On 28.10.2024 10:52 AM, Akhil P Oommen wrote: > On 10/28/2024 12:13 AM, Arnd Bergmann wrote: >> On Sun, Oct 27, 2024, at 18:05, Akhil P Oommen wrote: >>> Clang-19 and above sometimes end up with multiple copies of the large >>> a6xx_hfi_msg_bw_table structure on the stack. The problem is that >>> a6xx_hfi_send_bw_table() calls a number of device specific functions to >>> fill the structure, but these create another copy of the structure on >>> the stack which gets copied to the first. >>> >>> If the functions get inlined, that busts the warning limit: >>> >>> drivers/gpu/drm/msm/adreno/a6xx_hfi.c:631:12: error: stack frame size >>> (1032) exceeds limit (1024) in 'a6xx_hfi_send_bw_table' >>> [-Werror,-Wframe-larger-than] >>> >>> Fix this by kmalloc-ating struct a6xx_hfi_msg_bw_table instead of using >>> the stack. Also, use this opportunity to skip re-initializing this table >>> to optimize gpu wake up latency. >>> >>> Cc: Arnd Bergmann <arnd@xxxxxxxxxx> >> >> Please change this to "Reported-by:" > > Sure. > >> >> The patch looks correct to me, just one idea for improvement. >> >>> b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >>> index 94b6c5cab6f4..b4a79f88ccf4 100644 >>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >>> @@ -99,6 +99,7 @@ struct a6xx_gmu { >>> struct completion pd_gate; >>> >>> struct qmp *qmp; >>> + struct a6xx_hfi_msg_bw_table *bw_table; >>> }; >> >> I think the bw_table is better just embedded >> in here rather than referenced as a pointer: >> > There are some low tier chipsets with relatively lower RAM size that > doesn't require this table. So, dynamically allocating this here helps > to save 640 bytes (minus the overhead of tracking). I'd second this, said chipsets often ship with 1-2 GiB of RAM (which is still a lot in comparison, but you know.. every little bit counts) Konrad