From: grinberg@compulab•co.il (Igor Grinberg)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: OMAP2+: ads7846 init: fix fault caused by freeing pen-down GPIO
Date: Mon, 23 Jul 2012 15:53:33 +0300 [thread overview]
Message-ID: <500D494D.8020606@compulab.co.il> (raw)
In-Reply-To: <1342048700-15040-1-git-send-email-khilman@ti.com>
On 07/12/12 02:18, Kevin Hilman wrote:
> commit 97ee9f01d6 (ARM: OMAP: fix the ads7846 init code) mistakenly
> frees the pen-down GPIO even though it will be used by the ads7846
> driver.
But the driver requests the GPIO in ads7846_setup_pendown() method...
>
> Freeing a GPIO means that the GPIO bank containing that GPIO can be
> runtime suspended if its the last/only GPIO being used in that bank.
> If the GPIO bank is runtime suspended, any accesses to that bank will
> cause faults.
Unless, it is requested again, or am I missing something?
>
> Because the current code frees the GPIO, the ads7846 driver probe will
> fault when it requests its IRQ line.
But it requests that GPIO... in ads7846_setup_pendown()
prior to requesting the IRQ...
> Because the IRQ is a GPIO line,
> the request IRQ will trickle down into the OMAP GPIO layer:
> gpio_irq_type() --> _set_gpio_triggering() which can fault if the
> bank has been runtime suspended.
>
> This is exctly what happens on Overo platforms (3530 Water, 3730 Overo
> FireSTORM) since this is the only GPIO used in the bank.
>
> To fix, don't free the GPIO at all since it is always in use.
>
> Cc: Igor Grinberg <grinberg@compulab•co.il>
> Signed-off-by: Kevin Hilman <khilman@ti•com>
> ---
> Tony, this applies on top of your current fixes-non-critical branch and
> should probably go in to v3.5-rc since the patch which introduced the
> problem did as well.
>
> arch/arm/mach-omap2/common-board-devices.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/common-board-devices.c b/arch/arm/mach-omap2/common-board-devices.c
> index c187586..1ae6fd6 100644
> --- a/arch/arm/mach-omap2/common-board-devices.c
> +++ b/arch/arm/mach-omap2/common-board-devices.c
> @@ -84,9 +84,6 @@ void __init omap_ads7846_init(int bus_num, int gpio_pendown, int gpio_debounce,
> ads7846_config.gpio_pendown = gpio_pendown;
> }
>
> - if (!board_pdata || (board_pdata && !board_pdata->get_pendown_state))
> - gpio_free(gpio_pendown);
> -
> spi_register_board_info(&ads7846_spi_board_info, 1);
> }
> #else
--
Regards,
Igor.
next prev parent reply other threads:[~2012-07-23 12:53 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-11 23:18 [PATCH] ARM: OMAP2+: ads7846 init: fix fault caused by freeing pen-down GPIO Kevin Hilman
2012-07-23 12:53 ` Igor Grinberg [this message]
2012-07-23 13:18 ` Igor Grinberg
2012-07-26 19:30 ` Kevin Hilman
2012-07-26 21:19 ` zumeng.chen
2012-07-26 21:58 ` Kevin Hilman
2012-07-26 22:40 ` zumeng.chen
2012-07-27 5:02 ` Zumeng Chen
2012-07-27 15:30 ` Igor Grinberg
2012-07-27 17:46 ` Kevin Hilman
2012-07-27 19:04 ` Igor Grinberg
2012-07-28 0:28 ` Kevin Hilman
2012-08-06 20:22 ` [PATCH] Revert "ARM: OMAP3530evm: set pendown_state and debounce time for ads7846" Igor Grinberg
2012-08-06 20:52 ` Kevin Hilman
2012-08-07 1:44 ` Zumeng Chen
2012-08-07 5:58 ` Igor Grinberg
2012-08-07 10:58 ` Tony Lindgren
2012-08-07 1:42 ` Zumeng Chen
2012-08-07 6:05 ` Igor Grinberg
2012-07-27 18:58 ` [PATCH] ARM: OMAP2+: ads7846 init: fix fault caused by freeing pen-down GPIO Igor Grinberg
2012-07-27 19:05 ` Kevin Hilman
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