From: Alexander Stein <alexander.stein@systec-electronic.com>
To: mrpace2@gmail.com
Cc: linux-gpio@vger.kernel.org
Subject: Re: [PATCH] gpio: gpio-pca953x: no interrupts with 4-bit devices
Date: Wed, 09 Mar 2016 14:05:32 +0100 [thread overview]
Message-ID: <2550700.ucYhgAiWGF@ws-stein> (raw)
In-Reply-To: <emac54c752-04e5-4445-a05e-e6d24a098066@t410-5a>
On Wednesday 09 March 2016 12:37:09, mrpace2@gmail.com wrote:
> I/O expanders with less than 8 I/O (PCA9536 and PCA9537, currently) fail
> to invoke interrupt handlers because the NBANK macro
>
> #define NBANK(chip) (chip->gpio_chip.ngpio / BANK_SZ)
> incorrectly calculates no banks for these devices. As a result,
> pca953x_irq_pending() never sets the trigger_seen flag.
>
> The patch below fixed the issue by changing the NBANK() macro.
>
> Signed-off-by: Frank Edelhaeuser <mrpace2 <at> gmail.com>
> ---
> diff -Nur a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
> --- a/drivers/gpio/gpio-pca953x.c 2016-03-08 00:00:00.000000000 +0000
> +++ b/drivers/gpio/gpio-pca953x.c 2016-03-08 00:00:00.000000000 +0000
> @@ -86,7 +86,7 @@
> #define MAX_BANK 5
> #define BANK_SZ 8
>
> -#define NBANK(chip) (chip->gpio_chip.ngpio / BANK_SZ)
> +#define NBANK(chip) (((chip->gpio_chip.ngpio - 1) / BANK_SZ) + 1)
If ngpio is 0 (e.g. wrong platform device) this underflows and gets a completly wrong result. But I see more of those "ngpio - 1" all over the place.
What about?
> #define NBANK(chip) (((chip->gpio_chip.ngpio + (BANK_SZ - 1)) / BANK_SZ))
Best regards,
Alexander
next prev parent reply other threads:[~2016-03-09 13:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-09 12:37 [PATCH] gpio: gpio-pca953x: no interrupts with 4-bit devices mrpace2
2016-03-09 13:05 ` Alexander Stein [this message]
2016-03-10 10:15 ` [PATCH v2] " mrpace2
2016-03-10 18:02 ` Grygorii Strashko
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