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

From: Gavin Shan <[email-masked]>
Date: Tue, 17 Nov 2015 20:06:53 +1100

On Tue, Nov 17, 2015 at 05:04:42PM +1100, Alexey Kardashevskiy wrote:
>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.
>

Please confirm if it's fine to add the descrption in this patch's chagelog.

>
>>
>>Signed-off-by: Gavin Shan <[email-masked]>
>>---
>>  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;
>>

Thanks,
Gavin