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examining n800 kernel
 

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dufkaf at seznam

Jan 16, 2007, 5:57 AM


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examining n800 kernel

Hi,

I've been looking at the n800 kernel source in bora repository to figure
out what n800 is like comparing to the n770. Here is a summary of some
things I found. As I don't have the device I may be wrong with something
that could be easily verified.

kernel is 2.6.18-omap1 - everybody probably knows that :-)

MMC/SD

4 bit data bus seems to be used only for SD cards, omap2 maximum speed
is now set to 48Mhz (was 24Mhz for omap1 reduced to 12Mhz for N770).
There are no high speed MMCmobile/plus (or high speed SD) patches
applied so I guess SD cards run at 24Mhz, MMC at 16Mhz. There are also
no patches for wider bus width (4 bit) for MMCmobile. SDHC cards are not
supported too. As there are patches floating on the net for all these
things (done mostly by Philip Langdale http://intr.overt.org/blog/)
future looks promising :-) Oh, BTW multiblock writes _are_ enabled in
this kernel.

Video

similar setup like N770 but hopefully improved (finally no memory
bicycle but proper bus?). The external videochips seems to be from epson
too, not 472 but 475 (or 4 in early prototypes?) called Blizzard and
Hailstorm. Difference seems to be bigger memory buffer (1280K) that
allows 24 bits in 800x480 instead of 16 on N770. See also
http://www.erd.epson.com/index.php?option=com_docman&task=cat_view&gid=68&Itemid=40
So the framebuffer is still external but handled by something different.
OMAP1 uses something called SOSSI, OMAP2 calls it RFBI (remote frame
buffer ...) Interesting is that omap framebuffer driver now contains
code for synchronization on vblank and preventing tearing effect. It is
both in omapfb/blizzard/rfbi code for n800 and also for
omapfb/hwa472/sossi code for n770! Lets hope some variant of this kernel
will go into some future n770 firmware. If not we can try to backport it
for mplayer. from the code it looks like the pin from 472 chip
signalling horizontal or vertical blank perion is indeed connected to
something and checked (?) inside sossi driver. The is still no support
for display rotation feature of the epson chip.

Both IVA and MBX are a bit of a mystery to me. Probably another ones to
the bag with jazzelle technology so it won't feel alone there unused :-)
http://focus.ti.com/general/docs/wtbu/wtbugencontent.tsp?templateId=6123&navigationId=12719&contentId=27458

USB

Seems to be 2.0, capable of high speed mode (480MBits), chip is TUSB6010
by TI. No usb host mode is compiled in the kernel. Usb host mode support
was also removed from initfs (usb booting) so this may look bad.

BT

Was already discussed, see the bt headsed thread - Bluecore4 CSR chip
capable of BT2.0, driver is called hci_h4p in drivers/bluetooth/hci_h4p
(not present in mainline kernel?).

WI-FI

seems to be same chip as in (newer) N770 devices (?), similar firmware
blobs (3825.arm, 3826.arm) probably newer versions. Hopefully the speed
will be better that those 500KB/s on N770 thanks to rest of the system.

Audio

Alsa compiled in, OMAP24xx EAC driver, mixer support, PCM should be
handled by DSP.

Feel free to correct or expand if something is wrong/missing.

Frantisek
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Subject User Time
examining n800 kernel dufkaf at seznam Jan 16, 2007, 5:57 AM
    Re: examining n800 kernel marcel at holtmann Jan 16, 2007, 6:16 AM
    Re: examining n800 kernel daniel.stone at nokia Jan 16, 2007, 10:57 AM
        Re: examining n800 kernel barbieri at gmail Jan 16, 2007, 7:23 PM
    Re: examining n800 kernel lbattraw at gmail Jan 16, 2007, 12:33 PM
    Re: examining n800 kernel dufkaf at seznam Jan 17, 2007, 12:26 AM
    Re: examining n800 kernel Kalle.Valo at nokia Jan 17, 2007, 1:13 AM
    RE: examining n800 kernel Jakub.Pavelek at nokia Jan 17, 2007, 1:17 AM

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