Hi Baruch,
On Tue, 19 Dec 2017 10:19:41 +0200
Baruch Siach <baruch@xxxxxxxxxx> wrote:
> Hi Miquèl,
>
> On Tue, Dec 19, 2017 at 09:08:14AM +0100, Miquel RAYNAL wrote:
> > On Tue, 19 Dec 2017 07:51:54 +0200
> > Baruch Siach <baruch@xxxxxxxxxx> wrote:
> > > On Tue, Dec 19, 2017 at 01:32:33AM +0100, Miquel RAYNAL wrote:
> > > > On Mon, 18 Dec 2017 22:35:42 +0200
> > > > Baruch Siach <baruch@xxxxxxxxxx> wrote:
> > > > > On Mon, Dec 18, 2017 at 03:36:35PM +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@xxxxxxxxxxxxxxxxxx> Reviewed-by: Gregory
> > > > > > CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> ---
> > > > >
> > > > > [...]
> > > > >
> > > > > > + /*
> > > > > > + * 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 (resource_size(res) == 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;
> > > > > > + }
> > > > >
> > > > > The needs_control0 field that you mentioned in the cover page
> > > > > is missing here.
> > > >
> > > > Yes, at this point nobody actually *needs* control0 so the
> > > > limitation is added with the patch that introduce ap806 support
> > > > as it is the first compatible that needs both control0 and
> > > > control1 to work correctly. Does this bother you?
> > >
> > > No. It is just that we agreed to have a verification here that the
> > > size of the control registers resource matches the binding. I
> > > thought that the needs_control0 field that you mention in the
> > > cover page is meant to implement that.
> >
> > That is absolutely right, but at this point in the series, the
> > supported compatible strings are
> > "marvell,armada[370|375|38x|xp]-thermal". All of them can use both
> > bindings so I don't see the point to have a needs_control0 field in
> > this patch. It is introduced in the next patch that adds support
> > for ap806 by only supporting the new bindings though.
>
> OK. Makes sense.
>
> > > necessary. It would just make sure that no one introduces a DT
> > > with the wrong resource size.
> >
> > Not sure I understand what exactly you wanna check, can you
> > give me an example?
>
> I wrote that before it occurred to me that we can use the control
> registers size the distinguish between the old binding and the new
> one.
>
> I still think it would be nice to add needs_control0=true to
> armada375_data, for consistency with the ap806 and cp110.
Oh that is right, I forgot about that. I will add it and move the
need_control0 boolean to this patch.
Thank you,
Miquèl
>
> baruch
>
--
Miquel Raynal, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
