linux-kernel - Re: [RESEND PATCH v2] mfd: twl6030: Fix endianness problem in IRQ handler

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Date:	Mon, 23 Dec 2013 19:47:57 +0200
From:	Taras Kondratiuk <taras.kondratiuk@...aro.org>
To:	Joe Perches <joe@...ches.com>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Patch Tracking <patches@...aro.org>,
	Linaro Networking <linaro-networking@...aro.org>,
	Linaro Kernel <linaro-kernel@...ts.linaro.org>,
	Danke Xie <d.xie@....samsung.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2] mfd: twl6030: Fix endianness problem in IRQ handler

On 23 December 2013 19:20, Joe Perches <joe@...ches.com> wrote:
> On Mon, 2013-12-23 at 19:11 +0200, Taras Kondratiuk wrote:
>> From: Danke Xie <d.xie@....samsung.com>
>>
>> The current TWL 6030 IRQ handler assumes little endianness.
>> This change makes it endian-neutral.
> []
>> diff --git a/drivers/mfd/twl6030-irq.c b/drivers/mfd/twl6030-irq.c
> []
>> @@ -196,8 +197,9 @@ static irqreturn_t twl6030_irq_thread(int irq, void *data)
>>       if (sts.bytes[2] & 0x10)
>>               sts.bytes[2] |= 0x08;
>>
>> -     for (i = 0; sts.int_sts; sts.int_sts >>= 1, i++)
>> -             if (sts.int_sts & 0x1) {
>> +     int_sts = le32_to_cpu(sts.int_sts);
>> +     for (i = 0; int_sts; int_sts >>= 1, i++)
>> +             if (int_sts & 0x1) {
>>                       int module_irq =
>>                               irq_find_mapping(pdata->irq_domain,
>>                                                pdata->irq_mapping_tbl[i]);
>
> instead of the
>
>         for (...) {
>                 if (foo & 1) {
>
>
> maybe using ffs would be better/faster
>
>         while ((bit = ffs(int_sts))) {
>
> etc...

Makes sense, but the aim of this patch is to fix endianness issue.
This micro-optimisation can be done as a separate patch.

-- 
Regards,
Taras Kondratiuk
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