Hi Kishon, On Fri, Mar 20, 2020 at 5:28 AM Kishon Vijay Abraham I <kishon@xxxxxx> wrote: > > Hi Prabhakar, > > On 3/18/2020 5:07 PM, Lad, Prabhakar wrote: > > Hi Kishon, > > > > I rebased my rcar-endpoint patches on endpoint branch, which has > > support for streaming DMA API support, with this read/write/copy > > tests failed, to make sure nothing hasn't changed on my driver I > > reverted the streaming DMA API patch > > 74b9b4da84c71418ceeaaeb78dc790376df92fea "misc: pci_endpoint_test: Use > > streaming DMA APIs for buffer allocation" and tests began to pass > > again. > > > > If add a GFP_DMA flag for kzalloc (with streaming DMA), the test cases > > for read/write/copy pass as expected. > > > > Could you please through some light why this could be happening. > > Do you see any differences in the address returned by dma_map_single() like is > it 32-bit address or 64-bit address? > Both return 32 bit address, debugging further I see that with GFP_KERNEL flag for small buffer sizes the read/write/copy tests pass(upto 4k), so I am suspecting its related to caching probably. Also adding wmb()/rmb() just with GFP_KERNEL flag didn't help. Note I am using PIO transfers. Any thoughts on how we tackle it ? # With GFP_KERNEL flag root@hihope-rzg2m:~# pcitest -r [ 46.210649] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff0004b4ae0000 dma:7e99d000 align:ffff0004b4ae0000 READ ( 102400 bytes): NOT OKAY root@hihope-rzg2m:~# pcitest -r [ 51.880063] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff0004b4ae0000 dma:7e9c0000 align:ffff0004b4ae0000 READ ( 102400 bytes): OKAY root@hihope-rzg2m:~# pcitest -r [ 53.354830] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff0004b4ae0000 dma:7e9e2000 align:ffff0004b4ae0000 READ ( 102400 bytes): NOT OKAY root@hihope-rzg2m:~# pcitest -r [ 55.307236] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff0004b4ae0000 dma:7ea04000 align:ffff0004b4ae0000 READ ( 102400 bytes): NOT OKAY root@hihope-rzg2m:~# pcitest -r [ 57.098626] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff0004b4ae0000 dma:7ea23000 align:ffff0004b4ae0000 READ ( 102400 bytes): NOT OKAY # GFP_KERNEL | GFP_DMA root@hihope-rzg2m:~# pcitest -r -s 1024001 [ 174.562071] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff00003b900000 dma:7b900000 align:ffff00003b900000 READ (1024001 bytes): OKAY root@hihope-rzg2m:~# pcitest -r -s 16384 [ 186.629347] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff00003b848000 dma:7b848000 align:ffff00003b848000 READ ( 16384 bytes): OKAY root@hihope-rzg2m:~# pcitest -r -s 8192 [ 190.578335] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff00003b840000 dma:7b840000 align:ffff00003b840000 READ ( 8192 bytes): OKAY root@hihope-rzg2m:~# pcitest -r -s 128 [ 199.428021] pci-endpoint-test 0000:01:00.0: pci_endpoint_test_read kzalloc:ffff00003b800000 dma:7b800000 align:ffff00003b800000 READ ( 128 bytes): OKAY root@hihope-rzg2m:~# Cheers, --Prabhakar > Thanks > Kishon
