Closed daloisio closed 3 years ago
Thank you for the issue.
To perform uncached reads, should i use the instructions to flush the cache or i should not because the CPU cache of allocated DMA buffer is disabled ? I specify the O_SYNC flag in mmap function.
Opening the device file with O_SYNC disables the CPU cache. When the CPU cache is disabled, there is no need to manually specify the cache flush & invalidate.
Thank you for your answer and help.
Best.
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From: KAWAZOME Ichiro notifications@github.com Sent: Friday, November 13, 2020 12:24:37 AM To: ikwzm/udmabuf udmabuf@noreply.github.com Cc: daloisio francesco_daloisio@hotmail.it; Author author@noreply.github.com Subject: Re: [ikwzm/udmabuf] Trying to perform DMA reads (#64)
Thank you for the issue.
To perform uncached reads, should i use the instructions to flush the cache or i should not because the CPU cache of allocated DMA buffer is disabled ? I specify the O_SYNC flag in mmap function.
Opening the device file with O_SYNC disables the CPU cache. When the CPU cache is disabled, there is no need to manually specify the cache flush & invalidate.
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HI,
I have no problems with your driver. I am only using it to perform 64 reads to DMA pages, i need to read 64 unchaced pages on CORTEX-A72 ARMv8. I edited the u-dma-buf_test.c a little bit. I simply added the following code:
and then i perform the reads of the pages within dma_page_buffer. To perform uncached reads, should i use the instructions to flush the cache or i should not because the CPU cache of allocated DMA buffer is disabled ? I specify the O_SYNC flag in mmap function. I wanted to make sure i am doing things in the right way.
Thank you.