patch "iio: adc: vf610_adc: Fix division by zero error" added to staging-linus

This is a note to let you know that I've just added the patch titled

iio: adc: vf610_adc: Fix division by zero error

to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From: Sanchayan Maity <[email protected]>
Date: Mon, 19 Oct 2015 13:13:52 +0530
Subject: iio: adc: vf610_adc: Fix division by zero error

In case the fsl,adck-max-frequency property is not present in the device tree, a division by zero error results during the probe call on kernel boot (see below). This patch fixes it and also restores device tree compatibility in case kernels are booting with old device trees without this property specified.

[    1.063229] Division by zero in kernel.
[    1.067152] CPU: 0 PID: 1 Comm: swapper Not tainted
4.3.0-rc5-00212-gcc88cef #37
[    1.074650] Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)
[    1.081135] Backtrace:
[    1.083694] [<800134a4>] (dump_backtrace) from [<8001369c>]
(show_stack+0x18/0x1c)
[    1.091340]  r7:00000008 r6:8e0ae210 r5:00000000 r4:8e299800
[    1.097146] [<80013684>] (show_stack) from [<80297b1c>]
(dump_stack+0x24/0x28)
[    1.104483] [<80297af8>] (dump_stack) from [<80013608>]
(__div0+0x1c/0x20)
[    1.111421] [<800135ec>] (__div0) from [<802968b4>] (Ldiv0+0x8/0x10)
[    1.117865] [<80424350>] (vf610_adc_probe) from [<803153b4>]
(platform_drv_probe+0x4c/0xac)
[    1.126311]  r10:00000000 r9:8076a5ec r8:00000000 r7:fffffdfb
r6:807cc67c r5:8e0ae210
[    1.134319]  r4:807f6c54
[    1.136915] [<80315368>] (platform_drv_probe) from [<803138bc>]
(driver_probe_device+0x20c/0x2f8)
[    1.145882]  r7:807cc67c r6:00000000 r5:8e0ae210 r4:807f6c54
[    1.151657] [<803136b0>] (driver_probe_device) from [<80313a3c>]
(__driver_attach+0x94/0x98)
[    1.160190]  r9:8076a5ec r8:00000098 r7:00000000 r6:8e0ae244
r5:807cc67c r4:8e0ae210
[    1.168112] [<803139a8>] (__driver_attach) from [<80311cb8>]
(bus_for_each_dev+0x70/0xa4)
[    1.176383]  r7:00000000 r6:803139a8 r5:807cc67c r4:00000000
[    1.182159] [<80311c48>] (bus_for_each_dev) from [<80313318>]
(driver_attach+0x24/0x28)
[    1.190260]  r6:807bb568 r5:8e2a5b00 r4:807cc67c
[    1.194996] [<803132f4>] (driver_attach) from [<80312f50>]
(bus_add_driver+0x1a4/0x21c)
[    1.203113] [<80312dac>] (bus_add_driver) from [<803142a8>]
(driver_register+0x80/0x100)
[    1.211275]  r7:8e2a7dc0 r6:807a8160 r5:80789e14 r4:807cc67c
[    1.217075] [<80314228>] (driver_register) from [<803152f8>]
(__platform_driver_register+0x5c/0x64)
[    1.226216]  r5:80789e14 r4:807a8160
[    1.229877] [<8031529c>] (__platform_driver_register) from
[<80789e30>] (vf610_adc_driver_init+0x1c/0x20)
[    1.239556] [<80789e14>] (vf610_adc_driver_init) from [<800095f8>]
(do_one_initcall+0x94/0x1dc)
[    1.248365] [<80009564>] (do_one_initcall) from [<8076ae34>]
(kernel_init_freeable+0x13c/0x1e0)
[    1.257155]  r10:80794830 r9:8076a5ec r8:00000098 r7:807d5780
r6:807d5780 r5:00000006
[    1.265153]  r4:807a0ee8
[    1.267753] [<8076acf8>] (kernel_init_freeable) from [<80590ef0>]
(kernel_init+0x18/0xf0)
[    1.276021]  r10:00000000 r9:00000000 r8:00000000 r7:00000000
r6:00000000 r5:80590ed8
[    1.284015]  r4:807d5780
[    1.286615] [<80590ed8>] (kernel_init) from [<8000f878>]
(ret_from_fork+0x14/0x3c)
[    1.294278]  r5:80590ed8 r4:00000000

---
 drivers/iio/adc/vf610_adc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 42d7c87ea5be..d937df4f7f2b 100644
@@ -200,6 +200,8 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
 		adc_feature->clk_div = 8;
 	}
 
+	adck_rate = ipg_rate / adc_feature->clk_div;
+
 	/*
 	 * Determine the long sample time adder value to be used based
 	 * on the default minimum sample time provided.

@@ -224,7 +226,6 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
 	 * BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
 	 * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
 	 */
-	adck_rate = ipg_rate / info->adc_feature.clk_div;
 	for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
 		info->sample_freq_avail[i] =
 			adck_rate / (6 + vf610_hw_avgs[i] *

2.6.2