Re: Sandisk Compact Flash

somshekar.c.kadam_at_in.abb.com
Date: 07/20/05

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    To: dhinds@sonic.net
    Date:	Wed, 20 Jul 2005 12:48:59 +0530
    
    
    

    Hi David ,

        On my controller CF INPACK pin is connected to 3.3v. so Comapct flash
    with DMA capabilty will not be supported , i understood this .
    but i did not undesrtand why only PIO mode 1 is supported is it , why not
    PIO mode 4 , is it a limitation of pcmcia driver , correct me if i am wrong

    Thanks In Advance
    Somshekar

                                                                                                         
     (Embedded David Hinds <dhinds@sonic.net>
     image moved 07/15/2005 10:51 AM
     to file:
     pic05705.pcx)
                                                                                                         
                                                                                                         

    To: somshekar.c.kadam@in.abb.com
    cc: linux-kernel@vger.kernel.org
    Subject: Re: Sandisk Compact Flash

    Security Level:? Internal

    On Wed, Jul 13, 2005 at 07:04:38PM +0530, somshekar.c.kadam@in.abb.com
    wrote:
    >
    > I ma newbie to compactflash driver , I am using mpc862 PPC processor
    > on my custom board having 64mb ram running linuxppc-2.4.18 kernel .
    > i am using Sandisk Extreme CF 1GB which is 133x high speed, but
    > found the performance with other kingston 1GB CF with slower speed ,
    > is both same , CF is implemented on pcmcia port , i am not sure what
    > is the mode set for transfer , Feature set command is used in which
    > it sets the PIO mode or Multiword DMA transfer mode by specifying
    > its value in Sector count register , i am not able to understand in
    > linux kernel ide driver where this is set , is it by default set ,
    > this mode is set or we need to set it , i think we should assign
    > this value , right now i am not able to trace this in my code. ,

    All Compact Flash cards, in 16-bit PCMCIA card readers, operate in PIO
    mode 1 (polled IO, no DMA), which means you will get only about 1
    MB/sec regardless of the card's claimed tranfer speed. Some cameras
    also only support this mode; others will run CF cars in "TrueIDE"
    mode, which is required to use the DMA transfer modes.

    There are high performance CF card readers that can use TrueIDE mode:
    both CardBus ones and Firewire ones. For example:

    http://www.dpreview.com/news/0310/03102103delkincardbustest.asp

    It sounds like your card reader is one of the slow 16-bit ones.

    -- Dave

    
    

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