[vdr] Re: Increasing SDRAM on DVB cards

[Stefaan Coddé <stefaan.codde@pandora.be>]

Klaus Schmidinger wrote:



>Hermann Gausterer wrote:
>>
>> > The card has 2MB of DRAM (which is relatively slow) and 2MB of 
>> > (fast) SDRAM. The SDRAM is the one used for video decoding (buffer)

>> > and OSD.
>> 
>> what are the adress ranges the two consume in the "virtual" rammap of

>> the DSP? are the close to another? (i think you have access to the 
>> firmware-source, and know this, klaus *sfg*)

>Take a look at page 13 of the AV7110 data sheet, which shows its memory
map. The SDRAM is at CC000000-CDFFFFFF, while the >DRAM is at
2E000000-2FFFFFFF.

>> the reason for my question:
>> i think the easiest way for doing this what you want to do is,
replace 
>> the chip with an pincompable type with more capacity
>> 
>> accourding to the docs, brought to us by Stefaan Coddé (thank you !!)

>> the dram chip has 11 adress lines and they are used in the form:
>> 
>> A 0 - A 10
>> R o w   A d d r e s s   :   R A 0   ~   R A 1 0 ,   C o l u m n   A d
d r e
>> s s   :   C A 0   ~   C A 7
>> A u t o - p r e c h a r g e   f l a g   :   A 1 0
>> 
>> but the CHIP (the DIL housing) has allready forseen an A 11
>> 
>> for this layout, it is clear that A0 - A10 MUST be allready wired to 
>> the DSP and if we/you get an replacing part, simple look for an which

>> can do on bit more on the COLUMN mode and you have your 4mb
>> 
>> for this to work, the hardware adressdecoder for the two different
ram 
>> chips have to be a GAP between DRAM and SRAM
>> 
>> this layout is only guesed, for explanation only !!!!!
>> 
>> 0FFF:FFFF----------------------(x+2 mb)
>> ###########    SRAM   #########
>> 0FE0:0000----------------------(x mb)
>> 
>> 003F:FFFF----------------------(4 mb)
>> #######  DRAM FUTURE !!! ###### 001F:FFFF----------------------(2 mb)
>> ###########    DRAM   #########
>> 0000:0000----------------------(0 mb)
>> 
>> with this no change to the hardware decoder would be needed but only 
>> somebody with knowledge of the firmewareinternals can answer and help

>> here !

>Well, since SDRAM goes from CC000000-CDFFFFFF and only half of that
address space
>is currently used, your suggestion might >work _if_ there are actually
enough 
>address lines connected. However, since the AV7110 has two explicit SCS
lines 
>(SCS1 and SCS2) I would assume that it can handle either one or two 2MB
chips,
> each connected to its very own SCSn line.

>But I'm just guessing here... Maybe you're actually on the right track.
>But then again, what would the SCS2 pin be for?

We really need more detailed info on the DSP.

IF the DSP can adress the entire range between CC000000-CDFFFFFF so not
mentioned as two
2MB blocks and the DSP's adress bus is wide enough to adress the 4MB
block
then the available chip select line is enough.

It's not abnormal that a DSP offers two ways to connect ram onto the
device.
Unfortunatly, it might be not so easy to find a suitable 32Mbit chip and
if a 16Mbit is used,
then you need chip select line 2 to use it.
64mbit chips are easy to find but usual in 54 pin housings so too big.

So it might be a good idea to focus on the extra adres lines too cause
that seems
a more easy way, unless the second chip select is easy to catch for.

Note at Klaus:

Let's assume that a card has 4Mbyte , for what whould you use it for?




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