Il Sat, Feb 28, 2004 at 06:54:08PM +0100, Jean Delvare ha scritto:
> According to Jon, it's required only for some old monitors. BTW, Jon,
> where did you get this information from?
XFree driver.
> Frankly, I don't see the point in handling these old monitors. At least,
> I wouldn't support them unless someone specifically asks for it and
> provides enough information for us to do the right thing.
Agreed, I'll talk to Benh about this issue.
> As for where the code should be, I still think it is *not* possible to
> put it in the chip driver. If I understand it correctly, before the
> special sequence is send on the bus, the EDID does *not* respond to any
> I2C address. This means that the ddcmon driver will *never* be called.
That's not correct. You can remove the code that touches SDA/SCL but you
need to activate i2c bus first:
OUTREG(reg, INREG(reg) & ~(VGA_DDC_DATA_OUTPUT | VGA_DDC_CLK_OUTPUT));
Btw, the voodoo code is the following:
radeon_gpio_setscl(chan, 1);
radeon_gpio_setsda(chan, 1);
/* Looks like a start */
radeon_gpio_setscl(chan, 1);
wait for radeon_gpio_getscl(chan); /* ack ? */
radeon_gpio_setsda(chan, 0);
radeon_gpio_setscl(chan, 0);
/* Stop ? */
radeon_gpio_setsda(chan, 1);
read EDID
radeon_gpio_setsda(chan, 0);
radeon_gpio_setscl(chan, 0);
/* Stop ? */
radeon_gpio_setscl(chan, 1);
wait for radeon_gpio_getscl(chan); /* ack ? */
radeon_gpio_setsda(chan, 1);
/* Start */
radeon_gpio_setsda(chan, 0);
radeon_gpio_setscl(chan, 0);
/* Stop again */
It seems pointeless to me, but it comes from XFree radeon driver. Can
you make any sense out of it?
> > Also, I don't think that is safe to attach a client to radeon DDC
> > busses (yet). During probe I fiddle directly with the adapter (without
> > any locking), if another client kicks in I fear that it will blow up.
> > radeonfb should register its own clients for probing EDID, it's in my
> > TODO list.
>
> I have been trying it :) And it worked correctly. Anyway, the radeonfb
> driver only probes the EDID at startup, right? So accessing it later
> sounds safe.
radeonfb can be build as a module, and we have a preemptible kernel... doh!
> Thanks Kronos for entering the thread. I hadn't even realized you were
> subscribed to the list.
I'm not, but Jon put me on CC.
Luca
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