linux-kernel - Re: [PATCH v2] wait while adding MMC host to ensure root mounts

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Date:	Wed, 27 Mar 2013 07:57:34 -0400
From:	Chris Ball <cjb@...top.org>
To:	Ulf Hansson <ulf.hansson@...aro.org>
Cc:	Sergey Yanovich <ynvich@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Namjae Jeon <linkinjeon@...il.com>,
	linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org
Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts

Hi,

On Wed, Mar 27 2013, Ulf Hansson wrote:
> I noticed you merged this. I thought the idea was to use the rootwait
> or rootdelay?

That's necessary before the patch, but it would be better if we didn't
have to pass rootwait, all else being equal.

> Moreover, this patch will have bad impact on booting the kernel, since
> every host device that has scheduled a detect work from it's probe
> function will also wait for it to finish. Even if it is the boot
> device of not. If this is needed, I would prefer that a host cap is
> used.

I see, you're worried about a performance regression where every boot
takes longer than it used to while MMC quiesces.  That's fair.  Do you
think you could tell me how much delay this adds to a boot for you, so
that we can consider whether the usability improvement is worth it?

If the delay's significant, I agree with you and will revert this patch.

Thanks,

- Chris.
-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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