On Mon, 27 Oct 2008 17:22:06 +0100
Matthias Kaehlcke <mkaehlcke@xxxxxxx> wrote:
> hi,
>
> James Bottomley wrote:
> > On Mon, 2008-10-27 at 12:35 +0100, Matthias Kaehlcke wrote:
> >>
> >> James Bottomley wrote:
> >>> On Fri, 2008-10-24 at 09:05 +0200, Matthias Kaehlcke wrote:
> >>>>
> >>>> inserting a Verbatim 4GB USB stick in a ep9307 based device running
> >>>> kernel 2.6.27 results in the following Oops:
> >>>>
> >>>> [42949395.050000] usb 1-3: new full speed USB device using ep93xx-ohci
> >>>> and address 2
> >>>> [42949395.250000] usb 1-3: configuration #1 chosen from 1 choice
> >>>> [42949395.260000] scsi0 : SCSI emulation for USB Mass Storage devices
> >>>> [42949395.270000] usb 1-3: New USB device found, idVendor=13fe,
> >>>> idProduct=1f23
> >>>> [42949395.280000] usb 1-3: New USB device strings: Mfr=1, Product=2,
> >>>> SerialNumber=3
> >>>> [42949395.280000] usb 1-3: Product: STORE N GO
> >>>> [42949395.300000] usb 1-3: Manufacturer: Verbatim
> >>>> [42949395.310000] usb 1-3: SerialNumber: 078813D90478
> >>>> [42949400.280000] Unable to handle kernel NULL pointer dereference at
> >>>> virtual address 00000003
> >>>> [42949400.280000] pgd = c0648000
> >>>> [42949400.300000] [00000003] *pgd=c0647031, *pte=00000000, *ppte=00000000
> >>>> [42949400.300000] Internal error: Oops: 13 [#1] PREEMPT
> >>>> [42949400.300000] Modules linked in:
> >>>> [42949400.300000] CPU: 0 Not tainted (2.6.27 #3)
> >>>> [42949400.300000] PC is at scsi_calculate_bounce_limit+0x3c/0x44
> >>> Best guess is this line:
> >>>
> >>> if (host_dev && host_dev->dma_mask)
> >>> bounce_limit = *host_dev->dma_mask;
> >>>
> >>> I'd guess host_dev->dma_mask contains 0x3 ... could this be some sort of
> >>> ARM setup problem?
> >> thanks for having a look!
> >>
> >> i could figure out the difference between 2.6.26.3 and 2.6.27 that
> >> triggers the Oops:
> >>
> >> diff -u linux-2.6.26.3/include/asm-arm/pci.h
> >> linux-2.6.27/arch/arm/include/asm/pci.h
> >>
> >> ...
> >> @@ -30,7 +30,7 @@
> >> * The networking and block device layers use this boolean for bounce
> >> * buffer decisions.
> >> */
> >> -#define PCI_DMA_BUS_IS_PHYS (0)
> >> +#define PCI_DMA_BUS_IS_PHYS (1)
> >>
> >> /*
> >> * Whether pci_unmap_{single,page} is a nop depends upon the
> >> ...
> >>
> >> this change affects the following piece of code in
> >> scsi_calculate_bounce_limit():
> >>
> >> if (!PCI_DMA_BUS_IS_PHYS)
> >> return BLK_BOUNCE_ANY;
> >>
> >> host_dev = scsi_get_device(shost);
> >> if (host_dev && host_dev->dma_mask)
> >> bounce_limit = *host_dev->dma_mask;
> >>
> >>
> >> host_dev->dma_mask is 0xffffffff and we try to dereference the pointer
> >
> > So the host_dev is some type of arm platform device? If so, it's got
> > it's dma_mask set up wrongly. it's a pointer in struct device and is
> > supposed to point to the real u64 quantity located within the actual
> > enclosing device.
>
> thanks a lot for the pointer, i think i fixed the problem:
>
> --- linux-2.6.27.org/arch/arm/mach-ep93xx/core.c 2008-10-10
> 00:13:53.000000000 +0200
> +++ linux-2.6.27/arch/arm/mach-ep93xx/core.c 2008-10-27
> 17:00:42.000000000 +0100
> @@ -26,6 +26,7 @@
> #include <linux/serial_core.h>
> #include <linux/device.h>
> #include <linux/mm.h>
> +#include <linux/dma-mapping.h>
> #include <linux/time.h>
> #include <linux/timex.h>
> #include <linux/delay.h>
> @@ -450,12 +451,14 @@
> },
> };
>
> +static u64 ep93xx_ohci_dmamask = DMA_BIT_MASK(32);
> +
> static struct platform_device ep93xx_ohci_device = {
> .name = "ep93xx-ohci",
> .id = -1,
> .dev = {
> - .dma_mask = (void *)0xffffffff,
> - .coherent_dma_mask = 0xffffffff,
> + .dma_mask = &ep93xx_ohci_dmamask,
> + .coherent_dma_mask = DMA_BIT_MASK(32),
> },
> .num_resources = ARRAY_SIZE(ep93xx_ohci_resources),
> .resource = ep93xx_ohci_resources,
You can do this in a simpler way (it's the popular way to do this):
@@ -453,8 +454,8 @@ static struct platform_device ep93xx_ohci_device = {
.name = "ep93xx-ohci",
.id = -1,
.dev = {
- .dma_mask = (void *)0xffffffff,
- .coherent_dma_mask = 0xffffffff,
+ .dma_mask = &ep93xx_ohci_device.dev.coherent_dma_mask,
+ .coherent_dma_mask = DMA_BIT_MASK(32),
},
.num_resources = ARRAY_SIZE(ep93xx_ohci_resources),
.resource = ep93xx_ohci_resources,
--
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