Re: [PATCH v7 25/50] powerpc/powernv: Reserve PE for root bus

Alexey Kardashevskiy
2015-11-17T06:04:50Z

On 11/05/2015 12:12 AM, Gavin Shan wrote:
> We're going to reserve/assign PEs when pcibios_setup_bridge() is
> called. The function won't be called for root bus as it doesn't
> have parent bridge. However, the root bus still needs a PE to be
> covered.
>
> This reserves PE numbers that are adjacent to the reserved one
> for root buses.

Somewhere in the patchset you need to describe why you need a separate PE
for a root bus and why reserved_pe_idx is not enough for this.

>
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
> ---
> arch/powerpc/platforms/powernv/pci-ioda.c | 33 ++++++++++++++++++++++---------
> arch/powerpc/platforms/powernv/pci.h | 1 +
> 2 files changed, 25 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index eea1c96..5e6745f 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -207,14 +207,14 @@ static int pnv_ioda2_init_m64(struct pnv_phb *phb)
> set_bit(phb->ioda.m64_bar_idx, &phb->ioda.m64_bar_alloc);
>
> /*
> - * Strip off the segment used by the reserved PE, which is
> - * expected to be 0 or last one of PE capabicity.
> + * Exclude the segments for reserved and root bus PE, which
> + * are first or last two PEs.
> */
> r = &phb->hose->mem_resources[1];
> if (phb->ioda.reserved_pe_idx == 0)
> - r->start += phb->ioda.m64_segsize;
> + r->start += (2 * phb->ioda.m64_segsize);
> else if (phb->ioda.reserved_pe_idx == (phb->ioda.total_pe_num - 1))
> - r->end -= phb->ioda.m64_segsize;
> + r->end -= (2 * phb->ioda.m64_segsize);
> else
> pr_warn(" Cannot strip M64 segment for reserved PE#%d\n",
> phb->ioda.reserved_pe_idx);
> @@ -294,14 +294,14 @@ static int pnv_ioda1_init_m64(struct pnv_phb *phb)
> }
>
> /*
> - * Exclude the segment used by the reserved PE, which
> - * is expected to be 0 or last supported PE#.
> + * Exclude the segments for reserved and root bus PE, which
> + * are first or last two PEs.
> */
> r = &phb->hose->mem_resources[1];
> if (phb->ioda.reserved_pe_idx == 0)
> - r->start += phb->ioda.m64_segsize;
> + r->start += (2 * phb->ioda.m64_segsize);
> else if (phb->ioda.reserved_pe_idx == (phb->ioda.total_pe_num - 1))
> - r->end -= phb->ioda.m64_segsize;
> + r->end -= (2 * phb->ioda.m64_segsize);
> else
> pr_warn(" Cannot cut M64 segment for reserved PE#%d\n",
> phb->ioda.reserved_pe_idx);
> @@ -3231,7 +3231,22 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
> phb->ioda.dma32_segmap[i] = IODA_INVALID_PE;
> }
> phb->ioda.pe_array = aux + pemap_off;
> - set_bit(phb->ioda.reserved_pe_idx, phb->ioda.pe_alloc);
> +
> + /*
> + * Choose PE number for root bus, which shouldn't have
> + * M64 resources consumed by its child devices. To pick
> + * the PE number adjacent to the reserved one if possible.
> + */
> + pnv_ioda_reserve_pe(phb, phb->ioda.reserved_pe_idx);
> + if (phb->ioda.reserved_pe_idx == 0) {
> + phb->ioda.root_pe_idx = 1;
> + pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
> + } else if (phb->ioda.reserved_pe_idx == (phb->ioda.total_pe_num - 1)) {
> + phb->ioda.root_pe_idx = phb->ioda.reserved_pe_idx - 1;
> + pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
> + } else {
> + phb->ioda.root_pe_idx = IODA_INVALID_PE;
> + }
>
> INIT_LIST_HEAD(&phb->ioda.pe_list);
> mutex_init(&phb->ioda.pe_list_mutex);
> diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
> index e55ab0e..a8ba97f 100644
> --- a/arch/powerpc/platforms/powernv/pci.h
> +++ b/arch/powerpc/platforms/powernv/pci.h
> @@ -120,6 +120,7 @@ struct pnv_phb {
> /* Global bridge info */
> unsigned int total_pe_num;
> unsigned int reserved_pe_idx;
> + unsigned int root_pe_idx;
>
> /* 32-bit MMIO window */
> unsigned int m32_size;
>

--
Alexey