Re: [PATCH v2] r8169: set coherent DMA mask as well as streaming DMA mask

Ard Biesheuvel [off-list ref] :

PCI devices that are 64-bit DMA capable should set the coherent
DMA mask as well as the streaming DMA mask. On some architectures,
these are managed separately, and so the coherent DMA mask will be
left at its default value of 32 if it is not set explicitly. This
results in errors such as

     r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
     hwdev DMA mask = 0x00000000ffffffff, dev_addr = 0x00000080fbfff000
     swiotlb: coherent allocation failed for device 0000:02:00.0 size=4096
     CPU: 0 PID: 1062 Comm: systemd-udevd Not tainted 4.8.0+ #35
     Hardware name: AMD Seattle/Seattle, BIOS 10:53:24 Oct 13 2016

on systems without memory that is 32-bit addressable by PCI devices.

Signed-off-by: Ard Biesheuvel <redacted>

Acked-by: Francois Romieu <romieu@fr.zoreil.com>

Unless someone plans to plug an acenic, a 83820 (pci-e gem board, anyone ?)
on top of a pci <-> pci-e adapter on this kind of motherboard, no other
network driver that uses the pci_... dma api exhibits this mixed 32 / 64 bit
support bug. I haven't checked devices with 32 < mask < 64 nor plain DMA api
converted ones.

-- 
Ueimor