Commit fe7e85c6 authored by Gavin Shan's avatar Gavin Shan Committed by Michael Ellerman
Browse files

powerpc/powernv: Override dma_get_required_mask() 



The dma_get_required_mask() function is used by some drivers to
query the platform about what DMA mask is needed to cover all of
memory. This is a bit of a strange semantic when we have to choose
between IOMMU translation or bypass, but essentially what it means
is "what DMA mask will give best performances".

Currently, our IOMMU backend always returns a 32-bit mask here, we
don't do anything special to it when we have bypass available. This
causes some drivers to choose a 32-bit mask, thus losing the ability
to use the bypass window, thinking this is more efficient. The problem
was reported from the driver of following device:

0004:03:00.0 0107: 1000:0087 (rev 05)
0004:03:00.0 Serial Attached SCSI controller: LSI Logic / Symbios \
             Logic SAS2308 PCI-Express Fusion-MPT SAS-2 (rev 05)

This patch adds an override of that function in order to, instead,
return a 64-bit mask whenever a bypass window is available in order
for drivers to prefer this configuration.

Reported-by: default avatarMurali N. Iyer <mniyer@us.ibm.com>
Suggested-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarGavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 372fb80d

arch/powerpc/include/asm/dma-mapping.h

+1 −0
Original line number Diff line number Diff line
@@ -135,6 +135,7 @@ static inline int dma_supported(struct device *dev, u64 mask) 


extern int dma_set_mask(struct device *dev, u64 dma_mask);

extern int __dma_set_mask(struct device *dev, u64 dma_mask);

extern u64 __dma_get_required_mask(struct device *dev);



#define dma_alloc_coherent(d,s,h,f)	dma_alloc_attrs(d,s,h,f,NULL)

arch/powerpc/kernel/dma.c

+10 −4
Original line number Diff line number Diff line
@@ -202,6 +202,7 @@ int __dma_set_mask(struct device *dev, u64 dma_mask) 
	*dev->dma_mask = dma_mask;

	return 0;

}



int dma_set_mask(struct device *dev, u64 dma_mask)

{

	if (ppc_md.dma_set_mask)
@@ -210,13 +211,10 @@ int dma_set_mask(struct device *dev, u64 dma_mask) 
}

EXPORT_SYMBOL(dma_set_mask);



u64 dma_get_required_mask(struct device *dev)

u64 __dma_get_required_mask(struct device *dev)

{

	struct dma_map_ops *dma_ops = get_dma_ops(dev);



	if (ppc_md.dma_get_required_mask)

		return ppc_md.dma_get_required_mask(dev);



	if (unlikely(dma_ops == NULL))

		return 0;
@@ -225,6 +223,14 @@ u64 dma_get_required_mask(struct device *dev) 


	return DMA_BIT_MASK(8 * sizeof(dma_addr_t));

}



u64 dma_get_required_mask(struct device *dev)

{

	if (ppc_md.dma_get_required_mask)

		return ppc_md.dma_get_required_mask(dev);



	return __dma_get_required_mask(dev);

}

EXPORT_SYMBOL_GPL(dma_get_required_mask);



static int __init dma_init(void)

arch/powerpc/platforms/powernv/pci-ioda.c

+23 −0
Original line number Diff line number Diff line
@@ -889,6 +889,28 @@ static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb, 
	return 0;

}



static u64 pnv_pci_ioda_dma_get_required_mask(struct pnv_phb *phb,

					      struct pci_dev *pdev)

{

	struct pci_dn *pdn = pci_get_pdn(pdev);

	struct pnv_ioda_pe *pe;

	u64 end, mask;



	if (WARN_ON(!pdn || pdn->pe_number == IODA_INVALID_PE))

		return 0;



	pe = &phb->ioda.pe_array[pdn->pe_number];

	if (!pe->tce_bypass_enabled)

		return __dma_get_required_mask(&pdev->dev);





	end = pe->tce_bypass_base + memblock_end_of_DRAM();

	mask = 1ULL << (fls64(end) - 1);

	mask += mask - 1;



	return mask;

}



static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe,

				   struct pci_bus *bus,

				   bool add_to_iommu_group)
@@ -1781,6 +1803,7 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np, 
	/* Setup TCEs */

	phb->dma_dev_setup = pnv_pci_ioda_dma_dev_setup;

	phb->dma_set_mask = pnv_pci_ioda_dma_set_mask;

	phb->dma_get_required_mask = pnv_pci_ioda_dma_get_required_mask;



	/* Setup shutdown function for kexec */

	phb->shutdown = pnv_pci_ioda_shutdown;

arch/powerpc/platforms/powernv/pci.c

+11 −0
Original line number Diff line number Diff line
@@ -761,6 +761,17 @@ int pnv_pci_dma_set_mask(struct pci_dev *pdev, u64 dma_mask) 
	return __dma_set_mask(&pdev->dev, dma_mask);

}



u64 pnv_pci_dma_get_required_mask(struct pci_dev *pdev)

{

	struct pci_controller *hose = pci_bus_to_host(pdev->bus);

	struct pnv_phb *phb = hose->private_data;



	if (phb && phb->dma_get_required_mask)

		return phb->dma_get_required_mask(phb, pdev);



	return __dma_get_required_mask(&pdev->dev);

}



void pnv_pci_shutdown(void)

{

	struct pci_controller *hose;

arch/powerpc/platforms/powernv/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -124,6 +124,8 @@ struct pnv_phb { 
	void (*dma_dev_setup)(struct pnv_phb *phb, struct pci_dev *pdev);

	int (*dma_set_mask)(struct pnv_phb *phb, struct pci_dev *pdev,

			    u64 dma_mask);

	u64 (*dma_get_required_mask)(struct pnv_phb *phb,

				     struct pci_dev *pdev);

	void (*fixup_phb)(struct pci_controller *hose);

	u32 (*bdfn_to_pe)(struct pnv_phb *phb, struct pci_bus *bus, u32 devfn);

	void (*shutdown)(struct pnv_phb *phb);

CRA Git | Maintained and supported by SUSTech CRA and CCSE