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Hi, I am new to linux kernel development. I am working on a project, where i have developed a simple frame buffer driver for custom PCI express card. When X-server ...
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    Monitor goes into standby mode


    Hi,





    I am new to linux kernel development. I am working on a project, where i have developed a simple frame buffer driver for custom PCI express card.





    When X-server starts, I am able to see the graphics on the monitor connected to card. But monitor goes to standby mode(power saving mode). And it never gets back.





    After it goes to stand by mode, if i read or write to any memory location mapped by frame buffer driver, it fails.


    So, i checked the PCI configuration space, It showed me that Command register is set to Zero, Interrupt line register is set to FF and some register at location 0x76 in configuration space is changed from 0x00 to 0x64.





    So, when monitor was on, i tried to set those register with the value i got when monitor was in standby mode. With surprise, i found, there is no effect on the monitor from change of any of the above mentioned registers. Also, one strange thing happened was, I failed to change the register at 0x76 from 0x00 to 0x64.





    Below is the output of the lspci when monitor is working fine,





    02:00.0 Multimedia video controller: Unknown device 1a2a:1700 (rev 01)


    Subsystem: Infineon Technologies AG Unknown device 0011


    Flags: bus master, fast devsel, latency 0, IRQ 22


    Memory at 80000000 (32-bit, prefetchable) [size=512M]


    [virtual] Expansion ROM at fdd00000 [disabled] [size=128K]


    Capabilities: [40] Power Management version 3


    Capabilities: [50] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-


    Capabilities: [70] Express Endpoint IRQ 0


    00: 2a 1a 00 17 07 00 10 00 01 00 00 04 08 00 00 00


    10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    20: 00 00 00 00 08 00 00 80 00 00 00 00 d1 15 11 00


    30: 00 00 00 00 40 00 00 00 00 00 00 00 0a 01 00 00


    40: 01 50 c3 49 00 00 00 00 00 00 00 00 00 00 00 00


    50: 05 70 80 00 00 00 00 00 00 00 00 00 00 00 00 00


    60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    70: 10 00 02 00 00 87 00 00 10 20 01 00 11 3c 03 00


    80: 00 00 11 10 00 00 00 00 00 00 00 00 00 00 00 00


    90: 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00 00


    a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00








    And output of lspci when monitor is in standby mode





    02:00.0 Multimedia video controller: Unknown device 1a2a:1700 (rev 01)


    Subsystem: Infineon Technologies AG Unknown device 0011


    Flags: fast devsel, IRQ 22


    Memory at 80000000 (32-bit, prefetchable) [disabled] [size=512M]


    [virtual] Expansion ROM at fdd00000 [disabled] [size=128K]


    Capabilities: [40] Power Management version 3


    Capabilities: [50] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-


    Capabilities: [70] Express Endpoint IRQ 0


    00: 2a 1a 00 17 00 00 10 00 01 00 00 04 00 00 00 00


    10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    20: 00 00 00 00 08 00 00 00 00 00 00 00 d1 15 11 00


    30: 00 00 00 00 40 00 00 00 00 00 00 00 ff 01 00 00


    40: 01 50 c3 49 00 00 00 00 00 00 00 00 00 00 00 00


    50: 05 70 80 00 00 00 00 00 00 00 00 00 00 00 00 00


    60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    70: 10 00 02 00 00 87 64 00 10 20 0b 00 11 3c 03 00


    80: 00 00 11 10 00 00 00 00 00 00 00 00 00 00 00 00


    90: 00 00 00 00 10 00 00 00 00 00 00 00 00 00 00 00


    a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


    f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00





    Right now i am clueless. I don't know how to debug this issue further. If anyone has any idea please help me.





    I am using linux kernel 2.6.24.3 version with the patches of debian and ubuntu.





    Thanks


    Manish
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