On Wednesday, November 18, 2015 at 05:38:02 PM, Aleksander Morgado wrote: > On Tue, Nov 10, 2015 at 5:15 PM, Marek Vasut <ma...@denx.de> wrote: > >> >> >>> > About the parity -- can we add some flag into the datagram to > >> >> >>> > indicate we want hardware to calculate the parity for that > >> >> >>> > particular datagram for us? And we'd also need to indicate what > >> >> >>> > type of parity. I dunno if this is worth the hassle. > >> >> >>> > >> >> >>> This is HW configuration property, it does not belong to > >> >> >>> datagram. Also for TX channels, parity could be two kinds: > >> >> >>> odd and even, for RX it is only on/off. > >> >> >> > >> >> >> There are datagrams which do contain parity and ones which do not > >> >> >> contain it, correct ? Thus, it's a property of that particular > >> >> >> datagram. > >> >> > >> >> All ARINC words have bit #31 as parity bit; whether it's used or not > >> >> depends on the setup as Andrey says below. > >> > > >> > Can bit 31 be ever used for DATA instead of parity ? Or is this just > >> > me not understanding the parlance of the specification, where "DATA" > >> > actually means "DATA with parity" ? > >> > >> Well, as far as I know bit 31 is always parity bit, never used for > >> actual data contents. Which is the spec section that got you confused? > >> Maybe I'm the one which didn't read it well? > > > > Sorry for being so late into the discussion. > > > > I got confused by hi-3585_v-rev-l.pdf page 7 right, CR4 lets you treat > > bit 32 as either data or parity. But I guess this is not the general > > case. > > > > So I wonder, does it make sense to treat the P bit as data always and do > > parity in software or not ? > > I don't have an strong opinion on this, truth be told. It really > depends on whether we can tell the HW "go compute the parity > yourself". If we can ask for that, maybe we should allow configuring > that in the API with some flag. But anyway, treating P as data (i.e. > software should set parity bit to whatever is needed) is the most > generic thing you could do for a start, that shouldn't be wrong.
OK, let's treat it as data. Since RC1 is out, I should start reworking the framework into more sensible shape and repost before I miss the opportunity. Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
