> On Mon, Apr 11, 2022 at 03:59:05PM +0900, Wangseok Lee wrote: >> driver_init() -> >> -> platform_dma_configure() / platform.c >> |-> of_dma_configure() >> |-> of_dma_configure_id() >> :Here, set dma of 33+ address. >> dma_set_mask(0xf`ffff`ffff), bus_dma_limit(0xf`ffff`ffff) > > Where do we set a large than 32-bit dma mask here? I can't find the > code, and if there is we need to fix it. In Linux devices to come > up with 32-bit DMA masks for historical reasons (they really should > with a zero dma mask, but it is probably to lte to fix it). > >> -> artpec8_pcie_probe() / artpec-8 pcie driver code >> |-> dw_pcie_host_init() / pcie-designware-host.c >> |-> dma_set_mask(32) >> : Here, set the dma mask of 32 addresses. >> |-> dma_map_single_attrs() >> |-> dma_map_page_attrs() >> |-> dma_direct_map_page() >> : Error return occurs here. >> dma address has 33+ address and >> dma bus limit is 33+. >> However, this is because the mask value >> has 32 addresses. > > If the dma_mask is set to 32-bits, we should never generate a > large dma address, but bounce if it would othewise generate a > larger address. > > That being said I think this code would be much better off using > dma_alloc_coherent anyway. > >> Therefore, the dma_set_mask(32)(in dw_pcie_host_init()) >> was modified to be performed only when >> the dev-dma_mask is not set larger than 32 bits. > > So what sets dev->dma_mask to a larger than 32-bit value here? > We need to find and fix that. At the code of of_dma_configure_id() of driver/of/device.c.. In the 64bit system, if the dma start addr is used as 0x1'0000'0000 and the size is used as 0xf'0000'0000, "u64 end" is 0xf'ffff'ffff. And the dma_mask value is changed from 0xffff'ffff'ffff'ffff to 0xf'ffff'ffffff due to the code below. 181 line, driver/of/device.c ------------------------------------------------- end = dma_start + size - 1; mask = DMA_BIT_MASK(ilog2(end) + 1); dev->coherent_dma_mask &= mask; *dev->dma_mask &= mask; ------------------------------------------------- Please let me know if I'm mistaken. Thank you.
