[OLPC-devel] Re: [One Laptop Per Child] #72: LinuxBIOS needs to detect the DCON and communicate that information to the kernel

[Zarro Boogs per Child]

#72: LinuxBIOS needs to detect the DCON and communicate that information to the
kernel
--------------------------+-------------------------------------------------
 Reporter:  JordanCrouse  |        Owner:  JordanCrouse
     Type:  enhancement   |       Status:  new         
 Priority:  major         |    Milestone:              
Component:  linuxbios     |   Resolution:              
 Keywords:                |  
--------------------------+-------------------------------------------------
Old description:

> LinuxBIOS should detect and enable the DCON by writing a 0x69 to register
> 0x01 (DCON SMBUS slave address = 0x0D).  If the write fails, then it
> should be assumed the DCON doesn't exist.
>
> The BIOS should set a bit in the CMOS if the DCON exists.  The ROM kernel
> will use that bit to determine what default mode to use.  The main kernel
> may also use the bit, though it is expected that the main kernel will
> take control of the dcon directly via SMBUS.
>
> This enhancement has three parts:
>
>  * smbus_write_byte() support for the CS5536.  The SMBUS parts in
> LinuxBIOS need to be straightened out.  SMBus usage outside of the romcc
> code has fallen into disuse (rminich).
>  * Add the dcon detection code to the OLPC mainboard code and write the
> CMOS bit accordingly.
> (JordanCrouse)
>  * Grok the CMOS bit in the kernel and setup the video driver
> accordingly. (JordanCrouse)

New description:

 LinuxBIOS should detect and enable the DCON by writing a 0x69 to register
 0x01 (DCON SMBUS slave address = 0x0D).  If the write fails, then it
 should be assumed the DCON doesn't exist.

 The BIOS should set a bit in the CMOS if the DCON exists.  The ROM kernel
 will use that bit to determine what default mode to use.  The main kernel
 may also use the bit, though it is expected that the main kernel will take
 control of the dcon directly via SMBUS.

 This enhancement has three parts:

  * smbus_write_byte() support for the CS5536.  The SMBUS parts in
 LinuxBIOS need to be straightened out.  SMBus usage outside of the romcc
 code has fallen into disuse (rminich).
  * Add the dcon detection code to the OLPC mainboard code and write the
 CMOS bit accordingly. (JordanCrouse)
  * Grok the CMOS bit in the kernel and setup the video driver accordingly.
 (JordanCrouse)

-- 
Ticket URL: <http://dev.laptop.org/ticket/72#comment:1>
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