linux-kernel - Re: [PATCH 1/2] nvmem: sunxi-sid: add support for H3 and A64's SID controller

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Date:   Fri, 27 Jan 2017 10:41:33 +0100
From:   Maxime Ripard <maxime.ripard@...e-electrons.com>
To:     Icenowy Zheng <icenowy@...c.xyz>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Rob Herring <robh+dt@...nel.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...glegroups.com,
        devicetree@...r.kernel.org, Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH 1/2] nvmem: sunxi-sid: add support for H3 and A64's SID
 controller

On Fri, Jan 27, 2017 at 05:26:59PM +0800, Icenowy Zheng wrote:
> > > +Example for sun8i-h3: 
> > > + sid@...14000 { 
> > > + compatible = "allwinner,sun8i-h3-sid"; 
> > > + /* 
> > > + * The length of SID on H3 is 0x100 bytes, add the value offset 
> > > + * 0x200, so the total length should be 0x300. 
> > > + */ 
> > > + reg = <0x01c14000 0x300>; 
> >
> > No, it should be the size of the memory region used and documented for 
> > that device, ie 1kB (0x400) in the H3 case, just like any other reg 
> > property. 
> 
> So bind the SID size with compatible?

If needed, yes.

> > > - randomness = kzalloc(sizeof(u8) * (size), GFP_KERNEL); 
> > > + randomness_size = max(size, SUNXI_SID_MAX_RANDOMNESS_SIZE); 
> > > + randomness = kzalloc(sizeof(u8) * (randomness_size), GFP_KERNEL); 
> >
> > Why is that change needed? 
> 
> On my H3/H2+ only 2 words after the first 4 words is not zero.
> 
> I don't feel like add so many 0s to randomness.

As far as I know, filling the entropy pool with zeros does no harm, it
just doesn't do anything either.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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