[Openchrome-users] [openChrome] #371: epia m10000 memory module detection limits resolution

[OpenChrome Trac]

#371: epia m10000 memory module detection limits resolution
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Reporter:  fpradines  |       Owner:  somebody                  
    Type:  defect     |      Status:  new                       
Priority:  minor      |   Component:  modesetting               
 Version:             |    Keywords:  dram speed bandwidth check
Blocking:             |   Blockedby:                            
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 Hi,

 I purchased some month ago a 28 inch lcd monitor. It's native resolution
 is 1920x1200 but the openchrome driver doesn't want to use it and gives
 only 1680x1050 as a maximum, talking about bandwidth (Xorg.0.log
 attached).
 Having a look at the code, the type of memory module appears to be what is
 chosen in the bios menu. On epia m10000, the menu contains 100Mhz, 133Mhz,
 by SPD. At best the mother board can handle pc2100 memory module. When
 chosing by SPD in the bios menu, all the openchrome driver gets is the
 last choice done between 100 and 133. It seems not so reliable.
 Searching a bit, it seems the correct way to find the type of memory
 module in the box is to load a kernel module (eeprom) and decode the dimm
 information the kernel got from data in the module(spd).
 decode_dimm.pl is working fine and giving the correct answer :
 http://www.lm-sensors.org/browser/lm-sensors/trunk/prog/eeprom/decode-
 dimms.pl?rev=3310
 But it seems a little bit complex to add to the driver.
 By curiosity, I tried to disconnect the bandwidth check based on memory
 speed. Normally it is only possible in debug mode, but with a few
 modifications (patch attached) it has been working perfectly for 6 months
 at 1920x1200 native resolution.

 Does it make sense to integrate these modifications and enable anybody to
 bypass the bandwidth check by config file ?
 Is there a danger somewhere for the hardware ?
 Should my box and my monitor have blown all the building ?
 Was that check already outdated 10 years ago ?

 Regards,

 Fran?ois Pradines

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Ticket URL: <http://www.openchrome.org/trac/ticket/371>
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