Re: [PATCH v5 3/3] gpiolib: Show correct direction from the beginning

[Vignesh R <vigneshr@xxxxxx>]

Hi,

On Friday 05 October 2018 12:23 PM, Ricardo Ribalda Delgado wrote:
> Current code assumes that the direction is input if direction_input
> function is set.
> This might not be the case on GPIOs with programmable direction.
> 
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx>
> Tested-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>

This patch causes oops on TI's AM335x-ICEv2 board on next-20181011:

[    0.563797] OMAP GPIO hardware version 0.1
[    0.577589] Unable to handle kernel NULL pointer dereference at virtual address 000002b8
[    0.586127] pgd = (ptrval)
[    0.588934] [000002b8] *pgd=00000000
[    0.592732] Internal error: Oops: 5 [#1] SMP ARM
[    0.597499] Modules linked in:
[    0.600668] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc7-next-20181011 #70
[    0.608466] Hardware name: Generic AM33XX (Flattened Device Tree)
[    0.614770] PC is at gpiod_hog+0x30/0x154
[    0.618913] LR is at of_gpiochip_add+0x2fc/0x4e4
[    0.623671] pc : [<c055213c>]    lr : [<c0553ff0>]    psr: 60000013
[    0.630130] sp : ce09bba0  ip : cdf08095  fp : 00000000
[    0.635516] r10: c0bfcf24  r9 : 00000000  r8 : 00000007
[    0.640902] r7 : cdf08088  r6 : 00000000  r5 : 00000000  r4 : ce191e40
[    0.647630] r3 : 00000000  r2 : 00000000  r1 : cdf08088  r0 : ce191e40
[    0.654361] Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[    0.661718] Control: 10c5387d  Table: 80004019  DAC: 00000051
[    0.667642] Process swapper/0 (pid: 1, stack limit = 0x(ptrval))
[...]
[    0.973593] [<c055213c>] (gpiod_hog) from [<c0553ff0>] (of_gpiochip_add+0x2fc/0x4e4)
[    0.981588] [<c0553ff0>] (of_gpiochip_add) from [<c05528a0>] (gpiochip_add_data_with_key+
0x5a0/0x990)
[    0.991102] [<c05528a0>] (gpiochip_add_data_with_key) from [<c0556d8c>] (omap_gpio_probe+
0x37c/0x75c)
[    1.000613] [<c0556d8c>] (omap_gpio_probe) from [<c06049c0>] (platform_drv_probe+0x48/0x9
8)
[    1.009237] [<c06049c0>] (platform_drv_probe) from [<c0602a04>] (really_probe+0x220/0x2d4
)
[    1.017764] [<c0602a04>] (really_probe) from [<c0602c18>] (driver_probe_device+0x5c/0x164
)
[    1.026293] [<c0602c18>] (driver_probe_device) from [<c0600d44>] (bus_for_each_drv+0x54/0
xb8)
[    1.035090] [<c0600d44>] (bus_for_each_drv) from [<c060276c>] (__device_attach+0xcc/0x13c
)
[    1.043615] [<c060276c>] (__device_attach) from [<c0601b88>] (bus_probe_device+0x88/0x90)
[    1.052051] [<c0601b88>] (bus_probe_device) from [<c05fea18>] (device_add+0x3d8/0x608)
[    1.060223] [<c05fea18>] (device_add) from [<c07343b8>] (of_platform_device_create_pdata+
0x8c/0xc0)
[    1.069552] [<c07343b8>] (of_platform_device_create_pdata) from [<c07345c4>] (of_platform
_bus_create+0x190/0x228)
[    1.080134] [<c07345c4>] (of_platform_bus_create) from [<c0734610>] (of_platform_bus_crea
te+0x1dc/0x228)
[    1.089909] [<c0734610>] (of_platform_bus_create) from [<c073478c>] (of_platform_populate
+0x5c/0xac)
[    1.099333] [<c073478c>] (of_platform_populate) from [<c0d12614>] (pdata_quirks_init+0x6c
/0x90)
[    1.108306] [<c0d12614>] (pdata_quirks_init) from [<c0d12144>] (omap_generic_init+0xc/0x1
8)
[    1.116933] [<c0d12144>] (omap_generic_init) from [<c0d03eb0>] (customize_machine+0x1c/0x
30)
[    1.125645] [<c0d03eb0>] (customize_machine) from [<c01030e4>] (do_one_initcall+0x80/0x31
0)
[    1.134265] [<c01030e4>] (do_one_initcall) from [<c0d01244>] (kernel_init_freeable+0x3c4/
0x4ac)
[    1.143238] [<c0d01244>] (kernel_init_freeable) from [<c0900f28>] (kernel_init+0x8/0x114)
[    1.151673] [<c0900f28>] (kernel_init) from [<c01010b4>] (ret_from_fork+0x14/0x20)
[    1.159475] Exception stack(0xce09bfb0 to 0xce09bff8)
[    1.164686] bfa0:                                     00000000 00000000 00000000 00000000
[    1.173119] bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    1.181551] bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    1.188378] Code: 0a000002 e3530000 01a09003 159392b4 (e59352b8) 
[    1.194766] ---[ end trace d5c17cd400f50a22 ]---
[    1.199606] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    1.199606] 
[    1.209052] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000
00b
[    1.209052]  ]---
[    3.172292] random: fast init done

Full log: https://pastebin.ubuntu.com/p/jG8nN6CTBP/

Reverting this patch from linux-next allows to boot to prompt.

Regards
Vignesh

> ---
>  drivers/gpio/gpiolib.c | 27 +++++++++++++--------------
>  1 file changed, 13 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 907019b67a58..e016b22658ff 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1349,20 +1349,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
>  
>  	spin_unlock_irqrestore(&gpio_lock, flags);
>  
> -	for (i = 0; i < chip->ngpio; i++) {
> -		struct gpio_desc *desc = &gdev->descs[i];
> -
> -		desc->gdev = gdev;
> -
> -		/* REVISIT: most hardware initializes GPIOs as inputs (often
> -		 * with pullups enabled) so power usage is minimized. Linux
> -		 * code should set the gpio direction first thing; but until
> -		 * it does, and in case chip->get_direction is not set, we may
> -		 * expose the wrong direction in sysfs.
> -		 */
> -		desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0;
> -	}
> -
>  #ifdef CONFIG_PINCTRL
>  	INIT_LIST_HEAD(&gdev->pin_ranges);
>  #endif
> @@ -1391,6 +1377,19 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
>  	if (status)
>  		goto err_remove_chip;
>  
> +	for (i = 0; i < chip->ngpio; i++) {
> +		struct gpio_desc *desc = &gdev->descs[i];
> +
> +		desc->gdev = gdev;
> +
> +		if (chip->get_direction && gpiochip_line_is_valid(chip, i))
> +			desc->flags = !chip->get_direction(chip, i) ?
> +					(1 << FLAG_IS_OUT) : 0;
> +		else
> +			desc->flags = !chip->direction_input ?
> +					(1 << FLAG_IS_OUT) : 0;
> +	}
> +
>  	acpi_gpiochip_add(chip);
>  
>  	machine_gpiochip_add(chip);
>