: ixp4xx: Fix 3.7 regression for IXP4xx ethernet driver

arch/arm/mach-ixp4xx/common-pci.c int ixp4xx_setup(int nr, struct pci_sys_data *sys) · line 486

When you move this function, you should really move the 'EXPORT_SYMBOL' along with it.

Arnd

Review int ixp4xx_setup(int nr, struct pci_sys_data *sys) · line 489

Originally, coherent masks equal to 64 MiB or wider are accepted.

arch/arm/mach-ixp4xx/common.c

Now, you reject them. However, with coherent allocations, big masks (usually 32-bit) are ok. They have to be internally limited to 64 MiB, though.
It's a narrow mask (e.g. 16 MiB) which can't be used, because we only have two memory pools (4 GiB and 64 MiB), and we simply have no means to request e.g. memory from 16 MiB range. Doesn't matter in practice, otherwise we would have additional memory pool.

This differs a bit from the streaming mask. For streaming, we still accept basically everything (because we obviously want to support 32-bit capable devices) and we limit the masks to 64 MiB internally, but we then have to use dmabounce or whatever (perhaps swiotlb could be an option?).
Also, we can limit some heavy duty allocations to 64 MiB (e.g. skbuffs on routers, with a custom patch). We don't do DAC, IXP4xx address space is 32-bit anyway. BTW possibility to use some system-wide DMA mask while creating skbuffs, disk buffers etc. could be an improvement (drivers would still need to check the addresses with dmabounce).

Believe it or not, the correct patch is the one I'm attaching. One can add extra *set_masks* (e.g. the new call setting both streaming and coherent masks) in the drivers, but essentially it must do what this one does. Also, converting the mask (in the dev struct) from a pointer to a simple value would IMHO make sense, too.

Also, comparing bit masks with ">=" etc. doesn't look very valid to me. What if some device wants a mask which isn't a power of 2 - 1?

I'm unable to look at this ATM but I will update the patch to the new kernel, perhaps soon.

IXP4xx: Fix DMA masks.

Now, devices will have 32-bit default DMA masks (0xFFFFFFFF) as per DMA API, and the masks will actually work.

index 6d6bde3..cefb80b 100644
@@ -316,32 +316,6 @@ static int abort_handler(unsigned long addr, unsigned int fsr, struct pt_regs *r
 }
 
 
-static int ixp4xx_needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
-{
-	return (dma_addr + size) >= SZ_64M;
-}
-
-/*
- * Setup DMA mask to 64MB on PCI devices. Ignore all other devices.
- */
-static int ixp4xx_pci_platform_notify(struct device *dev)
-{
-	if(dev->bus == &pci_bus_type) {
-		*dev->dma_mask =  SZ_64M - 1;
-		dev->coherent_dma_mask = SZ_64M - 1;
-		dmabounce_register_dev(dev, 2048, 4096, ixp4xx_needs_bounce);
-	}
-	return 0;
-}
-
-static int ixp4xx_pci_platform_notify_remove(struct device *dev)
-{
-	if(dev->bus == &pci_bus_type) {
-		dmabounce_unregister_dev(dev);
-	}
-	return 0;
-}
-
 void __init ixp4xx_pci_preinit(void)
 {
 	unsigned long cpuid = read_cpuid_id();

@@ -475,20 +449,8 @@ int ixp4xx_setup(int nr, struct pci_sys_data *sys)
 	pci_add_resource_offset(&sys->resources, &res[0], sys->io_offset);
 	pci_add_resource_offset(&sys->resources, &res[1], sys->mem_offset);
 
-	platform_notify = ixp4xx_pci_platform_notify;
-	platform_notify_remove = ixp4xx_pci_platform_notify_remove;
-
 	return 1;
 }
 
-int dma_set_coherent_mask(struct device *dev, u64 mask)
-{
-	if (mask >= SZ_64M - 1)
-		return 0;
-
-	return -EIO;
-}
-
 EXPORT_SYMBOL(ixp4xx_pci_read);
 EXPORT_SYMBOL(ixp4xx_pci_write);
-EXPORT_SYMBOL(dma_set_coherent_mask);

Krzysztof Halasa

Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland

arch/arm/mach-ixp4xx/common.c void ixp4xx_restart(enum reboot_mode mode, const char *cmd) · line 580

To me it seems the conditional compilation is superfluous - dev_is_pci is used to check for PCI-devices anyway, and the compiler should be smart enough to remove dead code for the non-PCI case.

arch/arm/mach-ixp4xx/common.c void ixp4xx_restart(enum reboot_mode mode, const char *cmd) · line 588

if (dev_is_pci(dev))

arch/arm/mach-ixp4xx/common.c void ixp4xx_restart(enum reboot_mode mode, const char *cmd) · line 592

// Simon