On 8/3/23 19:26, Adam Ford wrote: > 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? > Aleksandr posted a link to the config file above. > Are you building linux-next or something else? The .config file > generated when I build the arm64 defconfig show both enabled: linux-next. > $ grep GENERIC_PHY .config > CONFIG_GENERIC_PHY=y > CONFIG_GENERIC_PHY_MIPI_DPHY=y > Yes, this is not a defconfig file. > >> 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. Sure, I'll do that. -- ~Randy
