* DMA memory from block layer vs pci_alloc_consistent
@ 2018-12-27 21:31 Kieran Kunhya
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From: Kieran Kunhya @ 2018-12-27 21:31 UTC (permalink / raw)
To: linux-block
Hello,
I’ve been reverse engineering Sony SxS memory cards, which are simple
PCIe based block devices. I am able to read successfully from the
device with DMA memory allocated using pci_alloc_consistent and
memcpying to the buffer the block device layer provides.
But if I use the dma_addr_t provided by the block device DMA layer, I
get a soft lockup. Is there something special about the dma_addr_t
that comes from the block layer? Is there anything I need to do to it
before passing it to the hardware.
The device’s block size is 2048, the block layer reads two blocks at a time.
Memcpy code is here:
https://github.com/kierank/sxs-linux/blob/master/sxs.c#L98
DMA code is here:
https://github.com/kierank/sxs-linux/blob/dma/sxs.c#L101
Apologies for the untidiness of the code, it’s entirely reverse engineered.
Any help would be appreciated.
Kieran
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