linux-kernel - Re: [PATCH 1/2 v2] Driver for Freescale 8610 and 5121 DIU

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Message-ID: <47E3DE6E.2050801@freescale.com>
Date:	Fri, 21 Mar 2008 11:12:30 -0500
From:	Timur Tabi <timur@...escale.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	York Sun <yorksun@...escale.com>, linux-kernel@...r.kernel.org,
	linuxppc-dev@...abs.org, galak@...nel.crashing.org,
	linux-fbdev-devel@...ts.sourceforge.net,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 1/2 v2] Driver for Freescale 8610 and 5121 DIU

Andrew Morton wrote:

>> +static struct diu_hw dr = {
>> +	.mode = MFB_MODE1,
>> +	.reg_lock = __SPIN_LOCK_UNLOCKED(old_style_spin_init),
>> +};
> 
> I'm not clear on what's supposed to happen with __SPIN_LOCK_UNLOCKED().  I
> do know that its documentation is crap.

Yes, "__SPIN_LOCK_UNLOCKED(old_style_spin_init)" is wrong.  We'll fix it.

>  static struct diu_hw dr = {
>  	.mode = MFB_MODE1,
> -	.reg_lock = __SPIN_LOCK_UNLOCKED(old_style_spin_init),
> +	.reg_lock = __SPIN_LOCK_UNLOCKED(diu_hw.reg_lock),
>  };

Yes, this is better.  Did you already make this change when you applied it to
your -mm repo?

> GFP_DMA implies GFP_ATOMIC, but it's appropriate for documentation purposes.

So does that mean that "GFP_DMA | GFP_KERNEL" is always wrong?  If so, this
combination is used a lot in the kernel today.

>> +	if (virt) {
>> +		*phys = virt_to_phys(virt);
>> +		pr_debug("virt %p, phys=%llx\n", virt, (uint64_t) *phys);
>> +		memset(virt, 0, size);
> 
> Could have used __GFP_ZERO, I guess.

I had completely forgotten about __GFP_ZERO.  Thanks.

>> +	virt = (void *) rh_alloc(&diu_ops.diu_rh_info, size, "DIU");
> 
> hm, I'd have expected checkpatch to whine about the space after the cast
> there.  Whatever.

I thought a space after a cast is the right thing to do?

> please take a look, and please use checkpatch on all future patches.

Sorry, we forgot to run it again after our second version of the patch.

>> +static void free_irq_local(int irq)
>> +{
>> +	struct diu *hw = dr.diu_reg;
>> +
>> +	/* Disable all LCDC interrupt */
>> +	out_be32(&(hw->int_mask), 0x1f);
>> +
>> +	free_irq(irq, 0);
>> +}
> 
> and the free_irq() will go splat?

Sorry, but I don't understand what's wrong with this code.

We'll make the other changes you've suggested and repost.

-- 
Timur Tabi
Linux kernel developer at Freescale
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