Nokia n810 LCD (MIPID/blizzard) on 2.6.38

Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Michael Buesch]

The n810 LCD does not work on the 2.6.38(-rc6) kernel
due to changes in the OMAP GPIO-hwmod code.

The hwmod code performs a soft-reset on the GPIO
module. The first GPIO module carries the MIPID
"nreset" line, which is toggled due to the hwmod soft reset.
This resets Blizzard and breaks it, because
it assumes the LCD was left in the state that the
bootloader initialized it to:

	if (!(blizzard_read_reg(BLIZZARD_PLL_DIV) & 0x80)) {
		dev_err(fbdev->dev,
			  "controller not initialized by the bootloader\n");
		r = -ENODEV;
		goto err3;
	}

My temporary workaround to this issue is to disable
soft reset for the first GPIO module:

	static struct omap_hwmod omap2420_gpio1_hwmod = {
		.name           = "gpio1",
		.flags          = HWMOD_INIT_NO_RESET, /* Workaround: Don't reset the n810 MIPID */

I'm wondering if a better fix suitable for the mainline
kernel inclusion could be found.
Any ideas?

-- 
Greetings, Michael.

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Felipe Balbi]

On Mon, Feb 28, 2011 at 09:45:43PM +0100, Michael Buesch wrote:
> The n810 LCD does not work on the 2.6.38(-rc6) kernel
> due to changes in the OMAP GPIO-hwmod code.
> 
> The hwmod code performs a soft-reset on the GPIO
> module. The first GPIO module carries the MIPID
> "nreset" line, which is toggled due to the hwmod soft reset.
> This resets Blizzard and breaks it, because
> it assumes the LCD was left in the state that the
> bootloader initialized it to:

so that's the bug which needs to be fixed. Unfortunately I don't have
any documentation available anymore. Maybe someone from Nokia would fix
that ?

> I'm wondering if a better fix suitable for the mainline
> kernel inclusion could be found.
> Any ideas?

Don't depend on the bootloader :-)

-- 
balbi

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Michael Büsch]

On Tue, 2011-03-01 at 11:20 +0200, Felipe Balbi wrote: 
> On Mon, Feb 28, 2011 at 09:45:43PM +0100, Michael Buesch wrote:
> > The n810 LCD does not work on the 2.6.38(-rc6) kernel
> > due to changes in the OMAP GPIO-hwmod code.
> > 
> > The hwmod code performs a soft-reset on the GPIO
> > module. The first GPIO module carries the MIPID
> > "nreset" line, which is toggled due to the hwmod soft reset.
> > This resets Blizzard and breaks it, because
> > it assumes the LCD was left in the state that the
> > bootloader initialized it to:
> 
> so that's the bug which needs to be fixed. Unfortunately I don't have
> any documentation available anymore. Maybe someone from Nokia would fix
> that ?
> 
> > I'm wondering if a better fix suitable for the mainline
> > kernel inclusion could be found.
> > Any ideas?
> 
> Don't depend on the bootloader :-)

Yeah that's the obvious fix, of course. However, it requires
deep knowledge of the device and/or hardware documentation. Both
of which I don't have.
The driver also doesn't seem to have a maintainer.

If someone can get me documentation, I'm willing to implement
the required bits to remove the bootloader dependency.

-- 
Greetings Michael.

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Felipe Balbi]

On Tue, Mar 01, 2011 at 03:23:15PM +0100, Michael Büsch wrote:
> On Tue, 2011-03-01 at 11:20 +0200, Felipe Balbi wrote: 
> > On Mon, Feb 28, 2011 at 09:45:43PM +0100, Michael Buesch wrote:
> > > The n810 LCD does not work on the 2.6.38(-rc6) kernel
> > > due to changes in the OMAP GPIO-hwmod code.
> > > 
> > > The hwmod code performs a soft-reset on the GPIO
> > > module. The first GPIO module carries the MIPID
> > > "nreset" line, which is toggled due to the hwmod soft reset.
> > > This resets Blizzard and breaks it, because
> > > it assumes the LCD was left in the state that the
> > > bootloader initialized it to:
> > 
> > so that's the bug which needs to be fixed. Unfortunately I don't have
> > any documentation available anymore. Maybe someone from Nokia would fix
> > that ?
> > 
> > > I'm wondering if a better fix suitable for the mainline
> > > kernel inclusion could be found.
> > > Any ideas?
> > 
> > Don't depend on the bootloader :-)
> 
> Yeah that's the obvious fix, of course. However, it requires
> deep knowledge of the device and/or hardware documentation. Both
> of which I don't have.
> The driver also doesn't seem to have a maintainer.
> 
> If someone can get me documentation, I'm willing to implement
> the required bits to remove the bootloader dependency.

Someone from Nokia might be able to help. Kai ??

-- 
balbi
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Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Varadarajan, Charulatha]

Hi,

On Mon, Feb 28, 2011 at 15:45, Michael Buesch <mb@bu3sch.de> wrote:
> The n810 LCD does not work on the 2.6.38(-rc6) kernel
> due to changes in the OMAP GPIO-hwmod code.
>
> The hwmod code performs a soft-reset on the GPIO
> module. The first GPIO module carries the MIPID
> "nreset" line, which is toggled due to the hwmod soft reset.
> This resets Blizzard and breaks it, because
> it assumes the LCD was left in the state that the
> bootloader initialized it to:

It is the design of hwmod framework that all the omap devices
should be reset independent of bootloader settings. The
corresponding board file/ the driver should take care of init settings
of the device based on the requirement. Avoid dependency on
bootloader.

>
>        if (!(blizzard_read_reg(BLIZZARD_PLL_DIV) & 0x80)) {
>                dev_err(fbdev->dev,
>                          "controller not initialized by the bootloader\n");
>                r = -ENODEV;
>                goto err3;
>        }
>
> My temporary workaround to this issue is to disable
> soft reset for the first GPIO module:
>
>        static struct omap_hwmod omap2420_gpio1_hwmod = {
>                .name           = "gpio1",
>                .flags          = HWMOD_INIT_NO_RESET, /* Workaround: Don't reset the n810 MIPID */

NACK.

As the problem is specific to the board settings, this shall be handled
in the board file itself.

>
> I'm wondering if a better fix suitable for the mainline
> kernel inclusion could be found.
> Any ideas?

Re-initialize the  "nreset" line of the Blizzard in the
corresponding board file.

- V Charulatha

>
> --
> Greetings, Michael.
>
>
>
>
>
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Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Michael Büsch]

On Tue, 2011-03-01 at 11:23 -0500, Varadarajan, Charulatha wrote: 
> > My temporary workaround to this issue is to disable
> > soft reset for the first GPIO module:
> >
> >        static struct omap_hwmod omap2420_gpio1_hwmod = {
> >                .name           = "gpio1",
> >                .flags          = HWMOD_INIT_NO_RESET, /* Workaround: Don't reset the n810 MIPID */
> 
> NACK.
> 
> As the problem is specific to the board settings, this shall be handled
> in the board file itself.

Yeah, sure. But how can I handle this in the board file? Is
there a hwmod API for this?

> > I'm wondering if a better fix suitable for the mainline
> > kernel inclusion could be found.
> > Any ideas?
> 
> Re-initialize the  "nreset" line of the Blizzard in the
> corresponding board file.

That is not sufficient. The blizzard chip has to be reinitialized
completely.
Code for that doesn't exist in the current driver. It currently depends
on the bootloader doing the lowlevel init. As long as I don't have
documentation for that chip, I'm stuck with that.

-- 
Greetings Michael.

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Varadarajan, Charulatha]

On Tue, Mar 1, 2011 at 21:59, Michael Büsch <mb@bu3sch.de> wrote:
> On Tue, 2011-03-01 at 11:23 -0500, Varadarajan, Charulatha wrote:
>> > My temporary workaround to this issue is to disable
>> > soft reset for the first GPIO module:
>> >
>> >        static struct omap_hwmod omap2420_gpio1_hwmod = {
>> >                .name           = "gpio1",
>> >                .flags          = HWMOD_INIT_NO_RESET, /* Workaround: Don't reset the n810 MIPID */
>>
>> NACK.
>>
>> As the problem is specific to the board settings, this shall be handled
>> in the board file itself.
>
> Yeah, sure. But how can I handle this in the board file? Is
> there a hwmod API for this?
>
>> > I'm wondering if a better fix suitable for the mainline
>> > kernel inclusion could be found.
>> > Any ideas?
>>
>> Re-initialize the  "nreset" line of the Blizzard in the
>> corresponding board file.
>
> That is not sufficient. The blizzard chip has to be reinitialized
> completely.

Yes. I meant the same but did not mention it clearly :-(

> Code for that doesn't exist in the current driver. It currently depends
> on the bootloader doing the lowlevel init. As long as I don't have
> documentation for that chip, I'm stuck with that.

How about the following driver?
drivers/video/omap/blizzard.c

I guess this is the same Blizzard  LCD driver.

You may also be interested in the following which I came across while
searching for Blizzard LCD.

https://dev.openwrt.org/browser/trunk/target/linux/omap24xx/patches-2.6.36/300-nokia-board.patch?rev=23082

-V Charulatha

>
> --
> Greetings Michael.
>
>
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Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Tony Lindgren]

* Michael Buesch <mb@bu3sch.de> [110228 12:43]:
> 
> The hwmod code performs a soft-reset on the GPIO
> module. The first GPIO module carries the MIPID
> "nreset" line, which is toggled due to the hwmod soft reset.
> This resets Blizzard and breaks it, because
> it assumes the LCD was left in the state that the
> bootloader initialized it to:

The long term solution is to allow passing options to the
hwmod framework to not reset pins from both board-*.c
files and from cmdline.

For this case it would be nice to pass info from the board-*.c
file to hwmod so it knows to skip reset only for this GPIO.

For booting Linux from other OS, something like
hwmod.reset_disable=all is needed to keep the LCD on.

Regrads,

Tony

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Paul Walmsley]

Greetings Michael,

On Mon, 28 Feb 2011, Michael Buesch wrote:

> The n810 LCD does not work on the 2.6.38(-rc6) kernel
> due to changes in the OMAP GPIO-hwmod code.
> 
> The hwmod code performs a soft-reset on the GPIO
> module. The first GPIO module carries the MIPID
> "nreset" line, which is toggled due to the hwmod soft reset.
> This resets Blizzard and breaks it, because
> it assumes the LCD was left in the state that the
> bootloader initialized it to:

...

> My temporary workaround to this issue is to disable
> soft reset for the first GPIO module:

...

> I'm wondering if a better fix suitable for the mainline
> kernel inclusion could be found.
> Any ideas?

Perhaps this patch will do:

   http://marc.info/?l=linux-omap&m=129971920806386&w=2

Afterwards, it should be possible to look up the GPIO1 hwmod in 
mach-omap2/board-n8x0.c after the call to 
omap2_init_common_infrastructure(), and then to call 
omap_hwmod_no_setup_reset() on it.  Perhaps you might wish to try it?

...

Thanks for maintaining your N810 pages, they have proven quite useful over 
the years,

MfG,

- Paul

Re: Nokia n810 LCD (MIPID/blizzard) on 2.6.38

[Michael Büsch]

On Wed, 2011-03-09 at 18:18 -0700, Paul Walmsley wrote: 
> Perhaps this patch will do:
> 
>    http://marc.info/?l=linux-omap&m=129971920806386&w=2
> 
> Afterwards, it should be possible to look up the GPIO1 hwmod in 
> mach-omap2/board-n8x0.c after the call to 
> omap2_init_common_infrastructure(), and then to call 
> omap_hwmod_no_setup_reset() on it.  Perhaps you might wish to try it?

Yep, this looks like the short-term fix I was looking for.

We're still working on a possible long-term fix by fixing up
the blizzard driver, but that will eventually take some time, if
we finally get it sorted out...

-- 
Greetings Michael.