linux-kernel - Re: [PATCH 2/2] adm8211: fix the possible pci cache line sizes inside switch-case

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Message-Id: <2CBE2DDF-92E5-45C9-95F8-C5CF918D12D9@gmail.com>
Date:	Mon, 11 May 2015 09:48:54 +0100
From:	Okash Khawaja <okash.khawaja@...il.com>
To:	Kalle Valo <kvalo@...eaurora.org>
Cc:	"joe@...ches.com" <joe@...ches.com>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] adm8211: fix the possible pci cache line sizes inside switch-case


> On 11 May 2015, at 07:30, Kalle Valo <kvalo@...eaurora.org> wrote:
> 
> Okash Khawaja <okash.khawaja@...il.com> writes:
> 
>>> On Wed, May 06, 2015 at 07:59:04AM +0300, Kalle Valo wrote:
>>> Okash Khawaja <okash.khawaja@...il.com> writes:
>>> 
>>>> The PCI cache line size value was being compared against decimal
>>>> values prefixed with 0x.
>>>> Fixed the literals to use the correct hex values.
>>>> 
>>>> Signed-off-by: Okash Khawaja <okash.khawaja@...il.com>
>>> [...]
>>> 
>>>> @@ -1101,10 +1101,10 @@ static void adm8211_hw_init(struct
>>>> ieee80211_hw *dev) case 0x8: reg |= (0x1 << 14); break; - case
>>>> 0x16: + case 0x10: reg |= (0x2 << 14); break; - case 0x32: + case
>>>> 0x20: reg |= (0x3 << 14); break; default:
>>> Did you test this? How certain can we be that this doesn't break
>>> anything?
>> 
>> I didn't test it as that would require the hardware that I don't have
>> at the moment. However, the value in `cline` is PCI cache line size,
>> which is the CPU's cache line size. It is less likely for cache line
>> sizes to be 22 or 50, and more likely for them to be 16 or 32. Also,
>> as far as I understand (and I might be wrong here), cache line size is
>> used for things like aligning DMA requests with CPU cache line, which
>> improve performance but wouldn't break anything if the value doesn't
>> match. In this case, we will fall through to the default case which
>> leaves `reg` unchanged.
>> 
>> If there is a way to test it with a mock set up or if you still think
>> we need to test this on real board, I'll be happy to try get the
>> hardware. But I will need some guidance around that. Thanks.
> 
> I don't have any ideas how to test this as I think the hardware is
> pretty rare nowadays but I think this is safe to commit, thanks for
> clearing this up. BTW, what you wrote about would have been perferct in
> the commit log itself.
> 
> -- 
> Kalle Valo

Sure, I'll create v2 of the patch with updated commit log. 

Since it's part of a patch set, do you want me to send both the patches in the patch set together as v2 or just this patch? 

Thanks--
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