linux-kernel - Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800 Ethernet controller

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Message-ID: <CAHp75VfsswYAvkkkHuaEvkTAgZhoGZQ1oQ_R9BwZgyZ3xRVDeg@mail.gmail.com>
Date:	Wed, 11 Nov 2015 00:40:53 +0200
From:	Andy Shevchenko <andy.shevchenko@...il.com>
To:	Måns Rullgård <mans@...sr.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>, slash.tmp@...e.fr
Subject: Re: [PATCH v5] net: ethernet: add driver for Aurora VLSI NB8800
 Ethernet controller

On Wed, Nov 11, 2015 at 12:34 AM, Måns Rullgård <mans@...sr.com> wrote:
> Andy Shevchenko <andy.shevchenko@...il.com> writes:
>
>>> +static inline void nb8800_maskb(struct nb8800_priv *priv, int reg,
>>> +                               u32 mask, u32 val)
>>> +{
>>> +       u32 old = nb8800_readb(priv, reg);
>>> +       u32 new = (old & ~mask) | val;
>>
>> Shoudn't be "… | (val & mask);" ?
>
> No, it's meant to replace the bits in mask with the corresponding bits
> from val.

But you unconditionally use entire val value which might bring bits
outside of mask.

>> Block comments usually
>> /*
>>  * text
>>  */
>
> Documentation/CodingStyle says net/ and drivers/net/ are special, though
> currently a mix of styles can be found.  Personally, I don't
> particularly care.

OK.

>>> +       nb8800_writel(priv, NB8800_TX_DESC_ADDR, txb->dma_desc);
>>> +       wmb();          /* ensure desc addr is written before starting DMA */
>>
>> Hm… Have I missed corresponding rmb() ? If it's about MMIO, perhaps mmiowb() ?
>
> Possibly.

Standalone wmb() doesn't make sense.

-- 
With Best Regards,
Andy Shevchenko
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