Re: [PATCH] radeonfb: Let hwmon driver probe the "monid" I2C bus

[Alexander Goomenyuk <emerg.reanimator@gmail.com>]

On Thu, 2011-01-13 at 14:44 +1000, Dave Airlie wrote:
> On Thu, Jan 13, 2011 at 2:11 PM, Paul Mundt <lethal@linux-sh.org> wrote:
> > On Tue, Jan 11, 2011 at 04:23:52PM +0100, Jean Delvare wrote:
> >> Some Radeon cards have an I2C-based thermal sensor chip connected to
> >> the "monid" I2C bus. Set the I2C probing class of this bus properly so
> >> that hwmon drivers can detect devices on it and bind to them.
> >>
> >> This closes kernel.org bug #26172.
> >>
> 
> The radeon BIOS actually contains a table to tell us what chip is on the bus,
> in the KMS driver we read this table and load the appropriate hwmon device,
> 
> There could possibly be other things on this bus than hw monitor devices.
> 
> Though radeonfb should be considered mostly dead.
> 
> Dave.

I have tried radeon KMS driver.
        modinfo output:
        filename:       /lib/modules/2.6.36-tuxonice-r3/kernel/drivers/gpu/drm/radeon/radeon.ko
        depends:
        drm,drm_kms_helper,ttm,fb,i2c-core,cfbfillrect,cfbimgblt,cfbcopyarea,i2c-algo-bit
        vermagic:       2.6.36-tuxonice-r3 SMP mod_unload 686 
        parm:           no_wb:Disable AGP writeback for scratch
        registers (int)
        parm:           modeset:Disable/Enable modesetting (int)
        parm:           dynclks:Disable/Enable dynamic clocks (int)
        parm:           r4xx_atom:Enable ATOMBIOS modesetting for R4xx
        (int)
        parm:           vramlimit:Restrict VRAM for testing (int)
        parm:           agpmode:AGP Mode (-1 = PCI) (int)
        parm:           gartsize:Size of PCIE/IGP gart to setup in
        megabytes (32,64, etc)
         (int)
        parm:           benchmark:Run benchmark (int)
        parm:           test:Run tests (int)
        parm:           connector_table:Force connector table (int)
        parm:           tv:TV enable (0 = disable) (int)
        parm:           new_pll:Select new PLL code (int)
        parm:           audio:Audio enable (0 = disable) (int)
        parm:           disp_priority:Display Priority (0 = auto, 1         normal, 2 = high) (int)
        parm:           hw_i2c:hw i2c engine enable (0 = disable) (int)
        
But it also need modifications in order to be used by lm63 hwmon driver.
1. MONID line is disable by combios_setup_i2c_bus() for RV380 because
of:
        case CHIP_RV350:
        case CHIP_RV380:
        case CHIP_RS400:
        case CHIP_RS480:
                switch (ddc_line) {
                case RADEON_GPIO_VGA_DDC:
                case RADEON_GPIO_DVI_DDC:
+                       i2c.hw_capable = true;
-                       i2c.hw_capable = false;
                        break;
                case RADEON_GPIO_MONID:
                     /* hw i2c on RADEON_GPIO_MONID doesn't seem to work
                      * reliably on some pre-r4xx hardware; not sure why
                      */
                        i2c.hw_capable = true;
                        break;

extracted from the sources.
It would be nice if there will be some driver parameter to control this
behavior. Or/and control it in kernel configuration menu.

2. MONID adapter is not registered as HWMON capable.
So I have added the following line into radeon_combios_i2c_init():

        } else if (rdev->family >= CHIP_R300) {
               i2c = combios_setup_i2c_bus(rdev, DDC_MONID, 0, 0);
               rdev->i2c_bus[3] = radeon_i2c_create(dev, &i2c, "MONID");
+              rdev->i2c_bus[3]->adapter.class = I2C_CLASS_HWMON;

Now I see GPU temperature using lm_sensors.

P.S. There is also strange side effect after reloading radeon driver
from X console: the screen switch off. So I have to switch between
virtual console and X. Is it an bug?