extnum + 1, ret);
> }
>
> These "+1"'s all over the place are confusing.
That's a great idea!
I was not aware it was possible to read a single value[index] directly
from the property, but it makes total sense to use it.
Thank you!
