Re: [PATCH v3 04/11] thermal: armada: Rationalize register accesses

[Baruch Siach <baruch@tkos.co.il>]

Hi Miquèl,

On Sun, Dec 17, 2017 at 12:18:38AM +0200, Baruch Siach wrote:
> On Thu, Dec 14, 2017 at 11:30:04AM +0100, Miquel Raynal wrote:
> > Bindings were incomplete for a long time by only exposing one of the two
> > available control registers. To ease the migration to the full bindings
> > (already in use for the Armada 375 SoC), rename the pointers for
> > clarification. This way, it will only be needed to add another pointer
> > to access the other control register when the time comes.
> > 
> > This avoids dangerous situations where the offset 0 of the control
> > area can be either one register or the other depending on the bindings
> > used. After this change, device trees of other SoCs could be migrated to
> > the "full" bindings if they may benefit from features from the
> > unaccessible register, without any change in the driver.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
> > ---
> 
> [...]
> 
> > +	/*
> > +	 * Legacy DT bindings only described "control1" register (also referred
> > +	 * as "control MSB" on old documentation). New bindings cover
> > +	 * "control0/control LSB" and "control1/control MSB" registers within
> > +	 * the same resource, which is then of size 8 instead of 4.
> > +	 */
> > +	if ((res->end - res->start) == LEGACY_CONTROL_MEM_LEN) {
> > +		/* ->control0 unavailable in this configuration */
> > +		priv->control1 = control + LEGACY_CONTROL1_OFFSET;
> > +	} else {
> > +		priv->control0 = control + CONTROL0_OFFSET;
> > +		priv->control1 = control + CONTROL1_OFFSET;
> > +	}
> 
> I think we need to add a check here that the control registers area size 
> matches the expected value given the compatible string. In case of mismatch 
> probe should fail.

One more thing. You should probably use resource_size() instead of open coding 
it. resource_size() does "res->end - res->start + 1". Are you sure your code 
is correct?

> >  	priv->data = (struct armada_thermal_data *)match->data;
> >  	priv->data->init_sensor(pdev, priv);

baruch

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