Hi. We have discovered an SPI regression when upgrading from 6.1.99 to a newer LTS version. Same error on kernel 6.6.71 and 6.12.8.
I think we have identified the problem down to the reference clock calculation that seems to end up to zero in the spi-omap2-mcspi driver.
Also we think it relates to commit 4c6ac5446d060f0bf435ccc8bc3aa7b7b5f718ad, where OMAP2_MCSPI_MAX_FREQ is used as fallback on error. In our case it seems to hit the else case.
Snippets for device tree, spi-omap2-mcspi driver and kernel divide by zero error log with dynamic debug enabled.
/Lars Pedersen
diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c index 67441b2cd603..8fedfc7db1fa 100644 --- a/drivers/spi/spi-omap2-mcspi.c +++ b/drivers/spi/spi-omap2-mcspi.c @@ -1559,12 +1559,13 @@ static int omap2_mcspi_probe(struct platform_device *pdev) dev_err(&pdev->dev, "Cannot request IRQ"); goto free_ctlr; } - + dev_dbg(&pdev->dev, "DEBUG_EXTRA pre calc\n"); mcspi->ref_clk = devm_clk_get_optional_enabled(&pdev->dev, NULL); if (IS_ERR(mcspi->ref_clk)) mcspi->ref_clk_hz = OMAP2_MCSPI_MAX_FREQ; else mcspi->ref_clk_hz = clk_get_rate(mcspi->ref_clk); + dev_dbg(&pdev->dev, "DEBUG_EXTRA: ref_clk_hz %d\n", mcspi->ref_clk_hz); ctlr->max_speed_hz = mcspi->ref_clk_hz; ctlr->min_speed_hz = mcspi->ref_clk_hz >> 15;
---8<--- /dts-v1/;
#include "am33xx.dtsi" #include <dt-bindings/interrupt-controller/irq.h> ...
&spi0 { status = "okay"; pinctrl-names = "default"; pinctrl-0 = <&spi0_pins_default>; ti,spi-num-cs = <1>;
flash@0 { compatible = "jedec,spi-nor"; reg = <0>; spi-tx-bus-width = <1>; spi-rx-bus-width = <1>; spi-max-frequency = <10000000>;
partitions { compatible = "fixed-partitions"; #address-cells = <1>; #size-cells = <1>; partition@0 { reg = <0x0 0x1f00000>; label = "radio-program"; }; partition@1f00000 { reg = <0x1f00000 0xe0000>; label = "linux-data"; read-only; }; partition@1fe0000 { reg = <0x1fe0000 0x10000>; label = "radio-config"; read-only; }; partition@1ff0000 { reg = <0x1ff0000 0x10000>; label = "baseband-config"; read-only; }; }; }; };
---8<--- Jan 16 11:30:53 ptxdist kernel: omap2_mcspi 48030000.spi: DEBUG_EXTRA pre calc Jan 16 11:30:54 ptxdist kernel: omap2_mcspi 48030000.spi: DEBUG_EXTRA: ref_clk_hz 0 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi 48030000.spi: registered host spi0 Jan 16 11:30:54 ptxdist kernel: Division by zero in kernel. Jan 16 11:30:54 ptxdist kernel: CPU: 0 UID: 0 PID: 161 Comm: (udev-worker) Not tainted 6.12.8 #1 Jan 16 11:30:54 ptxdist kernel: Hardware name: Generic AM33XX (Flattened Device Tree) Jan 16 11:30:54 ptxdist kernel: Call trace: Jan 16 11:30:54 ptxdist kernel: dump_backtrace from show_stack+0x20/0x38 Jan 16 11:30:54 ptxdist kernel: r7:c4a7ff00 r6:c0cef6bc r5:00000000 r4:600f0113 Jan 16 11:30:54 ptxdist kernel: show_stack from dump_stack_lvl+0x40/0x78 Jan 16 11:30:54 ptxdist kernel: dump_stack_lvl from dump_stack+0x18/0x28 Jan 16 11:30:54 ptxdist kernel: r7:c4a7ff00 r6:00000008 r5:c477dbc0 r4:c4a7ec00 Jan 16 11:30:54 ptxdist kernel: dump_stack from __div0+0x24/0x34 Jan 16 11:30:54 ptxdist kernel: __div0 from Ldiv0+0x8/0x10 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_setup_transfer [spi_omap2_mcspi] from omap2_mcspi_setup+0x134/0x20c [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: r9:c4a7ff28 r8:c477dbd0 r7:c4a7ff00 r6:c4a7ec00 r5:c2572c10 r4:00000001 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_setup [spi_omap2_mcspi] from spi_setup+0x124/0x4f8 Jan 16 11:30:54 ptxdist kernel: r9:c4a7edaf r8:00000000 r7:c2572c10 r6:c4a7fc00 r5:00000000 r4:c4a7ec00 Jan 16 11:30:54 ptxdist kernel: spi_setup from __spi_add_device+0x15c/0x300 Jan 16 11:30:54 ptxdist kernel: r6:c4a7fc00 r5:c4a7ec00 r4:c4a7ed9f Jan 16 11:30:54 ptxdist kernel: __spi_add_device from of_register_spi_devices+0x74/0x1a8 Jan 16 11:30:54 ptxdist kernel: r10:c0fe67cc r9:c4a7fd98 r8:c4a7fdd4 r7:c4a7ec00 r6:c4a7fc00 r5:00000000 Jan 16 11:30:54 ptxdist kernel: r4:cfce0df4 Jan 16 11:30:54 ptxdist kernel: of_register_spi_devices from spi_register_controller+0x3d0/0x4d0 Jan 16 11:30:54 ptxdist kernel: r9:c4a7fd98 r8:c0fe67d4 r7:c4a7fda0 r6:00000000 r5:c0fe67d4 r4:c4a7fc00 Jan 16 11:30:54 ptxdist kernel: spi_register_controller from devm_spi_register_controller+0x54/0xbc Jan 16 11:30:54 ptxdist kernel: r10:bf006108 r9:c2572c10 r8:c4a7fc00 r7:c2572c10 r6:c4a7fc00 r5:c4a7ff00 Jan 16 11:30:54 ptxdist kernel: r4:c46cd2c0 Jan 16 11:30:54 ptxdist kernel: devm_spi_register_controller from omap2_mcspi_probe+0x51c/0x5cc [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: r7:c4a7fc00 r6:c2572c10 r5:c4a7ff00 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_probe [spi_omap2_mcspi] from platform_probe+0x6c/0xd0 Jan 16 11:30:54 ptxdist kernel: r10:d0481ed0 r9:00000001 r8:00000000 r7:c1028ef8 r6:bf004014 r5:c2572c10 Jan 16 11:30:54 ptxdist kernel: r4:00000000 Jan 16 11:30:54 ptxdist kernel: platform_probe from really_probe+0xf0/0x3ec Jan 16 11:30:54 ptxdist kernel: r7:c1028ef8 r6:bf004014 r5:00000000 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: really_probe from __driver_probe_device+0xac/0x13c Jan 16 11:30:54 ptxdist kernel: r8:c27a50b4 r7:0000007d r6:c2572c10 r5:bf004014 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: __driver_probe_device from driver_probe_device+0x40/0xe4 Jan 16 11:30:54 ptxdist kernel: r5:bf004014 r4:c1071d9c Jan 16 11:30:54 ptxdist kernel: driver_probe_device from __driver_attach+0x154/0x204 Jan 16 11:30:54 ptxdist kernel: r7:00000000 r6:c2572c54 r5:bf004014 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: __driver_attach from bus_for_each_dev+0x8c/0xf0 Jan 16 11:30:54 ptxdist kernel: r7:00000000 r6:c20e96c0 r5:c06404ec r4:bf004014 Jan 16 11:30:54 ptxdist kernel: bus_for_each_dev from driver_attach+0x2c/0x44 Jan 16 11:30:54 ptxdist kernel: r7:c20e96c0 r6:00000000 r5:c27a5080 r4:bf004014 Jan 16 11:30:54 ptxdist kernel: driver_attach from bus_add_driver+0x104/0x244 Jan 16 11:30:54 ptxdist kernel: bus_add_driver from driver_register+0x8c/0x164 Jan 16 11:30:54 ptxdist kernel: r8:00000000 r7:bf004100 r6:c101f840 r5:a7ac7714 r4:bf004014 Jan 16 11:30:54 ptxdist kernel: driver_register from __platform_driver_register+0x2c/0x40 Jan 16 11:30:54 ptxdist kernel: r5:a7ac7714 r4:c0fac2fc Jan 16 11:30:54 ptxdist kernel: __platform_driver_register from omap2_mcspi_driver_init+0x38/0x1000 [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_driver_init [spi_omap2_mcspi] from do_one_initcall+0x68/0x2b8 Jan 16 11:30:54 ptxdist kernel: r5:c2a95800 r4:bf008000 Jan 16 11:30:54 ptxdist kernel: do_one_initcall from do_init_module+0x64/0x218 Jan 16 11:30:54 ptxdist kernel: r8:bf004100 r7:bf004100 r6:c477d240 r5:00000000 r4:bf004100 Jan 16 11:30:54 ptxdist kernel: do_init_module from load_module+0x7e4/0xa18 Jan 16 11:30:54 ptxdist kernel: r6:00000000 r5:00000000 r4:00000000 Jan 16 11:30:54 ptxdist kernel: load_module from init_module_from_file+0xa4/0xec Jan 16 11:30:54 ptxdist kernel: r10:c477c080 r9:c1054a48 r8:c477c080 r7:c1054a38 r6:b5b1d7f0 r5:c477c080 Jan 16 11:30:54 ptxdist kernel: r4:00000000 Jan 16 11:30:54 ptxdist kernel: init_module_from_file from sys_finit_module+0x244/0x39c Jan 16 11:30:54 ptxdist kernel: r6:00000001 r5:000000f4 r4:c2a95800 Jan 16 11:30:54 ptxdist kernel: sys_finit_module from __sys_trace_return+0x0/0x10 Jan 16 11:30:54 ptxdist kernel: Exception stack(0xd0481fa8 to 0xd0481ff0) Jan 16 11:30:54 ptxdist kernel: 1fa0: 14cb6a00 00000000 0000001a b5b1d7f0 00000000 00000000 Jan 16 11:30:54 ptxdist kernel: 1fc0: 14cb6a00 00000000 00826358 0000017b 008456d0 b6f75934 b5b1739d 00000000 Jan 16 11:30:54 ptxdist kernel: 1fe0: bee9d538 bee9d528 b5b16643 b6c5d262 Jan 16 11:30:54 ptxdist kernel: r10:0000017b r9:c2a95800 r8:c01002c4 r7:0000017b r6:00826358 r5:00000000 Jan 16 11:30:54 ptxdist kernel: r4:14cb6a00 Jan 16 11:30:54 ptxdist kernel: Division by zero in kernel. Jan 16 11:30:54 ptxdist kernel: CPU: 0 UID: 0 PID: 161 Comm: (udev-worker) Not tainted 6.12.8 #1 Jan 16 11:30:54 ptxdist kernel: Hardware name: Generic AM33XX (Flattened Device Tree) Jan 16 11:30:54 ptxdist kernel: Call trace: Jan 16 11:30:54 ptxdist kernel: dump_backtrace from show_stack+0x20/0x38 Jan 16 11:30:54 ptxdist kernel: r7:c4a7ff00 r6:c0cef6bc r5:00000000 r4:600f0113 Jan 16 11:30:54 ptxdist kernel: show_stack from dump_stack_lvl+0x40/0x78 Jan 16 11:30:54 ptxdist kernel: dump_stack_lvl from dump_stack+0x18/0x28 Jan 16 11:30:54 ptxdist kernel: r7:c4a7ff00 r6:00000008 r5:c477dbc0 r4:c4a7ec00 Jan 16 11:30:54 ptxdist kernel: dump_stack from __div0+0x24/0x34 Jan 16 11:30:54 ptxdist kernel: __div0 from Ldiv0+0x8/0x10 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_setup_transfer [spi_omap2_mcspi] from omap2_mcspi_setup+0x134/0x20c [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: r9:c4a7ff28 r8:c477dbd0 r7:c4a7ff00 r6:c4a7ec00 r5:c2572c10 r4:00000001 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_setup [spi_omap2_mcspi] from spi_setup+0x124/0x4f8 Jan 16 11:30:54 ptxdist kernel: r9:c4a7edaf r8:00000000 r7:c2572c10 r6:c4a7fc00 r5:00000000 r4:c4a7ec00 Jan 16 11:30:54 ptxdist kernel: spi_setup from __spi_add_device+0x15c/0x300 Jan 16 11:30:54 ptxdist kernel: r6:c4a7fc00 r5:c4a7ec00 r4:c4a7ed9f Jan 16 11:30:54 ptxdist kernel: __spi_add_device from of_register_spi_devices+0x74/0x1a8 Jan 16 11:30:54 ptxdist kernel: r10:c0fe67cc r9:c4a7fd98 r8:c4a7fdd4 r7:c4a7ec00 r6:c4a7fc00 r5:00000000 Jan 16 11:30:54 ptxdist kernel: r4:cfce0df4 Jan 16 11:30:54 ptxdist kernel: of_register_spi_devices from spi_register_controller+0x3d0/0x4d0 Jan 16 11:30:54 ptxdist kernel: r9:c4a7fd98 r8:c0fe67d4 r7:c4a7fda0 r6:00000000 r5:c0fe67d4 r4:c4a7fc00 Jan 16 11:30:54 ptxdist kernel: spi_register_controller from devm_spi_register_controller+0x54/0xbc Jan 16 11:30:54 ptxdist kernel: r10:bf006108 r9:c2572c10 r8:c4a7fc00 r7:c2572c10 r6:c4a7fc00 r5:c4a7ff00 Jan 16 11:30:54 ptxdist kernel: r4:c46cd2c0 Jan 16 11:30:54 ptxdist kernel: devm_spi_register_controller from omap2_mcspi_probe+0x51c/0x5cc [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: r7:c4a7fc00 r6:c2572c10 r5:c4a7ff00 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_probe [spi_omap2_mcspi] from platform_probe+0x6c/0xd0 Jan 16 11:30:54 ptxdist kernel: r10:d0481ed0 r9:00000001 r8:00000000 r7:c1028ef8 r6:bf004014 r5:c2572c10 Jan 16 11:30:54 ptxdist kernel: r4:00000000 Jan 16 11:30:54 ptxdist kernel: platform_probe from really_probe+0xf0/0x3ec Jan 16 11:30:54 ptxdist kernel: r7:c1028ef8 r6:bf004014 r5:00000000 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: really_probe from __driver_probe_device+0xac/0x13c Jan 16 11:30:54 ptxdist kernel: r8:c27a50b4 r7:0000007d r6:c2572c10 r5:bf004014 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: __driver_probe_device from driver_probe_device+0x40/0xe4 Jan 16 11:30:54 ptxdist kernel: r5:bf004014 r4:c1071d9c Jan 16 11:30:54 ptxdist kernel: driver_probe_device from __driver_attach+0x154/0x204 Jan 16 11:30:54 ptxdist kernel: r7:00000000 r6:c2572c54 r5:bf004014 r4:c2572c10 Jan 16 11:30:54 ptxdist kernel: __driver_attach from bus_for_each_dev+0x8c/0xf0 Jan 16 11:30:54 ptxdist kernel: r7:00000000 r6:c20e96c0 r5:c06404ec r4:bf004014 Jan 16 11:30:54 ptxdist kernel: bus_for_each_dev from driver_attach+0x2c/0x44 Jan 16 11:30:54 ptxdist kernel: r7:c20e96c0 r6:00000000 r5:c27a5080 r4:bf004014 Jan 16 11:30:54 ptxdist kernel: driver_attach from bus_add_driver+0x104/0x244 Jan 16 11:30:54 ptxdist kernel: bus_add_driver from driver_register+0x8c/0x164 Jan 16 11:30:54 ptxdist kernel: r8:00000000 r7:bf004100 r6:c101f840 r5:a7ac7714 r4:bf004014 Jan 16 11:30:54 ptxdist kernel: driver_register from __platform_driver_register+0x2c/0x40 Jan 16 11:30:54 ptxdist kernel: r5:a7ac7714 r4:c0fac2fc Jan 16 11:30:54 ptxdist kernel: __platform_driver_register from omap2_mcspi_driver_init+0x38/0x1000 [spi_omap2_mcspi] Jan 16 11:30:54 ptxdist kernel: omap2_mcspi_driver_init [spi_omap2_mcspi] from do_one_initcall+0x68/0x2b8 Jan 16 11:30:54 ptxdist kernel: r5:c2a95800 r4:bf008000 Jan 16 11:30:54 ptxdist kernel: do_one_initcall from do_init_module+0x64/0x218 Jan 16 11:30:54 ptxdist kernel: r8:bf004100 r7:bf004100 r6:c477d240 r5:00000000 r4:bf004100 Jan 16 11:30:54 ptxdist kernel: do_init_module from load_module+0x7e4/0xa18 Jan 16 11:30:54 ptxdist kernel: r6:00000000 r5:00000000 r4:00000000 Jan 16 11:30:54 ptxdist kernel: load_module from init_module_from_file+0xa4/0xec Jan 16 11:30:54 ptxdist kernel: r10:c477c080 r9:c1054a48 r8:c477c080 r7:c1054a38 r6:b5b1d7f0 r5:c477c080 Jan 16 11:30:54 ptxdist kernel: r4:00000000 Jan 16 11:30:54 ptxdist kernel: init_module_from_file from sys_finit_module+0x244/0x39c Jan 16 11:30:54 ptxdist kernel: r6:00000001 r5:000000f4 r4:c2a95800 Jan 16 11:30:54 ptxdist kernel: sys_finit_module from __sys_trace_return+0x0/0x10 Jan 16 11:30:54 ptxdist kernel: Exception stack(0xd0481fa8 to 0xd0481ff0) Jan 16 11:30:54 ptxdist kernel: 1fa0: 14cb6a00 00000000 0000001a b5b1d7f0 00000000 00000000 Jan 16 11:30:54 ptxdist kernel: 1fc0: 14cb6a00 00000000 00826358 0000017b 008456d0 b6f75934 b5b1739d 00000000 Jan 16 11:30:55 ptxdist kernel: 1fe0: bee9d538 bee9d528 b5b16643 b6c5d262 Jan 16 11:30:55 ptxdist kernel: r10:0000017b r9:c2a95800 r8:c01002c4 r7:0000017b r6:00826358 r5:00000000 Jan 16 11:30:55 ptxdist kernel: r4:14cb6a00 Jan 16 11:30:55 ptxdist kernel: spi spi0.0: setup: speed 0, sample leading edge, clk normal Jan 16 11:30:55 ptxdist kernel: spi spi0.0: setup mode 0, 8 bits/w, 10000000 Hz max --> 0
On Thu, Jan 16, 2025 at 03:21:13PM +0100, Lars Pedersen wrote:
Hi. We have discovered an SPI regression when upgrading from 6.1.99 to a newer LTS version. Same error on kernel 6.6.71 and 6.12.8.
I think we have identified the problem down to the reference clock calculation that seems to end up to zero in the spi-omap2-mcspi driver.
Also we think it relates to commit 4c6ac5446d060f0bf435ccc8bc3aa7b7b5f718ad, where OMAP2_MCSPI_MAX_FREQ is used as fallback on error. In our case it seems to hit the else case.
Snippets for device tree, spi-omap2-mcspi driver and kernel divide by zero error log with dynamic debug enabled.
If you revert the offending commit, does that solve the issue?
thanks,
greg k-h
On Fri, 17 Jan 2025 at 13:32, Greg KH gregkh@linuxfoundation.org wrote:
On Thu, Jan 16, 2025 at 03:21:13PM +0100, Lars Pedersen wrote:
Hi. We have discovered an SPI regression when upgrading from 6.1.99 to a newer LTS version. Same error on kernel 6.6.71 and 6.12.8.
I think we have identified the problem down to the reference clock calculation that seems to end up to zero in the spi-omap2-mcspi driver.
Also we think it relates to commit 4c6ac5446d060f0bf435ccc8bc3aa7b7b5f718ad, where OMAP2_MCSPI_MAX_FREQ is used as fallback on error. In our case it seems to hit the else case.
Snippets for device tree, spi-omap2-mcspi driver and kernel divide by zero error log with dynamic debug enabled.
If you revert the offending commit, does that solve the issue?
thanks,
greg k-h
Hi Greg.
No it doesn't solve the issue by reverting the commit. The commit isn't the regression, but it attempts to handle it in the if/else statement. Everything starts to work again if we hard code it to "mcspi->ref_clk_hz = OMAP2_MCSPI_MAX_FREQ;", so it seems like the if else statement isn't 100% foolproof (or we have missed a setting in the device tree).
Thanks
/Lars Pedersen
Hi
On Fri, Jan 17, 2025 at 03:49:25PM +0100, Lars Pedersen wrote:
On Fri, 17 Jan 2025 at 13:32, Greg KH gregkh@linuxfoundation.org wrote:
On Thu, Jan 16, 2025 at 03:21:13PM +0100, Lars Pedersen wrote:
Hi. We have discovered an SPI regression when upgrading from 6.1.99 to a newer LTS version. Same error on kernel 6.6.71 and 6.12.8.
We have a very similar regression on the Nokia N900, causing everything on the SPI bus (WLAN, screen) to stop working or be unreliable.
I think we have identified the problem down to the reference clock calculation that seems to end up to zero in the spi-omap2-mcspi driver.
Also we think it relates to commit 4c6ac5446d060f0bf435ccc8bc3aa7b7b5f718ad, where OMAP2_MCSPI_MAX_FREQ is used as fallback on error. In our case it seems to hit the else case.
If you revert the offending commit, does that solve the issue?
thanks,
greg k-h
Hi Greg.
No it doesn't solve the issue by reverting the commit. The commit isn't the regression, but it attempts to handle it in the if/else statement. Everything starts to work again if we hard code it to "mcspi->ref_clk_hz = OMAP2_MCSPI_MAX_FREQ;", so it seems like the if else statement isn't 100% foolproof (or we have missed a setting in the device tree).
The commit actually *is* the regression. The subtle issue causing it is that devm_clk_get_optional_enabled() may also return NULL. In the previous code, the NULL was not considered an error condition. The change to the IS_ERR macro causes the NULL condition to be unhandled, hence it takes the `else` path. Using IS_ERR_OR_NULL restores the previous behavior, since changing it was not the intention of the commit in question.
Please check if the attached patch does not fix it for you, and I can submit it, perhaps with your Tested-by. It does resolve the issue on the Nokia N900, for both WLAN and the screen.
Regards Sicelo
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Lars Pedersen -
Sicelo