Re: [PATCH 6/6] dma-mapping: introduce DMA range map, supplanting dma_pfn_offset

Hi Christoph, Jim,

On Wed, Sep 16, 2020 at 8:30 AM Christoph Hellwig [off-list ref] wrote:

From: Jim Quinlan <redacted>

The new field 'dma_range_map' in struct device is used to facilitate the
use of single or multiple offsets between mapping regions of cpu addrs and
dma addrs.  It subsumes the role of "dev->dma_pfn_offset" which was only
capable of holding a single uniform offset and had no region bounds
checking.

The function of_dma_get_range() has been modified so that it takes a single
argument -- the device node -- and returns a map, NULL, or an error code.
The map is an array that holds the information regarding the DMA regions.
Each range entry contains the address offset, the cpu_start address, the
dma_start address, and the size of the region.

of_dma_configure() is the typical manner to set range offsets but there are
a number of ad hoc assignments to "dev->dma_pfn_offset" in the kernel
driver code.  These cases now invoke the function
dma_direct_set_offset(dev, cpu_addr, dma_addr, size).

Signed-off-by: Jim Quinlan <redacted>
[hch: various interface cleanups]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Nathan Chancellor <redacted>

Thanks for your patch, which is now commit e0d072782c734d27
("dma-mapping: introduce DMA range map, supplanting dma_pfn_offset") in
v5.10-rc1, and to which I have bisected a PCIe failure on R-Car M2-W
(r8a7791/koelsch).

The first PCI host bridge, containing USB, probes fine:

 pci-rcar-gen2 ee090000.pci: host bridge /soc/pci@ee090000 ranges:
 pci-rcar-gen2 ee090000.pci:      MEM 0x00ee080000..0x00ee08ffff -> 0x00ee080000
 pci-rcar-gen2 ee090000.pci: PCI: revision 11
 pci-rcar-gen2 ee090000.pci: PCI host bridge to bus 0000:00
 pci_bus 0000:00: root bus resource [bus 00]
 pci_bus 0000:00: root bus resource [mem 0xee080000-0xee08ffff]
 pci 0000:00:00.0: [1033:0000] type 00 class 0x060000
 pci 0000:00:00.0: reg 0x10: [mem 0xee090800-0xee090bff]
 pci 0000:00:00.0: reg 0x14: [mem 0x40000000-0x7fffffff pref]
 pci 0000:00:01.0: [1033:0035] type 00 class 0x0c0310
 pci 0000:00:01.0: reg 0x10: [mem 0x00000000-0x00000fff]
 pci 0000:00:01.0: supports D1 D2
 pci 0000:00:01.0: PME# supported from D0 D1 D2 D3hot
 pci 0000:00:02.0: [1033:00e0] type 00 class 0x0c0320
 pci 0000:00:02.0: reg 0x10: [mem 0x00000000-0x000000ff]
 pci 0000:00:02.0: supports D1 D2
 pci 0000:00:02.0: PME# supported from D0 D1 D2 D3hot
 PCI: bus0: Fast back to back transfers disabled
 pci 0000:00:01.0: BAR 0: assigned [mem 0xee080000-0xee080fff]
 pci 0000:00:02.0: BAR 0: assigned [mem 0xee081000-0xee0810ff]
 pci 0000:00:01.0: enabling device (0140 -> 0142)
 pci 0000:00:02.0: enabling device (0140 -> 0142)

The second PCI host bridge, connected to an (empty) PCIe slot, fails:

 pci-rcar-gen2 ee0d0000.pci: host bridge /soc/pci@ee0d0000 ranges:
 pci-rcar-gen2 ee0d0000.pci:      MEM 0x00ee0c0000..0x00ee0cffff -> 0x00ee0c0000
 pci-rcar-gen2 ee0d0000.pci: PCI: revision 11
 pci-rcar-gen2 ee0d0000.pci: PCI host bridge to bus 0001:01
 pci_bus 0001:01: root bus resource [bus 01]
 pci_bus 0001:01: root bus resource [mem 0xee0c0000-0xee0cffff]
 pci 0001:01:00.0: [1033:0000] type 00 class 0x060000
 pci 0001:01:00.0: reg 0x10: [mem 0xee0d0800-0xee0d0bff]
 pci 0001:01:00.0: reg 0x14: [mem 0x40000000-0x7fffffff pref]
 pci 0001:01:01.0: [1033:0035] type 00 class 0x0c0310
 pci 0001:01:01.0: reg 0x10: [mem 0x00000000-0x00000fff]
 pci 0001:01:01.0: supports D1 D2
 pci 0001:01:01.0: PME# supported from D0 D1 D2 D3hot
 pci 0001:01:02.0: [1033:00e0] type 00 class 0x0c0320
 pci 0001:01:02.0: reg 0x10: [mem 0x00000000-0x000000ff]
 pci 0001:01:02.0: supports D1 D2
 pci 0001:01:02.0: PME# supported from D0 D1 D2 D3hot
 PCI: bus1: Fast back to back transfers disabled
 pci 0001:01:01.0: BAR 0: assigned [mem 0xee0c0000-0xee0c0fff]
 pci 0001:01:02.0: BAR 0: assigned [mem 0xee0c1000-0xee0c10ff]
 pci 0001:01:01.0: enabling device (0140 -> 0142)
 pci 0001:01:02.0: enabling device (0140 -> 0142)
-rcar-pcie fe000000.pcie: host bridge /soc/pcie@fe000000 ranges:
-rcar-pcie fe000000.pcie:       IO 0x00fe100000..0x00fe1fffff -> 0x0000000000
-rcar-pcie fe000000.pcie:      MEM 0x00fe200000..0x00fe3fffff -> 0x00fe200000
-rcar-pcie fe000000.pcie:      MEM 0x0030000000..0x0037ffffff -> 0x0030000000
-rcar-pcie fe000000.pcie:      MEM 0x0038000000..0x003fffffff -> 0x0038000000
-rcar-pcie fe000000.pcie:   IB MEM 0x0040000000..0x00bfffffff -> 0x0040000000
-rcar-pcie fe000000.pcie:   IB MEM 0x0200000000..0x02ffffffff -> 0x0200000000
-rcar-pcie fe000000.pcie: PCIe link down
+rcar-pcie fe000000.pcie: Adjusted size 0x0 invalid
+rcar-pcie: probe of fe000000.pcie failed with error -22

I've posted a patch "[PATCH] dma-mapping: Fix 32-bit overflow with
CONFIG_ARM_LPAE=n"
(https://lore.kernel.org/linux-arm-kernel/20201026152755.3738293-1-geert+renesas@glider.be/ (local)).

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds