linux-kernel - Re: [PATCH v5 2/3] net: Add Keystone NetCP ethernet driver

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Message-ID: <5429BAD0.1050101@ti.com>
Date:	Mon, 29 Sep 2014 16:02:24 -0400
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	David Miller <davem@...emloft.net>
CC:	<netdev@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <robh+dt@...nel.org>,
	<grant.likely@...aro.org>, <devicetree@...r.kernel.org>,
	<sandeep_n@...com>, <joe@...ches.com>
Subject: Re: [PATCH v5 2/3] net: Add Keystone NetCP ethernet driver

On Monday 29 September 2014 03:52 PM, David Miller wrote:
> From: Santosh Shilimkar <santosh.shilimkar@...com>
> Date: Thu, 25 Sep 2014 13:48:36 -0400
> 
>> +static inline int gbe_phy_link_status(struct gbe_slave *slave)
>> +{
>> +	if (!slave->phy)
>> +		return 1;
>> +
>> +	if (slave->phy->link)
>> +		return 1;
>> +
>> +	return 0;
>> +}
> 
> Please use 'bool' as the return type and return 'true' or 'false'.
> 
ok

> Do not use 'inline' in foo.c files, let the compiler decide.  Please
> audit this entire submission for this problem.
>
ok.
 
>> +static int gbe_port_reset(struct gbe_slave *slave)
>> +{
>> +	u32 i, v;
>> +
>> +	/* Set the soft reset bit */
>> +	writel_relaxed(SOFT_RESET, GBE_REG_ADDR(slave, emac_regs, soft_reset));
> 
> This driver seems to use relaxed readl and writel for almost everything.
> 
> That absolutely cannot be right.  For example, here, you depend upon the
> ordering of this writel_relaxed() to reset the chip relative to the
> real_relaxed() you subsequently do to check ths bits.
> 
> I seriously think that *_relaxed() should only be done in very special
> circumstances where 1) the performance matters and 2) the validity of
> the usage has been put under a microscope and fully documented with huge
> comments above the *_relaxed() calls.
> 
> If you cannot reduce and properly document the really necessary *_relaxed()
> uses, just convert them all to non-_relaxed() for now.
> 
We can stick to non-*relaxed() versions. No problems here.

> I'm also warning you ahead of time that since nobody else seems to feel
> like reviewing this enormous submission, you are going to have to get used
> to me pushing back on these changes over and over for small things like
> coding style and structural/API issues until some reviews it on a higher
> level.
>
> I really don't want to apply this series until someone thinks seriously
> about the driver's design and the long term ramifications of having a
> driver like this in the tree with so many random TX etc. hooks.
> 
The driver has been on the list. Jamal and you have given your comments,
suggestion and we have incorporated that. What else we can do ?

We are badly missing mainline network driver support for the Keystone
and hence I request you to help here.

regards,
Santosh
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