[TAK2064]

Hi,

I am working on Cortex-A8 for my Application development.
Since OS I am using does not support MMU, I have created page table and configured MMU. I have configured the entire DDR as Cacheable (Write Through). The other region in the Memory space is defined as Non-cacheable.

For Invalidation I have followed Set / Way Method. The Other is MVA (Modified Virtual Address, I am not aware of Using it).

My Application has many DMA operations. So whenever a DMA occurs, I need to Invalidate the Cache. I am invalidating the entire Cache by Set/Way method.

But the invalidation of the entire cache consumes around 800uS, which can no where be compromised in my Application. Bcoz DMA may occur for even 32KB. But I will be invalidating the entire Cache; so eventually I will loose the Data in Cache and needs refiling again.

Im invalidating the Entire Cache, Since I don't know which Cache line (Block) would have been updated with this particular address (filled by DMA Data).

Is MVA a better process that I can follow to Invalidate the cache?? How can I use it to invalidate the Cache at a particular Address??

[zerojin]

TAK2064, on Apr 3 2010, 08:33 AM, said:

Hi,

I am working on Cortex-A8 for my Application development.
Since OS I am using does not support MMU, I have created page table and configured MMU. I have configured the entire DDR as Cacheable (Write Through). The other region in the Memory space is defined as Non-cacheable.

For Invalidation I have followed Set / Way Method. The Other is MVA (Modified Virtual Address, I am not aware of Using it).

My Application has many DMA operations. So whenever a DMA occurs, I need to Invalidate the Cache. I am invalidating the entire Cache by Set/Way method.

But the invalidation of the entire cache consumes around 800uS, which can no where be compromised in my Application. Bcoz DMA may occur for even 32KB. But I will be invalidating the entire Cache; so eventually I will loose the Data in Cache and needs refiling again.

Im invalidating the Entire Cache, Since I don't know which Cache line (Block) would have been updated with this particular address (filled by DMA Data).

Is MVA a better process that I can follow to Invalidate the cache?? How can I use it to invalidate the Cache at a particular Address??

I don't know well OS.
If you want us DMA, you have to Non-cacheable area for DMA.
At the Linux, you could refer the dma-mapping.c (arch/arm/mm/dma-mapping.c)

[TAK2064]

zerojin, on Apr 3 2010, 01:21 AM, said:

I don't know well OS.
If you want us DMA, you have to Non-cacheable area for DMA.
At the Linux, you could refer the dma-mapping.c (arch/arm/mm/dma-mapping.c)

Hi Zerojin,

Currently, I have tried with MVA invalidation to invalidate the Blocks after DMA.
But even this eventually adds up a delay.
Thanks for the Input. I will try the same at my end.

[Raghavendra]

TAK2064, on Apr 3 2010, 06:03 AM, said:

Hi,

I am working on Cortex-A8 for my Application development.
Since OS I am using does not support MMU, I have created page table and configured MMU. I have configured the entire DDR as Cacheable (Write Through). The other region in the Memory space is defined as Non-cacheable.

For Invalidation I have followed Set / Way Method. The Other is MVA (Modified Virtual Address, I am not aware of Using it).

My Application has many DMA operations. So whenever a DMA occurs, I need to Invalidate the Cache. I am invalidating the entire Cache by Set/Way method.

But the invalidation of the entire cache consumes around 800uS, which can no where be compromised in my Application. Bcoz DMA may occur for even 32KB. But I will be invalidating the entire Cache; so eventually I will loose the Data in Cache and needs refiling again.

Im invalidating the Entire Cache, Since I don't know which Cache line (Block) would have been updated with this particular address (filled by DMA Data).

Is MVA a better process that I can follow to Invalidate the cache?? How can I use it to invalidate the Cache at a particular Address??

Hi,
I'm also working with CortexA8. I have a problem in enabling MMU. I don't know how to create Page table and configure MMU. Can you just tell me how you have created Page Table and configured MMU.

Thanks & Regards,
M.Raghavendra.