From: Ralph Corderoy <ralph@inputplus.co.uk>
To: coff@tuhs.org
Subject: [COFF] Re: Porting the SysIII kernel: boot, config & device drivers
Date: Mon, 02 Jan 2023 09:37:18 +0000 [thread overview]
Message-ID: <20230102093718.1102D220FA@orac.inputplus.co.uk> (raw)
In-Reply-To: <20230101212609.yjg2poiggil7pwat@illithid>
Hi Branden,
> Paul Ruizendaal wrote:
> > That was my immediate pain point in doing the D1 SoC port.
> > Unfortunately, the manufacturer only released the DRAM init code as
> > compiler ‘-S’ output and the 1,400 page datasheet does not discuss
> > its registers. Maybe this is a-typical, as I heard in the above
> > keynote that NXP provides 8,000 page datasheets with their SoC’s.
...
> I don't think it's atypical. I was pretty annoyed trying to use the
> data sheet to program a simple timer chip on the ODROID-C2
...
> OS nerds don't generally handle procurement themselves. Instead,
> purchasing managers do, and those people don't have to face the pain.
...
> Data sheets are only as good as they need to be to move the product,
> which means they don't need to be good at all, since the people who
> pay for them look only at the advertised feature list and the price.
I think it comes down to the background of the chip designer. I've
always found NXP very good: their documentation of a chip is extensive;
it doesn't rely on referring to external source code; and they're
responsive when I've found the occasional error, both confirming the
correction and committing to its future publication.
On the other hand, TI left a bad taste. The documentation isn't good
and they rely on a forum to mop up all the problems but it's pot luck
which staffer answers and perennial problems can easily be found by a
forum search, never with a satisfactory answer.
My guess is Allwinner, maker of Paul's D1 SoC, has a language barrier
and a very fast-moving market to dissuade them from putting too much
effort into documentation. Many simpler chips from China, e.g. a JPEG
encoder, come with a couple of pages listing features and some C written
by a chip designer or copied from a rival.
In my experience, chip selection is done by technical people, not
procurement. It's too complex a task, even just choosing from those of
one supplier like NXP, as there is often a compromise to make which
affects the rest of the board design. That's where FPGAs have an
allure, but unfortunately not in low-power designs.
--
Cheers, Ralph.
prev parent reply other threads:[~2023-01-02 9:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <335F89A9-30C2-41A2-8E84-C2D761746634@planet.nl>
[not found] ` <CAEoi9W4Np=Z80NdO60x4rEPY6qKaRKYq81aCZxLXX2LAD-9iCA@mail.gmail.com>
[not found] ` <CAC20D2O-fUbrCuvvzEj2Z4b2kV+J6TApYdBeMcWvPEADN-nL7w@mail.gmail.com>
[not found] ` <CAEoi9W4_ZwOst9yo2GiM4qO4EwapEFia9X7kDZjwQUuhxaEVVw@mail.gmail.com>
[not found] ` <CAC20D2NpQdY+oRj-qK45=LR6GuLR3w7ZVmu9SWBd4s6v_Mvepw@mail.gmail.com>
[not found] ` <alpine.BSF.2.21.9999.2301011017150.95173@aneurin.horsfall.org>
[not found] ` <CAKzdPgzcPVdm_x+WxG7VpssNY7fbr-c2S1ax4S9UOgPPDapOrQ@mail.gmail.com>
[not found] ` <CAKr6gn1b=JoNm-9a3iPrHr4QeOzLGFD=Zy6E47YXi6fX4ZGoaA@mail.gmail.com>
[not found] ` <20230101014054.GD5825@mcvoy.com>
2023-01-01 17:21 ` [COFF] Re: [TUHS] " Adam Thornton
2023-01-01 17:33 ` Lars Brinkhoff
[not found] ` <Y7C50dGWZ6yFDX74@mit.edu>
[not found] ` <DBC89F53-9A0A-4B34-A627-A9CFF5013EC3@planet.nl>
[not found] ` <20230101212609.yjg2poiggil7pwat@illithid>
2023-01-02 9:37 ` Ralph Corderoy [this message]
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