On Thu, Aug 3, 2023 at 9:01 PM Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote: > > Hi-- > > On 8/3/23 08:24, Adam Ford wrote: > > On Thu, Aug 3, 2023 at 9:42 AM Aleksandr Nogikh <nogikh@xxxxxxxxxx> wrote: > >> > >> Hello, > >> > >> We've been seing the following linker error on arm64 syzbot instances: > >> > >> ld.lld: error: undefined symbol: phy_mipi_dphy_get_default_config_for_hsclk > >>>>> referenced by samsung-dsim.c:731 (drivers/gpu/drm/bridge/samsung-dsim.c:731) > >>>>> drivers/gpu/drm/bridge/samsung-dsim.o:(samsung_dsim_init) in archive vmlinux.a > >> > >> Steps to reproduce on the latest linux-next: > >> > >> $ git checkout next-20230803 > >> $ wget -O '.config' 'https://raw.githubusercontent.com/google/syzkaller/master/dashboard/config/linux/upstream-arm64-kasan.config' > >> $ make CC=clang ARCH=arm64 LD=ld.lld CROSS_COMPILE=aarch64-linux-gnu- olddefconfig > >> > >> This also prints: > >> > >> WARNING: unmet direct dependencies detected for GENERIC_PHY_MIPI_DPHY > >> Depends on [n]: GENERIC_PHY [=n] > >> Selected by [y]: > >> - DRM_NWL_MIPI_DSI [=y] && DRM_BRIDGE [=y] && DRM [=y] && COMMON_CLK [=y] && OF [=y] && HAS_IOMEM [=y] > >> - DRM_SAMSUNG_DSIM [=y] && DRM [=y] && DRM_BRIDGE [=y] && COMMON_CLK [=y] && OF [=y] && HAS_IOMEM [=y] > >> > >> $ make CC=clang ARCH=arm64 LD=ld.lld CROSS_COMPILE=aarch64-linux-gnu- -j$(nproc) > >> > >> The kernel should have still compiled fine even despite the message above, right? > > No. See drivers/Makefile: > obj-$(CONFIG_GENERIC_PHY) += phy/ > > so the drivers/phy/ subdir is only built when CONFIG_GENERIC_PHY is set, > but it's not set. > > >> Could you please take a look? > > > > GENERIC_PHY_MIPI_DPHY was enabled to use > > phy_mipi_dphy_get_default_config() which takes in the pixel clock, > > bits-per-pixel, number of lanes and phy structure. It applies a bunch > > of math based on the info passed and fills in the structure, but that > > function itself doesn't appear to be referencing phy code, so it's > > likely safe. > > > > I think this can be resolved by enabling GENERIC_PHY. I just checked > > linux-next and when I built the arm64 defconfig, it enables > > GENERIC_PHY=y, so I don't think this is an issue. I also checked the > > defconfig doesn't matter in this case. The .config that was provided has: > # CONFIG_GENERIC_PHY is not set > CONFIG_GENERIC_PHY_MIPI_DPHY=y > Where/how was the .config generated? Are you building linux-next or something else? The .config file generated when I build the arm64 defconfig show both enabled: $ grep GENERIC_PHY .config CONFIG_GENERIC_PHY=y CONFIG_GENERIC_PHY_MIPI_DPHY=y > but yes, selecting GENERIC_PHY (needed in 3 places) does fix the warnings > and build error. 2 instance in drm/bridge/Kconfig and one in > drm/bridge/cadence/Kconfig (found by inspection). > > > > > multi_v7_defconfig for ARM and it also sets GENERIC_PHY=y for 32-bit > > ARM people using some of the Exynos boards. > > > > I don't know what version of Linux you're trying to build, but I can't > > replicate your issue. > > I had no problem replicating the kconfig warnings and build error. If you can replicate the problem, I'd suggest submitting a patch. adam > > -- > ~Randy
