Hi Vladimir, On Tuesday 17 November 2015 13:20:40 Vladimir Zapolskiy wrote: > Hi Markus, > > On 17.11.2015 11:24, Markus Pargmann wrote: > > Hi, > > > > On Wednesday 11 November 2015 14:36:53 Vladimir Zapolskiy wrote: > >> Commit c0017ed71966 ("gpio: Introduce gpio descriptor 'name'") causes > >> OOPS on boot on LPC32xx boards: > >> > >> Unable to handle kernel NULL pointer dereference at virtual address > >> 00000000 > >> CPU: 0 PID: 1 Comm: swapper Not tainted 4.3.0+ #707 > >> Hardware name: LPC32XX SoC (Flattened Device Tree) > >> task: c381baa0 ti: c381e000 task.ti: c381e000 > >> PC is at strcmp+0x10/0x40 > >> LR is at gpiochip_add+0x3d0/0x4d4 > >> pc : [<>] lr : [<>] psr: a0000093 > >> sp : c381fd60 ip : c381fd70 fp : c381fd6c > >> > >> [snip] > >> > >> Backtrace: > >> [<>] (strcmp) from [<>] (gpiochip_add+0x3d0/0x4d4) > >> [<>] (gpiochip_add) from [<>] (lpc32xx_gpio_probe+0x44/0x60) > >> [<>] (lpc32xx_gpio_probe) from [<>] (platform_drv_probe+0x40/0x8c) > >> [<>] (platform_drv_probe) from [<>] (driver_probe_device+0x110/0x294) > >> [<>] (driver_probe_device) from [<>] (__driver_attach+0x70/0x94) > >> [<>] (__driver_attach) from [<>] (bus_for_each_dev+0x74/0x98) > >> [<>] (bus_for_each_dev) from [<>] (driver_attach+0x20/0x28) > >> [<>] (driver_attach) from [<>] (bus_add_driver+0xd4/0x1f0) > >> [<>] (bus_add_driver) from [<>] (driver_register+0xa4/0xe8) > >> [<>] (driver_register) from [<>] (__platform_driver_register+0x38/0x4c) > >> [<>] (__platform_driver_register) from [<>] > >> (lpc32xx_gpio_driver_init+0x18/0x20) > >> [<>] (lpc32xx_gpio_driver_init) from [<>] (do_one_initcall+0x108/0x1c8) > >> [<>] (do_one_initcall) from [<>] (kernel_init_freeable+0x10c/0x1d4) > >> [<>] (kernel_init_freeable) from [<>] (kernel_init+0x10/0xec) > >> [<>] (kernel_init) from [<>] (ret_from_fork+0x14/0x24) > >> > >> This is caused by the fact that at the moment some GPIO names are set > >> to NULL, there is a hole in linear representation of one GPI bank, see > >> drivers/gpio/gpio-lpc32xx.c / gpi_p3_names[] for details. > >> > >> The same problem most probably affects also gpio-cs5535.c, see > >> cs5535_gpio_names[]. > >> > >> Signed-off-by: Vladimir Zapolskiy <v...@mleia.com> > >> --- > >> Linus, Markus, > >> > >> I understand that LPC32xx GPIO driver is ugly (hopefully this > >> will be changed in future), but please account this problem. > >> > >> I don't ask for inclusion of this change, because my own analysis is > >> not done completely. > >> > >> Also please review, the same problem probably affects gpio-cs5535.c > >> as well, see cs5535_gpio_names[]. > > > > Thanks for this hint. But I think these patches for gpio_name_to_desc won't > > get > > mainline any time soon as this depends on the chardev interface and how it > > will > > look like. > > > > sorry for misunderstanding, what do mean by "these patches"? > > I see two options here, one is to fix or revert your c0017ed71966 due to > caused regressions, another one is to update affected GPIO drivers > removing discontinuity in GPIO enumeration inside a bank.
Sorry, seems I was on a wrong kernel version when checking this morning. Linus removed lots of my patches from his tree after some correct comments so I thought this patch was removed as well. As it is mainline your patch looks good to me. Perhaps a comment on why we need to check for !name at this point would be good. Best Regards, Markus > > With best wishes, > Vladimir > > >> > >> drivers/gpio/gpiolib.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > >> index a18f00f..2a91f32 100644 > >> --- a/drivers/gpio/gpiolib.c > >> +++ b/drivers/gpio/gpiolib.c > >> @@ -233,7 +233,7 @@ static struct gpio_desc *gpio_name_to_desc(const char > >> * const name) > >> for (i = 0; i != chip->ngpio; ++i) { > >> struct gpio_desc *gpio = &chip->desc[i]; > >> > >> - if (!gpio->name) > >> + if (!gpio->name || !name) > >> continue; > >> > >> if (!strcmp(gpio->name, name)) { > >> > > > -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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