On 24-02-22, 04:23, Akhil R wrote: > > On Wed, Feb 23, 2022 at 03:49:09AM +0000, Akhil R wrote: > > > I am getting notification for the below warning also. > > > > > > >> drivers/dma/tegra186-gpc-dma.c:898:53: warning: shift count >= width of > > type [-Wshift-count-overflow] > > > FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> > > 32)); > > > https://lore.kernel.org/all/202202230559.bLOEMEUh-lkp@xxxxxxxxx/ > > > > > > I suppose, this is because it is compiled against a different ARCH other than > > arm64. > > > For arm64, the dma_addr_t is 64 bytes, and this warning does not occur. > > > Could this be ignored for now? If not, could you suggest a fix, if possible? > > > > I am not really familiar with the DMA API and dma_addr_t so I am not > > sure about a proper fix. > > > > You could cast dest to u64 to guarantee it is a type that can be shifted > > by 32 but that might not be right for CONFIG_PHYS_ADDR_T_64BIT=n. If the > > driver is not expected to run without CONFIG_PHYS_ADDR_T_64BIT, then > > this is probably fine. > > > > You could mark this driver 'depends on PHYS_ADDR_T_64BIT' if it cannot > > run with CONFIG_ARCH_TEGRA=y + CONFIG_PHYS_ADDR_T_64BIT=n but I do > > not > > see any other drivers that do that, which might mean that is not a > > proper fix. > > > > Please do not ignore the warning, as it will show up with ARCH=arm > > allmodconfig, which has -Werror enabled. > I see some drivers using 'depends on ARM64'. I guess probably we could > use that to avoid this warning. The driver is only supported for arm64 Tegra > systems as of now. dma_addr_t can be different on different arch so yes this 'can' overflow, but since this driver would never be used on non ARM64, make sense to put depends. -- ~Vinod
