From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [PATCH v4 2/3] dtc: Support character literals in cell lists Date: Tue, 20 Sep 2011 13:34:41 +1000 Message-ID: <20110920033441.GI29197@yookeroo.fritz.box> References: <1315595791-25793-1-git-send-email-robotboy@chromium.org> <1315595791-25793-3-git-send-email-robotboy@chromium.org> <20110912004437.GG9025@yookeroo.fritz.box> <20110919020034.GJ9025@yookeroo.fritz.box> <20110920005931.GB29197@yookeroo.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Anton Staaf Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Sep 19, 2011 at 07:54:09PM -0700, Anton Staaf wrote: > On Mon, Sep 19, 2011 at 5:59 PM, David Gibson > wrote: > > On Mon, Sep 19, 2011 at 09:45:34AM -0700, Anton Staaf wrote: > >> On Sun, Sep 18, 2011 at 7:00 PM, David Gibson > >> wrote: > >> > On Sat, Sep 17, 2011 at 11:49:21AM -0500, Jon Loeliger wrote: > >> >> > On Fri, Sep 09, 2011 at 12:16:30PM -0700, Anton Staaf wrote: > >> >> > > With this patch the following property assignment: > >> >> > > > >> >> > > =A0 =A0 property =3D <0x12345678 'a' '\r' 100>; > >> >> > > > >> >> > > is equivalent to: > >> >> > > > >> >> > > =A0 =A0 property =3D <0x12345678 0x00000061 0x0000000D 0x000000= 64> > >> >> > > > >> >> > > Signed-off-by: Anton Staaf > >> >> > > >> >> > Acked-by: David Gibson > >> >> > >> >> So, I *think* we want to wait until the question of size > >> >> is resolved some more, right? =A0Or, take this in any event > >> >> as "without a type indicator they are all 32-bit values"? > >> > > >> > No this patch is fine to take without changing the cell size > >> > semantics. =A0It's just that it becomes a lot more useful when we do= get > >> > those. > >> > >> Yup, I'm working on a size patch by the way. =A0Any comments on my > >> previous post about it would be helpful. =A0But in the mean time I'm > >> going ahead with a solution where the current cell size is stored in > >> the "struct data" type references are not allowed in cell lists of > >> size other than 32 bits. > > > > Ah, sorry, I meant to give comments on that earlier but got > > sidetracked. > > > > Storing the cell size in struct data doesn't really work - a single > > property could be assembled from several cell lists of different > > sizes. =A0By the time the reference substitution happens, they will have > > been all merged into a single struct data. > > > > I think prohibiting cell references anywhere but 32-bit cell lists is > > the right approach, but we need to work out a way to do the check > > during the parse phase. > = > Yes absolutely. My intent with storing the current cell size in the > data struct was to use that to do the parse time rejection of > references in all but 32-bit cell lists. That is the current cell > size would not be used past parsing, for exactly the reason you > mention. My thought was that every creation of a cell list would set > the current cell size to 32 or the value defined by /size/ and the > closing '>' would set it back to 0. The empty_data initializer would > set the current cell size to 0, even though it should never be used > outside of the <...> context. Then when a reference or literal are to > be appended to the current data struct we can check for the value 32 > if it's a reference, and otherwise use the current cell size to > validate (ensure it fits in the current cell size) and pad (add > leading zero's) the literal. Padding won't actually be required if > the literal parsing routine always returns a 64-bit value. Oh, I see. I guess that would work, but it's a really nasty misuse of a long-term data structure to store some short-term information. No, I'm pretty sure we can rearrange the grammer to handle this more cleanly. Maybe something like this: cellarrayprefix =3D DT_SIZE DT_LITERAL '<' | cellarrayprefix cellval | cellarrayprefix DT_REF | cellarrayprefix DT_LABEL The semantic type of cellarray prefix would need to contain both a struct data and a int for the cell size, which is a bit fiddly, but should be doable. The DT_REF case can check the cell size part of $1 and error if it's no 32-bit. -- = David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson