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From:   Guenter Roeck <linux@roeck-us.net>
To:     Joshua Thompson <funaho@jurai.org>
Cc:     Greg Ungerer <gerg@linux-m68k.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org,
        Guenter Roeck <linux@roeck-us.net>
Subject: [RFC PATCH] m68k: set dma and coherent masks for Macintosh SONIC based ethernet
Date:   Sat, 26 May 2018 16:53:05 -0700
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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 <linux@roeck-us.net>
---
Modeled after f61e64310b75 ("m68k: set dma and coherent masks for platform
FEC ethernets"). 

RFC: Is "nothing special about the DMA memory coherency" correect ?

 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