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SubjectRe: bcm2711_thermal: Kernel panic - not syncing: Asynchronous SError Interrupt
On Wed, 10 Feb 2021 14:15:46 +0100
Nicolas Saenz Julienne <nsaenzjulienne@suse.de> wrote:

> [ Add Robin, Catalin and Florian in case they want to chime in ]
>
> Hi Juerg, thanks for the report!
>
> On Wed, 2021-02-10 at 11:48 +0100, Juerg Haefliger wrote:
> > Trying to dump the BCM2711 registers kills the kernel:
> >
> > # cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2000/range
> > 0-efc
> > # cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2000/registers
> >
> > [ 62.857661] SError Interrupt on CPU1, code 0xbf000002 -- SError
>
> So ESR's IDS (bit 24) is set, which means it's an 'Implementation Defined
> SError,' hence IIUC the rest of the error code is meaningless to anyone outside
> of Broadcom/RPi.
>
> The regmap is created through the following syscon device:
>
> avs_monitor: avs-monitor@7d5d2000 {
> compatible = "brcm,bcm2711-avs-monitor",
> "syscon", "simple-mfd";
> reg = <0x7d5d2000 0xf00>;
>
> thermal: thermal {
> compatible = "brcm,bcm2711-thermal";
> #thermal-sensor-cells = <0>;
> };
> };
>
> I've done some tests with devmem, and the whole <0x7d5d2000 0xf00> range is
> full of addresses that trigger this same error. Also note that as per Florian's
> comments[1]: "AVS_RO_REGISTERS_0: 0x7d5d2200 - 0x7d5d22e3." But from what I can
> tell, at least 0x7d5d22b0 seems to be faulty too.
>
> Any ideas/comments? My guess is that those addresses are marked somehow as
> secure, and only for VC4 to access (VC4 is RPi4's co-processor). Ultimately,
> the solution is to narrow the register range exposed by avs-monitor to whatever
> bcm2711-thermal needs (which is ATM a single 32bit register).

Yeah, that's what I tried but wasn't sure if that's the correct approach or
if there was something wrong with the DTB (which I know virtually nothing
about).

With [1] I get seemingly the correct behavior:

# cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2200/range
0-0
# cat /sys/kernel/debug/regmap/dummy-avs-monitor\@fd5d2200/registers
0: 000106fa
# cat /sys/class/thermal/thermal_zone0/temp
39433

On a different note, how did you come up with that address range in the DTB?
Is that public information?

...Juerg


[1]
diff --git a/arch/arm/boot/dts/bcm2711.dtsi b/arch/arm/boot/dts/bcm2711.dtsi
index 4847dd305317..a7059967aab1 100644
--- a/arch/arm/boot/dts/bcm2711.dtsi
+++ b/arch/arm/boot/dts/bcm2711.dtsi
@@ -65,10 +65,10 @@ gicv2: interrupt-controller@40041000 {
IRQ_TYPE_LEVEL_HIGH)>;
};

- avs_monitor: avs-monitor@7d5d2000 {
+ avs_monitor: avs-monitor@7d5d2200 {
compatible = "brcm,bcm2711-avs-monitor",
"syscon", "simple-mfd";
- reg = <0x7d5d2000 0xf00>;
+ reg = <0x7d5d2200 0x4>;

thermal: thermal {
compatible = "brcm,bcm2711-thermal";
diff --git a/drivers/thermal/broadcom/bcm2711_thermal.c b/drivers/thermal/broadcom/bcm2711_thermal.c
index 67c2a737bc9d..3b5a84402b89 100644
--- a/drivers/thermal/broadcom/bcm2711_thermal.c
+++ b/drivers/thermal/broadcom/bcm2711_thermal.c
@@ -22,7 +22,7 @@

#include "../thermal_hwmon.h"

-#define AVS_RO_TEMP_STATUS 0x200
+#define AVS_RO_TEMP_STATUS 0x0 /* address 0x7d5d2200 */
#define AVS_RO_TEMP_STATUS_VALID_MSK (BIT(16) | BIT(10))
#define AVS_RO_TEMP_STATUS_DATA_MSK GENMASK(9, 0)



> Regards,
> Nicolas
>
> [1] https://lore.kernel.org/linux-pm/82125042-684a-b4e2-fbaa-45a393b2ce5e@gmx.net/
>
> > [ 62.857671] CPU: 1 PID: 478 Comm: cat Not tainted 5.11.0-rc7 #4
> > [ 62.857674] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)
> > [ 62.857676] pstate: 20000085 (nzCv daIf -PAN -UAO -TCO BTYPE=--)
> > [ 62.857679] pc : regmap_mmio_read32le+0x1c/0x34
> > [ 62.857681] lr : regmap_mmio_read+0x50/0x80
> > [ 62.857682] sp : ffff8000105c3c00
> > [ 62.857685] x29: ffff8000105c3c00 x28: 0000000000000014
> > [ 62.857694] x27: 0000000000000014 x26: ffffd2ea1c2060b0
> > [ 62.857699] x25: ffff4e34408ecc00 x24: 0000000000000efc
> > [ 62.857704] x23: ffff8000105c3e20 x22: ffff8000105c3d3c
> > [ 62.857710] x21: ffff8000105c3d3c x20: 0000000000000014
> > [ 62.857715] x19: ffff4e344037a900 x18: 0000000000000020
> > [ 62.857720] x17: 0000000000000000 x16: 0000000000000000
> > [ 62.857725] x15: ffff4e3447ac40f0 x14: 0000000000000003
> > [ 62.857730] x13: ffff4e34422c0000 x12: ffff4e34422a0046
> > [ 62.857735] x11: ffffd2ea1c8765e0 x10: 0000000000000000
> > [ 62.857741] x9 : ffffd2ea1b9495a0 x8 : ffff4e34429ef980
> > [ 62.857746] x7 : 000000000000000f x6 : ffff4e34422a004b
> > [ 62.857751] x5 : 00000000fffffff9 x4 : 0000000000000000
> > [ 62.857757] x3 : ffffd2ea1b949550 x2 : ffffd2ea1b949330
> > [ 62.857761] x1 : 0000000000000014 x0 : 0000000000000000
> > [ 62.857767] Kernel panic - not syncing: Asynchronous SError Interrupt
> > [ 62.857770] CPU: 1 PID: 478 Comm: cat Not tainted 5.11.0-rc7 #4
> > [ 62.857773] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)
> > [ 62.857775] Call trace:
> > [ 62.857777] dump_backtrace+0x0/0x1e0
> > [ 62.857778] show_stack+0x24/0x70
> > [ 62.857780] dump_stack+0xd0/0x12c
> > [ 62.857782] panic+0x168/0x370
> > [ 62.857783] nmi_panic+0x98/0xa0
> > [ 62.857786] arm64_serror_panic+0x8c/0x98
> > [ 62.857787] do_serror+0x3c/0x6c
> > [ 62.857789] el1_error+0x78/0xf0
> > [ 62.857791] regmap_mmio_read32le+0x1c/0x34
> > [ 62.857793] _regmap_bus_reg_read+0x24/0x30
> > [ 62.857795] _regmap_read+0x6c/0x17c
> > [ 62.857797] regmap_read+0x58/0x84
> > [ 62.857799] regmap_read_debugfs+0x138/0x3f4
> > [ 62.857801] regmap_map_read_file+0x34/0x40
> > [ 62.857803] full_proxy_read+0x6c/0xc0
> > [ 62.857805] vfs_read+0xb8/0x1e4
> > [ 62.857807] ksys_read+0x78/0x10c
> > [ 62.857809] __arm64_sys_read+0x28/0x34
> > [ 62.857811] el0_svc_common.constprop.0+0x7c/0x194
> > [ 62.857813] do_el0_svc+0x30/0x9c
> > [ 62.857814] el0_svc+0x20/0x30
> > [ 62.857816] el0_sync_handler+0x1a4/0x1b0
> > [ 62.857818] el0_sync+0x174/0x180
> > [ 62.857842] SMP: stopping secondary CPUs
> > [ 62.857845] Kernel Offset: 0x52ea0b080000 from 0xffff800010000000
> > [ 62.857847] PHYS_OFFSET: 0xffffb1cc00000000
> > [ 62.857849] CPU features: 0x00240022,61806000
> > [ 62.857851] Memory Limit: none
> >
> > Sprinkling printks around regmap_read [1] shows that reading from 0x14 (20)
> > seems to cause the issue:
> >
> >
> > [ 40.456230] map=ffff020a069c9c00, from=0, to=3836, count=131072
> > [ 40.462520] map=ffff020a069c9c00, i=0
> > [ 40.466319] ret=0, val=0
> > [ 40.468922] map=ffff020a069c9c00, i=4
> > [ 40.472684] ret=0, val=0
> > [ 40.475292] map=ffff020a069c9c00, i=8
> > [ 40.479048] ret=0, val=0
> > [ 40.481649] map=ffff020a069c9c00, i=12
> > [ 40.485492] ret=0, val=0
> > [ 40.488080] map=ffff020a069c9c00, i=16
> > [ 40.491922] ret=0, val=0
> > [ 40.494523] map=ffff020a069c9c00, i=20
> > [ 40.498497] SError Interrupt on CPU0, code 0xbf000002 -- SError
> > [ 40.498499] CPU: 0 PID: 486 Comm: cat Not tainted 5.11.0-rc7+ #8
> > [ 40.498501] Hardware name: Raspberry Pi 4 Model B Rev 1.2 (DT)
> >
> >
> > ...Juerg
> >
> > [1]
> > diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
> > index ff2ee87987c7..9465f5a2f3b8 100644
> > --- a/drivers/base/regmap/regmap-debugfs.c
> > +++ b/drivers/base/regmap/regmap-debugfs.c
> > @@ -229,6 +229,7 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
> >         if (count > (PAGE_SIZE << (MAX_ORDER - 1)))
> >                 count = PAGE_SIZE << (MAX_ORDER - 1);
> >  
> >
> > + printk("map=%px, from=%d, to=%d, count=%ld\n", map, from, to, count);
> >         buf = kmalloc(count, GFP_KERNEL);
> >         if (!buf)
> >                 return -ENOMEM;
> > @@ -253,7 +254,9 @@ static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
> >                         buf_pos += map->debugfs_reg_len + 2;
> >  
> >
> >                         /* Format the value, write all X if we can't read */
> > + printk("map=%px, i=%d\n", map, i);
> >                         ret = regmap_read(map, i, &val);
> > + printk("ret=%ld, val=%x\n", ret, val);
> >                         if (ret == 0)
> >                                 snprintf(buf + buf_pos, count - buf_pos,
> >                                          "%.*x", map->debugfs_val_len, val);
> >
>
>
>

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