linux-kernel - Re: [PATCH] pinctrl/samsung: Correct EINTG banks order

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Date:   Tue, 10 Apr 2018 17:38:29 +0900
From:   Tomasz Figa <tomasz.figa@...il.com>
To:     Krzysztof Kozlowski <krzk@...nel.org>,
        Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
Cc:     Sylwester Nawrocki <s.nawrocki@...sung.com>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        Kukjin Kim <kgene@...nel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:SAMSUNG SOC CLOCK DRIVERS" 
        <linux-samsung-soc@...r.kernel.org>, linux-gpio@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH] pinctrl/samsung: Correct EINTG banks order

2018-04-10 16:06 GMT+09:00 Krzysztof Kozlowski <krzk@...nel.org>:
> On Sun, Apr 8, 2018 at 8:07 PM, Paweł Chmiel
> <pawel.mikolaj.chmiel@...il.com> wrote:
>> All banks with GPIO interrupts should be at beginning
>> of bank array and without any other types of banks between them.
>> This order is expected by exynos_eint_gpio_irq, when doing
>> interrupt group to bank translation.
>> Otherwise, kernel NULL pointer dereference would happen
>> when trying to handle interrupt, due to wrong bank being looked up.
>> Observed on s5pv210, when trying to handle gpj0 interrupt,
>> where kernel was mapping it to gpi bank.
>
> Thanks for the patch. The issue looks real although one thing was
> missed - there is a gap in SVC group between GPK2 and GPL0 (pointed by
> Marek Szyprowski):
>
> 0x0 - EINT_23 - gpk0
> 0x1 - EINT_24 - gpk1
> 0x2 - EINT_25 - gpk2
> 0x4 - EINT_27 - gpl0
> 0x7 - EINT_8 - gpm0
>
> Maybe this should be done differently - to remove such hidden
> requirement entirely in favor of another parameter of
> EXYNOS_PIN_BANK_EINTG argument?

Perhaps let's limit this patch to s5pv210 and Exynos5410 alone, where
a simple swap of bank order in the arrays should be okay.

We might also need to have some fixes on 4x12, because I noticed that
in exynos4x12_pin_banks0[] there is a hole in eint_offsets between
gpd1 and gpf0 and exynos4x12_pin_banks1[] starts with gpk0 that has
eint_offset equal to 0x08 (not 0).

> Anyway if such hidden requirement
> stays, then please document it in the source code (it maybe next to
> PIN order... or next macro... or also in exynos_eint_gpio_irq()).
>
> Beside that please add cc-stable and appropriate fixes tag,

Agreed. Probably the only safe way of documenting this is to put it
inside each bank array, so that when someone creates a copy/paste for
new SoC, the comment is clearly visible... Perhaps something like:

/* Must start with EINTG banks, ordered by EINT group number. */

Best regards,
Tomasz