[9fans] Adjust Thinkpad Screen Brightness

[9fans] Adjust Thinkpad Screen Brightness

[zxcdewqa8]

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Hi

Is there anyway to adjust my laptop's (T440P) screen brightness?

Thanks!
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Re: [9fans] Adjust Thinkpad Screen Brightness

[ori]

Quoth zxcdewqa8@gmail.com:
> Hi
> 
> Is there anyway to adjust my laptop's (T440P) screen brightness?
> 
> Thanks!

not nicely integrated. Depending on your card, something like
this may work:

        #!/bin/rc
        # SBLC_PWM_CTL2: bytes 15:0, range 0 (off) to v>>16 (full)
        
        if(! ~ $#* 1){
                echo usage: $0 factor
                exit 'usage'
        }
        echo -n type igfx > /dev/vgactl
        v=`{seg -Lr igfxmmio 0x400000 0xc8254}
        if(~ $#v 0)
                exit 'no such named segment'
        v=`{echo 'v='$v'; v & ~0xffff | ((v>>16) / '$1')' | pc -n}
        if(! ~ $#v 1)
                exit 'invalid factor'
        sleep 0.1
        seg -Lw igfxmmio 0x400000 0xc8254 $v

You'll have to figure out where the backlight PWM register is
on your model of video card if this doesn't just work out of
the box.


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Re: [9fans] Adjust Thinkpad Screen Brightness

[Anthony Martin]

ori@eigenstate.org once said:
> not nicely integrated. Depending on your card, something like
> this may work:
>
> [...]
>
> You'll have to figure out where the backlight PWM register is
> on your model of video card if this doesn't just work out of
> the box.

Konstantinn wrote a version of your script with predetermined
register addresses for a bunch of cards:

https://shithub.us/qwx/rc/98421abf7681f7ae8d49c4e4e82ffbdc6b215ef6/bin/br/raw

Cheers,
  Anthony

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Re: [9fans] Adjust Thinkpad Screen Brightness

[zxcdewqa8]

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Using Ori's script works on my Thinkpad T440P, but one small change (
0x48254).

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Re: [9fans] Adjust Thinkpad Screen Brightness

[plan6]

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Hello :) None of them seems to work on my thinkpad x230 with coreboot. All I get is a black screen, whatever the number I enter in each script (1 to 8 for Ori's, percentage for Konstantinn). Any help would be really appreciated :)
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Re: [9fans] Adjust Thinkpad Screen Brightness

[mkf9]

Hi.
likely x230's coreboot mises something, as brightness buttons doesn't 
work either on 9front, while they do work with stock bios.

plan6@room3420.net wrote:
> Hello :) None of them seems to work on my thinkpad x230 with coreboot. All I get is a black screen, whatever the number I enter in each script (1 to 8 for Ori's, percentage for Konstantinn). Any help would be really appreciated :)

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Re: [9fans] Adjust Thinkpad Screen Brightness

[unobe]

Quoth mkf9 <mkf9@riseup.net>:
> likely x230's coreboot mises something, as brightness buttons doesn't 
> work either on 9front, while they do work with stock bios.

Confirmed on my x230 as well--the scripts do not work.

But for me, if I press the 'fn' key and then the brightness buttons,
they do indeed work.  I reviewed the data sheet and the scripts should
work, but does not.


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Re: [9fans] Adjust Thinkpad Screen Brightness

[Anthony Martin]

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unobe@cpan.org once said:
> I reviewed the data sheet and the scripts should
> work, but does not.

The above scripts can work for some Intel cards
but probably not for all of them.

I wrote a program fifteen years ago to adjust the
brightness on an Intel MacBook from Linux. There
was a bit of experimentation involved to determine
register values that wouldn't cause problems. I've
attached it below.

Notice how I had to use a mask of 0xfffe instead
of 0xffff to keep the least significant bit zero
and how I had to be strict about maintaining the
maximum backlight level field when reading and
writing the register. I remember working through a
lot of blank and flickering screens before
arriving at something that worked.

I'm not near a machine with an Intel card at the
moment so I can't give you something that works on
Plan 9 but reading this old code may give you some
hints.

Cheers,
  Anthony

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#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <pci/pci.h>

typedef unsigned short	ushort;
typedef unsigned int	uint;

// A barebones representation of a PCI device.
typedef struct Pcidev Pcidev;
struct Pcidev {
	ushort     vid;  // PCI vendor ID.
	ushort     did;  // PCI device ID.
	pciaddr_t  bar;  // Physical address of the first BAR.
	size_t     size; // Size of the first BAR.
	char*      addr; // Mapped virtual address of the first BAR.
};

// Macros to read and write 32-bit PCI memory registers.
#define reg32r(p, r)    (*(uint*)((p)->addr+(r)))
#define reg32w(p, r, v)	(*(uint*)((p)->addr+(r)) = (v))

enum {
	// The PCI vendor and device ID for the Intel 945GM graphics chipset.
	Intel  = 0x8086,
	I945GM = 0x27a2,

	// The backlight PWM control register offset.
	Bctl = 0x061254,

	// The backlight duty cycle mask. The LSB must be zero.
	Bmask = 0xfffe,

	// The empirically observed range for valid brightness levels.
	Boff = 0x0000,
	Bmin = 0x003e,
	Bmax = 0x0128,

	// Without an explicit value, we increase or decrease by this
	// quantum so that there are only ten brightness levels.
	Bquant = (Bmax-Bmin)/(10-1),
};

// We don't expose the hardware-centric brightness levels to the user
// but instead shift the range down so it starts at one. These macros
// convert to and fro.
#define B(u)	(((u) == 0) ? Boff : (u)+Bmin-1)
#define U(b)	(((b) == Boff) ? 0 : (b)-Bmin+1)

// The set of operations that can be performed on the backlight.
enum {
	Onop = 1<<0,
	Oset = 1<<1,
	Oadd = 1<<2|Oset,
	Osub = 1<<3|Oset,
};

// The high sixteen bits of the opcode are only used for operations
// that require a numeric argument. These macros ease extraction.
#define OP(o)    ((o)&0xFFFF)
#define OPVAL(v) (((v)&0xFFFF)<<16)

char*	argv0;

void	fatal(char*, ...);
int	pcimatch(Pcidev*, int, int);

int
main(int argc, char *argv[])
{
	int o, fd, max, cur, new;
	char *s, *end;
	Pcidev p;

	// Determine which operation to perform.
	argv0 = argv[0];
	switch(argc){
	default:
		fprintf(stderr, "usage: %s [+-][val]\n", argv0);
		exit(EXIT_FAILURE);
	case 1:
		o = Onop;
		break;
	case 2:
		s = argv[1];
		if(*s == '+' || *s == '-'){
			o = (*s == '+') ? Oadd : Osub;
			s++;
		} else
			o = Oset;
		if(o != Oset && *s == '\0')
			o |= OPVAL(Bquant);
		else {
			o |= OPVAL(strtol(s, &end, 10));
			if(errno != 0 || end == s)
				fatal("invalid number");
		}
		break;
	}

	// Map the GPU device into memory so we can access the backlight register.
	if(pcimatch(&p, Intel, I945GM) < 0)
		fatal("pcimatch failed");
	fd = open("/dev/mem", O_RDWR);
	if(fd < 0)
		fatal("open /dev/mem failed");
	p.addr = mmap(NULL, p.size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, p.bar);
	if(p.addr == MAP_FAILED)
		fatal("map failed");
	close(fd);
	max = reg32r(&p, Bctl) >> 16;
	if(max != Bmax)
		fatal("invalid maximum: have %d want %d", max, Bmax);

	// Load the current brightness level and change it, if applicable.
	cur = reg32r(&p, Bctl) & Bmask;
	new = 0;
	switch(OP(o)){
	case Oset:
		new = B(o>>16);
		break;
	case Oadd:
		new = (cur == Boff) ? Bmin : cur + (o>>16);
		break;
	case Osub:
		new = (cur == Bmin) ? Boff : cur - (o>>16);
		break;
	}
	if(o & Oset){
		if(new < 0)
			new = Boff;
		if(new > 0){
			if(new < Bmin)
				new = Bmin;
			if(new > Bmax)
				new = Bmax;
		}
		reg32w(&p, Bctl, (new&Bmask)|(Bmax<<16));
		cur = reg32r(&p, Bctl) & Bmask;
	}

	// Unmap the device and print the current backlight level.
	munmap(p.addr, p.size);
	printf("%d/%d\n", U(cur), U(Bmax));
	return 0;
}

#define nil ((void*)0)

static struct pci_access* pciacc;
static struct pci_dev*    pcilist;

int
pcimatch(Pcidev* p, int vid, int did)
{
	static int pcicfgmode = -1;
	struct pci_access *a;
	struct pci_dev *prev;
	int req;

	if(pcicfgmode == -1){
		a = pci_alloc();
		if(a == nil)
			fatal("pci_alloc failed");
		pci_init(a);
		pci_scan_bus(a);
		pcilist = a->devices;
		pciacc = a;
		pcicfgmode = 0;
	}

	prev = pcilist;
	req = PCI_FILL_IDENT | PCI_FILL_BASES;
	pci_fill_info(prev, req);
	while(prev != nil){
		if((vid == 0 || prev->vendor_id == vid)
		&& (did == 0 || prev->device_id == did))
			break;
		prev = prev->next;
	}
	if(prev == nil)
		return -1;
	p->vid = prev->vendor_id;
	p->did = prev->device_id;

	p->bar = prev->base_addr[0] & PCI_ADDR_MEM_MASK;
	p->size = prev->size[0];
	pci_cleanup(pciacc);
	return 0;
}

void
fatal(char *fmt, ...)
{
	char buf[4096];
	va_list arg;
	int n;

	n = snprintf(buf, sizeof buf, "%s: ", argv0);
	va_start(arg, fmt);
	n += vsnprintf(buf+n, sizeof buf-n, fmt, arg);
	va_end(arg);
	if(errno)
		n += snprintf(buf+n, sizeof buf-n, ": %s", strerror(errno));
	n += snprintf(buf+n, sizeof buf-n, "\n");
	write(2, buf, n);
	exit(EXIT_FAILURE);
}

Re: [9fans] Adjust Thinkpad Screen Brightness

[plan6]

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Well, I guess mkf9 is right.  Coreboot misses something. I hope I won't have to reinstall the original BIOS. I feel like a download progress bar on Windows. Stuck at 99%.
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Re: [9fans] Adjust Thinkpad Screen Brightness

[unobe]

Quoth Anthony Martin <ality@pbrane.org>:
> unobe@cpan.org once said:
> > I reviewed the data sheet and the scripts should
> > work, but does not.
> 
> The above scripts can work for some Intel cards
> but probably not for all of them.

Thank you, Anthony.  That script helped me review the volumes again
and find out where the 'br' script is wrong.  It was just reading from
the wrong register for Ivy Bridge.  Here's the patch for qwx/rc's
branch, and it works like a charm now on my x230t.

From: Romano <unobe@cpan.org>
Date: Thu, 08 Jun 2023 07:49:37 +0000
Subject: [PATCH] Ivy Bridge uses South Display for reading brightness levels, per Vol. 3 Part 3 and 4 of Programmer's Reference

---
diff a9e9e008d4574c55fd9452de2cfc2cf9d964e7e5 d52fd7d1b16ce1e4f06607bfcec6859285077536
--- a/bin/br
+++ b/bin/br
@@ -29,8 +29,8 @@
        # works on x220, not on w520
        did["8086/0126","r"] = "0xc8254";  did["8086/0126","w"] = "0x48254"
        # ivy bridge
-       did["8086/0152","r"] = "0x48254";  did["8086/0152","w"] = "0x48254"
-       did["8086/0166","r"] = "0x48254";  did["8086/0166","w"] = "0x48254"
+       did["8086/0152","r"] = "0xc8254";  did["8086/0152","w"] = "0x48254"
+       did["8086/0166","r"] = "0xc8254";  did["8086/0166","w"] = "0x48254"
        # haswell
        did["8086/0412","r"] = "0xc8254";  did["8086/0412","w"] = "0x48254"
        did["8086/041a","r"] = "0xc8254";  did["8086/041a","w"] = "0x48254"


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Re: [9fans] Adjust Thinkpad Screen Brightness

[unobe]

Note the patch is for both the Ivy Bridge listed devices, but mine
specifically is 8086/0166.  I'm curious if there's someone with 0152.

Quoth unobe@cpan.org:
> Quoth Anthony Martin <ality@pbrane.org>:
> > unobe@cpan.org once said:
> > > I reviewed the data sheet and the scripts should
> > > work, but does not.
> > 
> > The above scripts can work for some Intel cards
> > but probably not for all of them.
> 
> Thank you, Anthony.  That script helped me review the volumes again
> and find out where the 'br' script is wrong.  It was just reading from
> the wrong register for Ivy Bridge.  Here's the patch for qwx/rc's
> branch, and it works like a charm now on my x230t.
> 
> From: Romano <unobe@cpan.org>
> Date: Thu, 08 Jun 2023 07:49:37 +0000
> Subject: [PATCH] Ivy Bridge uses South Display for reading brightness levels, per Vol. 3 Part 3 and 4 of Programmer's Reference
> 
> ---
> diff a9e9e008d4574c55fd9452de2cfc2cf9d964e7e5 d52fd7d1b16ce1e4f06607bfcec6859285077536
> --- a/bin/br
> +++ b/bin/br
> @@ -29,8 +29,8 @@
>         # works on x220, not on w520
>         did["8086/0126","r"] = "0xc8254";  did["8086/0126","w"] = "0x48254"
>         # ivy bridge
> -       did["8086/0152","r"] = "0x48254";  did["8086/0152","w"] = "0x48254"
> -       did["8086/0166","r"] = "0x48254";  did["8086/0166","w"] = "0x48254"
> +       did["8086/0152","r"] = "0xc8254";  did["8086/0152","w"] = "0x48254"
> +       did["8086/0166","r"] = "0xc8254";  did["8086/0166","w"] = "0x48254"
>         # haswell
> did["8086/0412","r"] = "0xc8254";  did["8086/0412","w"] = "0x48254"
> did["8086/041a","r"] = "0xc8254";  did["8086/041a","w"] = "0x48254"
> 

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Re: [9fans] Adjust Thinkpad Screen Brightness

[plan6]

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Ô my ! It works. Thank you all. If you come to Marseille, France, any day, I owe you a beer :)
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Re: [9fans] Adjust Thinkpad Screen Brightness

[zxcdewqa8]

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Hi, 
A newbie question:  how do I automate this so it runs automatically after boot up?
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Re: [9fans] Adjust Thinkpad Screen Brightness

[unobe]

Perhaps look at 'man 8 cpurc'.

Quoth zxcdewqa8@gmail.com:
> Hi,
> A newbie question:  how do I automate this so it runs automatically after boot up?

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Re: [9fans] Adjust Thinkpad Screen Brightness

[ori]

Quoth zxcdewqa8@gmail.com:
> Hi, 
> A newbie question:  how do I automate this so it runs automatically after boot up?

man termrc
cat $home/lib/profile

either will work.


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