[PATCH v2] mips: bmips: BCM6358: disable arch_sync_dma_for_cpu_all() for TP1

["Álvaro Fernández Rojas" <noltari@gmail.com>]

arch_sync_dma_for_cpu_all() causes kernel panics on BCM6358 with EHCI/OHCI:
[    3.881739] usb 1-1: new high-speed USB device number 2 using ehci-platform
[    3.895011] Reserved instruction in kernel code[#1]:
[    3.900113] CPU: 0 PID: 1 Comm: init Not tainted 5.10.16 #0
[    3.905829] $ 0   : 00000000 10008700 00000000 77d94060
[    3.911238] $ 4   : 7fd1f088 00000000 81431cac 81431ca0
[    3.916641] $ 8   : 00000000 ffffefff 8075cd34 00000000
[    3.922043] $12   : 806f8d40 f3e812b7 00000000 000d9aaa
[    3.927446] $16   : 7fd1f068 7fd1f080 7ff559b8 81428470
[    3.932848] $20   : 00000000 00000000 55590000 77d70000
[    3.938251] $24   : 00000018 00000010
[    3.943655] $28   : 81430000 81431e60 81431f28 800157fc
[    3.949058] Hi    : 00000000
[    3.952013] Lo    : 00000000
[    3.955019] epc   : 80015808 setup_sigcontext+0x54/0x24c
[    3.960464] ra    : 800157fc setup_sigcontext+0x48/0x24c
[    3.965913] Status: 10008703	KERNEL EXL IE
[    3.970216] Cause : 00800028 (ExcCode 0a)
[    3.974340] PrId  : 0002a010 (Broadcom BMIPS4350)
[    3.979170] Modules linked in: ohci_platform ohci_hcd fsl_mph_dr_of ehci_platform ehci_fsl ehci_hcd gpio_button_hotplug usbcore nls_base usb_common
[    3.992907] Process init (pid: 1, threadinfo=(ptrval), task=(ptrval), tls=77e22ec8)
[    4.000776] Stack : 81431ef4 7fd1f080 81431f28 81428470 7fd1f068 81431edc 7ff559b8 81428470
[    4.009467]         81431f28 7fd1f080 55590000 77d70000 77d5498c 80015c70 806f0000 8063ae74
[    4.018149]         08100002 81431f28 0000000a 08100002 81431f28 0000000a 77d6b418 00000003
[    4.026831]         ffffffff 80016414 80080734 81431ecc 81431ecc 00000001 00000000 04000000
[    4.035512]         77d54874 00000000 00000000 00000000 00000000 00000012 00000002 00000000
[    4.044196]         ...
[    4.046706] Call Trace:
[    4.049238] [<80015808>] setup_sigcontext+0x54/0x24c
[    4.054356] [<80015c70>] setup_frame+0xdc/0x124
[    4.059015] [<80016414>] do_notify_resume+0x1dc/0x288
[    4.064207] [<80011b50>] work_notifysig+0x10/0x18
[    4.069036]
[    4.070538] Code: 8fc300b4  00001025  26240008 <ac820000> ac830004  3c048063  0c0228aa  24846a00  26240010
[    4.080686]
[    4.082517] ---[ end trace 22a8edb41f5f983b ]---
[    4.087374] Kernel panic - not syncing: Fatal exception
[    4.092753] Rebooting in 1 seconds..

This only happens when booting from TP1 instead of TP0.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
 v2: check if we're running on TP1 and invert logic.

 arch/mips/bmips/dma.c   | 5 +++++
 arch/mips/bmips/setup.c | 9 +++++++++
 2 files changed, 14 insertions(+)

diff --git a/arch/mips/bmips/dma.c b/arch/mips/bmips/dma.c
index 33788668cbdb..2e470ef8d30f 100644
--- a/arch/mips/bmips/dma.c
+++ b/arch/mips/bmips/dma.c
@@ -5,11 +5,16 @@
 #include <asm/bmips.h>
 #include <asm/io.h>
 
+int bmips_dma_sync_disable = 0;
+
 void arch_sync_dma_for_cpu_all(void)
 {
 	void __iomem *cbr = BMIPS_GET_CBR();
 	u32 cfg;
 
+	if (bmips_dma_sync_disable)
+		return;
+
 	if (boot_cpu_type() != CPU_BMIPS3300 &&
 	    boot_cpu_type() != CPU_BMIPS4350 &&
 	    boot_cpu_type() != CPU_BMIPS4380)
diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index e95b3f78e7cd..15543e8d5b0c 100644
--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -35,6 +35,8 @@
 #define REG_BCM6328_OTP		((void __iomem *)CKSEG1ADDR(0x1000062c))
 #define BCM6328_TP1_DISABLED	BIT(9)
 
+extern int bmips_dma_sync_disable;
+
 static const unsigned long kbase = VMLINUX_LOAD_ADDRESS & 0xfff00000;
 
 struct bmips_quirk {
@@ -104,6 +106,13 @@ static void bcm6358_quirks(void)
 	 * disable SMP for now
 	 */
 	bmips_smp_enabled = 0;
+
+	/*
+	 * ARCH_HAS_SYNC_DMA_FOR_CPU_ALL causes kernel panics on BCM6358 when
+	 * booting from TP1
+	 */
+	if (read_c0_brcm_cmt_local() & (1 << 31))
+		bmips_dma_sync_disable = 1;
 }
 
 static void bcm6368_quirks(void)
-- 
2.30.2