Subject: Re: [PATCH v7 18/50] powerpc/powernv: Remove DMA32 PE list

From: Alexey Kardashevskiy <[email-masked]>
Date: Tue, 17 Nov 2015 12:54:04 +1100

On 11/05/2015 12:12 AM, Gavin Shan wrote:
> PEs are put into PHB DMA32 list (phb->ioda.pe_dma_list) according
> to their DMA32 weight. The PEs on the list are iterated to setup
> their TCE32 tables at system booting time. The list is used for
> once and there is no good reason for it to survive.

 From the above I concluded that you need a list, just do not need to keep 
after the configuration is done but in fact you remove the list completely 
so just remove "to survive" (s/for it to survive/for keep having it/) :)

>
> This moves the logic calculating DMA32 weight of PHB and PE to
> pnv_pci_ioda1_setup_dma() to drop PHB's DMA32 list.
>
> Signed-off-by: Gavin Shan <[email-masked]>
> ---
>   arch/powerpc/platforms/powernv/pci-ioda.c | 150 ++++++++++++++----------------
>   arch/powerpc/platforms/powernv/pci.h      |  19 ----
>   2 files changed, 68 insertions(+), 101 deletions(-)
>
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 4c2e023..20ebe6e 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -891,44 +891,6 @@ out:
>   	return 0;
>   }
>
> -static void pnv_ioda_link_pe_by_weight(struct pnv_phb *phb,
> -				       struct pnv_ioda_pe *pe)
> -{
> -	struct pnv_ioda_pe *lpe;
> -
> -	list_for_each_entry(lpe, &phb->ioda.pe_dma_list, dma_link) {
> -		if (lpe->dma_weight < pe->dma_weight) {
> -			list_add_tail(&pe->dma_link, &lpe->dma_link);
> -			return;
> -		}
> -	}
> -	list_add_tail(&pe->dma_link, &phb->ioda.pe_dma_list);
> -}
> -
> -static unsigned int pnv_ioda_dma_weight(struct pci_dev *dev)
> -{
> -	/* This is quite simplistic. The "base" weight of a device
> -	 * is 10. 0 means no DMA is to be accounted for it.
> -	 */
> -
> -	/* If it's a bridge, no DMA */
> -	if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
> -		return 0;
> -
> -	/* Reduce the weight of slow USB controllers */
> -	if (dev->class == PCI_CLASS_SERIAL_USB_UHCI ||
> -	    dev->class == PCI_CLASS_SERIAL_USB_OHCI ||
> -	    dev->class == PCI_CLASS_SERIAL_USB_EHCI)
> -		return 3;
> -
> -	/* Increase the weight of RAID (includes Obsidian) */
> -	if ((dev->class >> 8) == PCI_CLASS_STORAGE_RAID)
> -		return 15;
> -
> -	/* Default */
> -	return 10;
> -}
> -
>   #ifdef CONFIG_PCI_IOV
>   static int pnv_pci_vf_resource_shift(struct pci_dev *dev, int offset)
>   {
> @@ -1009,7 +971,6 @@ static void pnv_ioda_setup_same_PE(struct pci_bus *bus, struct pnv_ioda_pe *pe)
>   			continue;
>   		}
>   		pdn->pe_number = pe->pe_number;
> -		pe->dma_weight += pnv_ioda_dma_weight(dev);
>   		if ((pe->flags & PNV_IODA_PE_BUS_ALL) && dev->subordinate)
>   			pnv_ioda_setup_same_PE(dev->subordinate, pe);
>   	}
> @@ -1046,10 +1007,8 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>   	pe->flags |= (all ? PNV_IODA_PE_BUS_ALL : PNV_IODA_PE_BUS);
>   	pe->pbus = bus;
>   	pe->pdev = NULL;
> -	pe->tce32_seg = -1;
>   	pe->mve_number = -1;
>   	pe->rid = bus->busn_res.start << 8;
> -	pe->dma_weight = 0;
>
>   	if (all)
>   		pe_info(pe, "Secondary bus %d..%d associated with PE#%d\n",
> @@ -1071,17 +1030,6 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, bool all)
>
>   	/* Put PE to the list */
>   	list_add_tail(&pe->list, &phb->ioda.pe_list);
> -
> -	/* Account for one DMA PE if at least one DMA capable device exist
> -	 * below the bridge
> -	 */
> -	if (pe->dma_weight != 0) {
> -		phb->ioda.dma_weight += pe->dma_weight;
> -		phb->ioda.dma_pe_count++;
> -	}
> -
> -	/* Link the PE */
> -	pnv_ioda_link_pe_by_weight(phb, pe);
>   }
>
>   static void pnv_ioda_setup_PEs(struct pci_bus *bus)
> @@ -1389,7 +1337,6 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
>   		pe->flags = PNV_IODA_PE_VF;
>   		pe->pbus = NULL;
>   		pe->parent_dev = pdev;
> -		pe->tce32_seg = -1;
>   		pe->mve_number = -1;
>   		pe->rid = (pci_iov_virtfn_bus(pdev, vf_index) << 8) |
>   			   pci_iov_virtfn_devfn(pdev, vf_index);
> @@ -1842,6 +1789,47 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = {
>   	.free = pnv_ioda2_table_free,
>   };
>
> +static int pnv_pci_ioda_dev_dma_weight(struct pci_dev *dev, void *data)
> +{
> +	unsigned int *weight = (unsigned int *)data;
> +
> +	/* This is quite simplistic. The "base" weight of a device
> +	 * is 10. 0 means no DMA is to be accounted for it.
> +	 */
> +
> +	if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL)
> +		return 0;
> +
> +	if (dev->class == PCI_CLASS_SERIAL_USB_UHCI ||
> +	    dev->class == PCI_CLASS_SERIAL_USB_OHCI ||
> +	    dev->class == PCI_CLASS_SERIAL_USB_EHCI)
> +		*weight += 3;
> +	else if ((dev->class >> 8) == PCI_CLASS_STORAGE_RAID)
> +		*weight += 15;
> +	else
> +		*weight += 10;
> +
> +	return 0;
> +}
> +
> +static unsigned int pnv_pci_ioda_pe_dma_weight(struct pnv_ioda_pe *pe)
> +{
> +	unsigned int weight = 0;
> +
> +	if ((pe->flags & PNV_IODA_PE_DEV) && pe->pdev) {
> +		pnv_pci_ioda_dev_dma_weight(pe->pdev, &weight);
> +	} else if ((pe->flags & PNV_IODA_PE_BUS) && pe->pbus) {
> +		struct pci_dev *pdev;
> +
> +		list_for_each_entry(pdev, &pe->pbus->devices, bus_list)
> +			pnv_pci_ioda_dev_dma_weight(pdev, &weight);
> +	} else if ((pe->flags & PNV_IODA_PE_BUS_ALL) && pe->pbus) {
> +		pci_walk_bus(pe->pbus, pnv_pci_ioda_dev_dma_weight, &weight);
> +	}
> +
> +	return weight;
> +}
> +
>   static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
>   				       struct pnv_ioda_pe *pe,
>   				       unsigned int base,
> @@ -1858,17 +1846,12 @@ static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
>   	/* XXX FIXME: Provide 64-bit DMA facilities & non-4K TCE tables etc.. */
>   	/* XXX FIXME: Allocate multi-level tables on PHB3 */
>
> -	/* We shouldn't already have a 32-bit DMA associated */
> -	if (WARN_ON(pe->tce32_seg >= 0))
> -		return;
> -
>   	tbl = pnv_pci_table_alloc(phb->hose->node);
>   	iommu_register_group(&pe->table_group, phb->hose->global_number,
>   			pe->pe_number);
>   	pnv_pci_link_table_and_group(phb->hose->node, 0, tbl, &pe->table_group);
>
>   	/* Grab a 32-bit TCE table */
> -	pe->tce32_seg = base;
>   	pe_info(pe, " Setting up 32-bit TCE table at %08x..%08x\n",
>   		base * PNV_IODA1_DMA32_SEGSIZE,
>   		(base + segs) * PNV_IODA1_DMA32_SEGSIZE - 1);
> @@ -1932,8 +1915,6 @@ static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
>   	return;
>    fail:
>   	/* XXX Failure: Try to fallback to 64-bit only ? */
> -	if (pe->tce32_seg >= 0)
> -		pe->tce32_seg = -1;
>   	if (tce_mem)
>   		__free_pages(tce_mem, get_order(tce32_segsz * segs));
>   	if (tbl) {
> @@ -2344,10 +2325,6 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>   {
>   	int64_t rc;
>
> -	/* We shouldn't already have a 32-bit DMA associated */
> -	if (WARN_ON(pe->tce32_seg >= 0))
> -		return;
> -
>   	/* TVE #1 is selected by PCI address bit 59 */
>   	pe->tce_bypass_base = 1ull << 59;
>
> @@ -2355,7 +2332,6 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>   			pe->pe_number);
>
>   	/* The PE will reserve all possible 32-bits space */
> -	pe->tce32_seg = 0;
>   	pe_info(pe, "Setting up 32-bit TCE table at 0..%08x\n",
>   		phb->ioda.m32_pci_base);
>
> @@ -2371,11 +2347,8 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>   #endif
>
>   	rc = pnv_pci_ioda2_setup_default_config(pe);
> -	if (rc) {
> -		if (pe->tce32_seg >= 0)
> -			pe->tce32_seg = -1;
> +	if (rc)
>   		return;
> -	}
>
>   	if (pe->flags & PNV_IODA_PE_DEV)
>   		iommu_add_device(&pe->pdev->dev);
> @@ -2386,24 +2359,34 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
>   static void pnv_pci_ioda1_setup_dma(struct pnv_phb *phb)
>   {
>   	struct pci_controller *hose = phb->hose;
> -	unsigned int residual, remaining, segs, tw, base;
> +	unsigned int weight, total_weight, dma_pe_count;
> +	unsigned int residual, remaining, segs, base;
>   	struct pnv_ioda_pe *pe;
>
> +	total_weight = 0;
> +	dma_pe_count = 0;
> +	list_for_each_entry(pe, &phb->ioda.pe_list, list) {
> +		weight = pnv_pci_ioda_pe_dma_weight(pe);
> +		if (weight > 0)
> +			dma_pe_count++;
> +
> +		total_weight += weight;
> +	}
> +
>   	/* If we have more PE# than segments available, hand out one
>   	 * per PE until we run out and let the rest fail. If not,
>   	 * then we assign at least one segment per PE, plus more based
>   	 * on the amount of devices under that PE
>   	 */
> -	if (phb->ioda.dma_pe_count > phb->ioda.tce32_count)
> +	if (dma_pe_count > phb->ioda.tce32_count)
>   		residual = 0;
>   	else
> -		residual = phb->ioda.tce32_count -
> -			phb->ioda.dma_pe_count;
> +		residual = phb->ioda.tce32_count - dma_pe_count;
>
>   	pr_info("PCI: Domain %04x has %ld available 32-bit DMA segments\n",
>   		hose->global_number, phb->ioda.tce32_count);
>   	pr_info("PCI: %d PE# for a total weight of %d\n",
> -		phb->ioda.dma_pe_count, phb->ioda.dma_weight);
> +		dma_pe_count, total_weight);
>
>   	pnv_pci_ioda_setup_opal_tce_kill(phb);
>
> @@ -2412,24 +2395,26 @@ static void pnv_pci_ioda1_setup_dma(struct pnv_phb *phb)
>   	 * weight
>   	 */
>   	remaining = phb->ioda.tce32_count;
> -	tw = phb->ioda.dma_weight;
>   	base = 0;
> -	list_for_each_entry(pe, &phb->ioda.pe_dma_list, dma_link) {
> -		if (!pe->dma_weight)
> +	list_for_each_entry(pe, &phb->ioda.pe_list, list) {
> +		weight = pnv_pci_ioda_pe_dma_weight(pe);
> +		if (!weight)
>   			continue;
> +

Unrelated new line.

-- 
Alexey