Re: [PATCH 1/2] MIPS: SiByte: Set 32-bit bus mask for BCM1250 PCI

From: Christoph Hellwig
Date: Wed Nov 07 2018 - 02:59:12 EST

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In reply to: Maciej W. Rozycki: "[PATCH 1/2] MIPS: SiByte: Set 32-bit bus mask for BCM1250 PCI"
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On Wed, Nov 07, 2018 at 12:08:23AM +0000, Maciej W. Rozycki wrote:
> The Broadcom SiByte BCM1250, BCM1125H and BCM1125 SOCs have an onchip
> 32-bit PCI host bridge, and the two former SOCs also have an onchip HT
> host bridge. The HT host bridge, where present, appears in the PCI
> configuration space as if it was a device on the 32-bit PCI bus behind
> the PCI host bridge, however at the hardware level its signals are
> routed separately, so these two devices are actually peer host bridges.
>
> As documented[1] and observed in reality the 32-bit PCI host bridge does
> not support 64-bit addressing as it does not support the Dual Address
> Cycle (DAC) PCI command, and naturally, being 32-bit only, it has no
> means to carry the high 32 address bits otherwise. However the DRAM
> controller also included in the SOC supports memory amounts of up to
> 16GiB, and due to how the address decoder has been wired in the SOC any
> memory beyond 1GiB is actually mapped starting from 4GiB physical up,
> that is beyond the 32-bit addressable limit. Consequently if the
> maximum amount of memory has been installed, then it will span up to
> 19GiB.
>
> Contrariwise, the HT host bridge does support full 40-bit addressing
> defined by the HyperTransport (formerly LDT) specification the bridge
> adheres to, depending on the peripherals revision of the SOC[2] either
> revision 0.17[3] or revision 1.03[4]. This allows addressing any and
> all memory installed, and well beyond.
>
> Set the bus mask then to limit DMA addressing to 32 bits for all the
> devices down the 32-bit PCI host bridge, excluding however any devices
> that are down the HT host bridge.
>
> References:
>
> [1] "BCM1250/BCM1125/BCM1125H User Manual", Revision 1250_1125-UM100-R,
> Broadcom Corporation, 21 Oct 2002, Section 8: "PCI Bus and
> HyperTransport Fabric", "Introduction", p. 190
>
> [2] same, Table 140: "HyperTransport Configuration Header (Type 1)", p.
> 245
>
> [3] "Lightning Data Transport IO Specification", Revision 0.17, Advanced
> Micro Devices, 21 Jan 2000, Section 3.2.1.2 "Command Packet", p. 8
>
> [4] "HyperTransport I/O Link Specification", Revision 1.03,
> HyperTransport Technology Consortium, 10 Oct 2001, Section 3.2.1.2
> "Request Packet", pp. 27-28
>
> Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
> ---
> Hi,
>
> This has been verified with a Broadcom SWARM board and an XHCI USB 32-bit
> PCI option board plugged to one of the mainboard's 32-bit slots wired to
> the PCI host bridge, and then a flash storage device plugged to adapter's
> USB socket.
>
> With 2/2 applied first so that the bus mask is respected and a diagnostic
> patch for `dma_direct_alloc' made to debug an earlier issue also applied
> the system shows these messages upon boot:
>
> xhci_hcd 0000:03:00.0: assign IRQ: got 56
> xhci_hcd 0000:03:00.0: enabling bus mastering
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b48000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b4c000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b54000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b58000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b5c000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b60000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b64000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b68000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b6c000
> xhci_hcd 0000:03:00.0: hcc params 0x014051c7 hci version 0x100 quirks 0x0000000100000090
> xhci_hcd 0000:03:00.0: enabling Mem-Wr-Inval
> usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19
> usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> usb usb1: Product: xHCI Host Controller
> usb usb1: Manufacturer: Linux 4.19.0 xhci-hcd
> usb usb1: SerialNumber: 0000:03:00.0
> hub 1-0:1.0: USB hub found
> hub 1-0:1.0: 2 ports detected
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 2
> xhci_hcd 0000:03:00.0: Host supports USB 3.0 SuperSpeed
> xhci_hcd 0000:03:00.0: Host took too long to start, waited 16000 microseconds.
> xhci_hcd 0000:03:00.0: startup error -19
> xhci_hcd 0000:03:00.0: USB bus 2 deregistered
> xhci_hcd 0000:03:00.0: remove, state 1
> usb usb1: USB disconnect, device number 1
> xhci_hcd 0000:03:00.0: USB bus 1 deregistered
> usbcore: registered new interface driver usb-storage
>
> As you can see `dma_direct_alloc' hands out addresses outside the 32-bit
> physical range and then the USB host controller cannot be communicated to.
> Also some memory has likely got corrupted (or random MMIO poked at).
>
> Then with this change applied the messages change to these:
>
> xhci_hcd 0000:03:00.0: assign IRQ: got 56
> xhci_hcd 0000:03:00.0: enabling bus mastering
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca050000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca054000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca058000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca05c000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca060000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca064000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca068000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca06c000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca070000
> xhci_hcd 0000:03:00.0: hcc params 0x014051c7 hci version 0x100 quirks 0x0000000100000090
> xhci_hcd 0000:03:00.0: enabling Mem-Wr-Inval
> usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.19
> usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> usb usb1: Product: xHCI Host Controller
> usb usb1: Manufacturer: Linux 4.19.0 xhci-hcd
> usb usb1: SerialNumber: 0000:03:00.0
> hub 1-0:1.0: USB hub found
> hub 1-0:1.0: 2 ports detected
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 2
> xhci_hcd 0000:03:00.0: Host supports USB 3.0 SuperSpeed
> usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
> usb usb2: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 4.19
> usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> usb usb2: Product: xHCI Host Controller
> usb usb2: Manufacturer: Linux 4.19.0 xhci-hcd
> usb usb2: SerialNumber: 0000:03:00.0
> hub 2-0:1.0: USB hub found
> hub 2-0:1.0: 2 ports detected
> usbcore: registered new interface driver usb-storage
>
> and then later on these:
>
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca074000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca078000
> usb 2-1: new SuperSpeed Gen 1 USB device number 2 using xhci_hcd
> usb 2-1: New USB device found, idVendor=0781, idProduct=5583, bcdDevice= 1.00
> usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> usb 2-1: Product: Ultra Fit
> usb 2-1: Manufacturer: SanDisk
> usb 2-1: SerialNumber: 4C531001340112110513
> usb-storage 2-1:1.0: USB Mass Storage device detected
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000000ca07c000
> scsi host5: usb-storage 2-1:1.0
> scsi 5:0:0:0: Direct-Access SanDisk Ultra Fit 1.00 PQ: 0 ANSI: 6
> sd 5:0:0:0: Attached scsi generic sg2 type 0
> sd 5:0:0:0: [sdc] 120127488 512-byte logical blocks: (61.5 GB/57.3 GiB)
> sd 5:0:0:0: [sdc] Write Protect is off
> sd 5:0:0:0: [sdc] Mode Sense: 43 00 00 00
> sd 5:0:0:0: [sdc] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
> sdc: sdc1 sdc2
> sd 5:0:0:0: [sdc] Attached SCSI removable disk
>
> moving addresses handed out by `dma_direct_alloc' to the 32-bit physical
> range and consequently both the USB host controller and the storage device
> behind responsive.
>
> If moved to one of the PCI slots down the HT link it works correctly with
> 64-bit addressing:
>
> xhci_hcd 0000:03:00.0: assign IRQ: got 58
> xhci_hcd 0000:03:00.0: enabling bus mastering
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185aec000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185af0000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185af8000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185afc000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b00000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b04000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b08000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b0c000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a800000185b10000
> xhci_hcd 0000:03:00.0: hcc params 0x014051c7 hci version 0x100 quirks 0x0000000100000090
> xhci_hcd 0000:03:00.0: enabling Mem-Wr-Inval
> usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 4.20
> usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> usb usb1: Product: xHCI Host Controller
> usb usb1: Manufacturer: Linux 4.20.0-rc1 xhci-hcd
> usb usb1: SerialNumber: 0000:03:00.0
> hub 1-0:1.0: USB hub found
> hub 1-0:1.0: 2 ports detected
> xhci_hcd 0000:03:00.0: xHCI Host Controller
> xhci_hcd 0000:03:00.0: new USB bus registered, assigned bus number 2
> xhci_hcd 0000:03:00.0: Host supports USB 3.0 SuperSpeed
> usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
> usb usb2: New USB device found, idVendor=1d6b, idProduct=0003, bcdDevice= 4.20
> usb usb2: New USB device strings: Mfr=3, Product=2, SerialNumber=1
> usb usb2: Product: xHCI Host Controller
> usb usb2: Manufacturer: Linux 4.20.0-rc1 xhci-hcd
> usb usb2: SerialNumber: 0000:03:00.0
> hub 2-0:1.0: USB hub found
> hub 2-0:1.0: 2 ports detected
> usbcore: registered new interface driver usb-storage
>
> and:
>
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000001830d4000
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000001830d8000
> usb 2-1: new SuperSpeed Gen 1 USB device number 2 using xhci_hcd
> usb 2-1: New USB device found, idVendor=0781, idProduct=5583, bcdDevice= 1.00
> usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> usb 2-1: Product: Ultra Fit
> usb 2-1: Manufacturer: SanDisk
> usb 2-1: SerialNumber: 4C531001340112110513
> usb-storage 2-1:1.0: USB Mass Storage device detected
> xhci_hcd 0000:03:00.0: dma_direct_alloc: coherent: 1
> xhci_hcd 0000:03:00.0: dma_direct_alloc: returned: a8000001830dc000
> scsi host5: usb-storage 2-1:1.0
> scsi 5:0:0:0: Direct-Access SanDisk Ultra Fit 1.00 PQ: 0 ANSI: 6
> sd 5:0:0:0: Attached scsi generic sg2 type 0
> sd 5:0:0:0: [sdc] 120127488 512-byte logical blocks: (61.5 GB/57.3 GiB)
> sd 5:0:0:0: [sdc] Write Protect is off
> sd 5:0:0:0: [sdc] Mode Sense: 43 00 00 00
> sd 5:0:0:0: [sdc] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
>
> confirming that indeed the devices down the PCI-HT bridge don't need the
> bus mask to be set.
>
> NB the reason for the bus address of the XHCI PCI device remaining the
> same (0000:03:00.0) in the logs above regardless of the slot it has been
> plugged in is that the option board actually includes a PCI-PCIe bridge
> the actual XHCI device is behind, and that secondary PCIe link happens to
> get the same bus number in enumeration.
>
> The BCM1480 SOC may or may not require a similar quirk, but I have no
> documentation nor hardware to check with, so let's leave it for someone
> who can verify it. My understanding is it implements a PCI-X rather than
> a plain PCI host bridge, so the limitation may well have been lifted in
> the redesign.
>
> Maciej
> ---
> arch/mips/pci/fixup-sb1250.c | 48 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 48 insertions(+)
>
> linux-mips-sibyte-sb1250-bus-dma-mask.diff
> Index: linux-20181104-swarm64-eb/arch/mips/pci/fixup-sb1250.c
> ===================================================================
> --- linux-20181104-swarm64-eb.orig/arch/mips/pci/fixup-sb1250.c
> +++ linux-20181104-swarm64-eb/arch/mips/pci/fixup-sb1250.c
> @@ -1,6 +1,7 @@
> /*
> * Copyright (C) 2004, 2006 MIPS Technologies, Inc. All rights reserved.
> * Author: Maciej W. Rozycki <macro@xxxxxxxx>
> + * Copyright (C) 2018 Maciej W. Rozycki
> *
> * This program is free software; you can redistribute it and/or
> * modify it under the terms of the GNU General Public License
> @@ -8,6 +9,7 @@
> * 2 of the License, or (at your option) any later version.
> */
>
> +#include <linux/dma-mapping.h>
> #include <linux/pci.h>
>
> /*
> @@ -22,6 +24,52 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SI
> quirk_sb1250_pci);
>
> /*
> + * The BCM1250, etc. PCI host bridge does not support DAC on its 32-bit
> + * bus, so we set the bus's DMA mask accordingly. However the HT link
> + * down the artificial PCI-HT bridge supports 40-bit addressing and the
> + * SP1011 HT-PCI bridge downstream supports both DAC and a 64-bit bus
> + * width, so we record the PCI-HT bridge's secondary and subordinate bus
> + * numbers and do not set the mask for devices present in the inclusive
> + * range of those.
> + */
> +struct sb1250_bus_dma_mask_exclude {
> + bool set;
> + unsigned char start;
> + unsigned char end;
> +};
> +
> +static int sb1250_bus_dma_mask(struct pci_dev *dev, void *data)
> +{
> + struct sb1250_bus_dma_mask_exclude *exclude = data;
> +
> + if (!exclude->set && (dev->vendor == PCI_VENDOR_ID_SIBYTE &&
> + dev->device == PCI_DEVICE_ID_BCM1250_HT)) {
> + exclude->start = dev->subordinate->number;
> + exclude->end = pci_bus_max_busnr(dev->subordinate);
> + exclude->set = true;
> + dev_dbg(&dev->dev, "not disabling DAC for [bus %02x-%02x]",
> + exclude->start, exclude->end);
> + } else if (!exclude->set ||
> + (exclude->set && (dev->bus->number < exclude->start ||
> + dev->bus->number > exclude->end))) {
> + dev_dbg(&dev->dev, "disabling DAC for device");
> + dev->dev.bus_dma_mask = DMA_BIT_MASK(32);
> + } else {
> + dev_dbg(&dev->dev, "not disabling DAC for device");
> + }
> + return 0;

Hmm, these conditions look very hard to read to me. Wouldn't this
have the same effect?

if (exclude->set)
return;

if (dev->vendor == PCI_VENDOR_ID_SIBYTE &&
dev->device == PCI_DEVICE_ID_BCM1250_HT) {
exclude->start = dev->subordinate->number;
exclude->end = pci_bus_max_busnr(dev->subordinate);
exclude->set = true;
dev_dbg(&dev->dev, "not disabling DAC for [bus %02x-%02x]",
exclude->start, exclude->end);
return;
}

if (dev->bus->number < exclude->start ||
dev->bus->number > exclude->end))) {
dev_dbg(&dev->dev, "disabling DAC for device");
dev->dev.bus_dma_mask = DMA_BIT_MASK(32);
return;
}

dev_dbg(&dev->dev, "not disabling DAC for device");
return 0;

Otherwise this looks fine to me:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>

Next message: Christoph Hellwig: "Re: [PATCH 2/2] MIPS: SiByte: Enable swiotlb for SWARM and BigSur"
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In reply to: Maciej W. Rozycki: "[PATCH 1/2] MIPS: SiByte: Set 32-bit bus mask for BCM1250 PCI"
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