Hi Kevin > > > + > > > +ifdef CONFIG_ARM64 > > > +KBUILD_CFLAGS += -mstrict-align > > > > > > There are many other drivers that do not use readl/writel for register access, > > yet none has this workaround... Even those that they are exclusively ARM64. > > > > Have you tried that it's not a buggy version of GCC? At the very least, I'd > > encourage you to add a brief comment about the problem + setup. > > > > ... In general I think one should follow the suggestions from Rob Herring. > > > Yocto v2.5 > aarch64-linaro-linux-gcc (Linaro GCC 7.2-2017.11) 7.2.1 20171011 > > Crash Stack: > /sprd/drv/dispc/dpu_r2p0.c:729 > 1796256 ffffff8008486650: f803c043 stur x3, [x2,#60] > =>Unhandled fault: alignment fault (0x96000061) at 0xffffff80098b883c > > 729 reg->mmu_min_ppn1 = 0; > 730 reg->mmu_ppn_range1 = 0xffff; > 731 reg->mmu_min_ppn2 = 0; > 732 reg->mmu_ppn_range2 = 0xffff; > > The above C code operation are continuous. The compiler may think that > the access can be completed by directly using two 64-bit assignment > operations, so it is optimized to 64-bit operation. What you see is a side-effect of using a sturct for register access. When you ave your code change to use readl()/writel() and friends this is no logner a problem, and you can drop the cc flag. Sam _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
