| Message ID | 20200527133543.599948-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | drm/msm/dpu: avoid open-coded 64-bit division | expand |
On 27.05.20 16:35, Arnd Bergmann wrote: > 64-bit integer division is normally not allowed in the kernel > because of the large overhead on 32-bit machines: > > drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.o: in function `_dpu_core_perf_crtc_update_bus': > dpu_core_perf.c:(.text+0x810): undefined reference to `__aeabi_uldivmod' > > The function already contains a call to do_div(), so I assume this > is never called in a performance critical context, and we can > use div_u64 for the second one as well. > > Fixes: 04d9044f6c57 ("drm/msm/dpu: add support for clk and bw scaling for display") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Georgi Djakov <georgi.djakov@linaro.org> Thanks for the patch Arnd. I just noticed this in linux-next. Rob, could you please take it into msm-next, as the patch which triggers the issue is also there? Thanks, Georgi > --- > include/linux/interconnect.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h > index 3a63d98613fc..8279fe9b2082 100644 > --- a/include/linux/interconnect.h > +++ b/include/linux/interconnect.h > @@ -11,7 +11,7 @@ > #include <linux/types.h> > > /* macros for converting to icc units */ > -#define Bps_to_icc(x) ((x) / 1000) > +#define Bps_to_icc(x) div_u64((x), 1000) > #define kBps_to_icc(x) (x) > #define MBps_to_icc(x) ((x) * 1000) > #define GBps_to_icc(x) ((x) * 1000 * 1000) >
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h index 3a63d98613fc..8279fe9b2082 100644 --- a/include/linux/interconnect.h +++ b/include/linux/interconnect.h @@ -11,7 +11,7 @@ #include <linux/types.h> /* macros for converting to icc units */ -#define Bps_to_icc(x) ((x) / 1000) +#define Bps_to_icc(x) div_u64((x), 1000) #define kBps_to_icc(x) (x) #define MBps_to_icc(x) ((x) * 1000) #define GBps_to_icc(x) ((x) * 1000 * 1000)
64-bit integer division is normally not allowed in the kernel because of the large overhead on 32-bit machines: drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.o: in function `_dpu_core_perf_crtc_update_bus': dpu_core_perf.c:(.text+0x810): undefined reference to `__aeabi_uldivmod' The function already contains a call to do_div(), so I assume this is never called in a performance critical context, and we can use div_u64 for the second one as well. Fixes: 04d9044f6c57 ("drm/msm/dpu: add support for clk and bw scaling for display") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- include/linux/interconnect.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)