On Sat, 26 May 2018, Guenter Roeck wrote:
> As of commit 205e1b7f51e4 ("dma-mapping: warn when there is no
> coherent_dma_mask") the NatSemi SONIC Ethernet driver is issuing the
> following warning on driver initialization on Macintosh q800 systems.
>
> SONIC ethernet @50f0a000, MAC 08:00:07:12:34:56, IRQ 3
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516
> macsonic_init+0x6a/0x15a
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 4.17.0-rc6-mac-00286-g527f47c #1
> Stack from 0781fdd8:
> 0781fdd8 003615b3 000181ba 000005c4 07a24cbc 00000000 00000000
> 000020e8
> 07a24800 002c196c 0001824e 00334c06 00000204 001f782a 00000009 00000000
> 00000000 003358d9 001f782a 00334c06 00000204 00000003 00000000 07a24800
> 002b5cb6 000372ec 001f8b1a 07a24800 00359203 50f0a000 07a14a48 00000003
> 00000000 07845c0a 0039dcca 003c835c 003c835c 0035b924 001c19de 07845c00
> 07845c0a 0039dcca 001c06dc 07845c0a 0781fed8 00000007 0054d040 07845c0a
> Call Trace: [<000181ba>] __warn+0xc0/0xc2
> [<000020e8>] do_one_initcall+0x0/0x140
> [<0001824e>] warn_slowpath_null+0x26/0x2c
> [<001f782a>] macsonic_init+0x6a/0x15a
> [<001f782a>] macsonic_init+0x6a/0x15a
> [<002b5cb6>] memcmp+0x0/0x2a
> [<000372ec>] printk+0x0/0x18
> [<001f8b1a>] mac_sonic_platform_probe+0x380/0x404
>
> As per the warning the coherent_dma_mask is not set on this device.
> There is nothing special about the DMA memory coherency on this hardware
> so we can just set the mask to 32bits in the platform data for the FEC
> ethernet devices.
>
> Signed-off-by: Guenter Roeck <li...@roeck-us.net>
Acked-by: Finn Thain <fth...@telegraphics.com.au>
Geert, assuming that Guenter's patch is acceptable, would you also accept
a similar patch for the "macmace" platform device?
> ---
> Modeled after f61e64310b75 ("m68k: set dma and coherent masks for platform
> FEC ethernets").
>
> RFC: Is "nothing special about the DMA memory coherency" correect ?
>
As I understand it, "cache-coherence" is meaningless unless you have
multiple CPU cores and caches. If there's only one CPU core, its cache
can't be said to be "coherent" or "non-coherent". Moreover, DMA (direct
memory access) concerns an IO device and a memory, not a cache, so the
term "coherent dma" is bogus IMHO.
--
> arch/m68k/mac/config.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/arch/m68k/mac/config.c b/arch/m68k/mac/config.c
> index 0c3275aa0197..8e0476daddb8 100644
> --- a/arch/m68k/mac/config.c
> +++ b/arch/m68k/mac/config.c
> @@ -17,6 +17,7 @@
> #include <linux/tty.h>
> #include <linux/console.h>
> #include <linux/interrupt.h>
> +#include <linux/dma-mapping.h>
> /* keyb */
> #include <linux/random.h>
> #include <linux/delay.h>
> @@ -971,6 +972,15 @@ static const struct resource mac_scsi_ccl_rsrc[]
> __initconst = {
> },
> };
>
> +static struct platform_device macsonic_dev = {
> + .name = "macsonic",
> + .id = -1,
> + .dev = {
> + .dma_mask = &macsonic_dev.dev.coherent_dma_mask,
> + .coherent_dma_mask = DMA_BIT_MASK(32),
> + },
> +};
> +
> int __init mac_platform_init(void)
> {
> u8 *swim_base;
> @@ -1088,7 +1098,7 @@ int __init mac_platform_init(void)
>
> if (macintosh_config->ether_type == MAC_ETHER_SONIC ||
> macintosh_config->expansion_type == MAC_EXP_PDS_COMM)
> - platform_device_register_simple("macsonic", -1, NULL, 0);
> + platform_device_register(&macsonic_dev);
>
> if (macintosh_config->expansion_type == MAC_EXP_PDS ||
> macintosh_config->expansion_type == MAC_EXP_PDS_COMM)
> --
> 2.7.4
>
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