Re: [PATCH] mips: bmips: BCM6358: disable arch_sync_dma_for_cpu_all()

[Florian Fainelli <f.fainelli@gmail.com>]

On 3/10/2023 4:13 AM, Álvaro Fernández Rojas wrote:
> 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..

Did you pinpoint which specific instruction within 
arch_sync_dma_for_cpu_all() is causing the reserved instruction exception?

> 
> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
> ---
>   arch/mips/bmips/dma.c   | 5 +++++
>   arch/mips/bmips/setup.c | 5 +++++
>   2 files changed, 10 insertions(+)
> 
> diff --git a/arch/mips/bmips/dma.c b/arch/mips/bmips/dma.c
> index 33788668cbdb..3769d5efdede 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_enabled = 1;

bool bmips_dma_sync_disabled;

> +
>   void arch_sync_dma_for_cpu_all(void)
>   {
>   	void __iomem *cbr = BMIPS_GET_CBR();
>   	u32 cfg;
>   
> +	if (!bmips_dma_sync_enabled)
> +		return;

if (bmips_dma_sync_disabled)

> +
>   	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..825e85e14010 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_enabled;
> +
>   static const unsigned long kbase = VMLINUX_LOAD_ADDRESS & 0xfff00000;
>   
>   struct bmips_quirk {
> @@ -104,6 +106,9 @@ 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 */
> +	bmips_dma_sync_enabled = 0;

bmips_dma_sync_disabled = true;

>   }
>   
>   static void bcm6368_quirks(void)

-- 
Florian