Hi Geert, Thank you for the patch. On Mon, Jan 11, 2021 at 01:57:02PM +0100, Geert Uytterhoeven wrote: > As nwl_dsi.lanes is u32, and NSEC_PER_SEC is 1000000000L, the second > multiplication in > > dsi->lanes * 8 * NSEC_PER_SEC > > will overflow on a 32-bit platform. Fix this by making the constant > unsigned long long, forcing 64-bit arithmetic. > > While iMX8 is arm64, this driver is currently used on 64-bit platforms > only, where long is 64-bit, so this cannot happen. But the issue may > start to happen when the driver is reused for a 32-bit SoC, or when code > is copied for a new driver. > > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx> > --- > Compile-tested only. > --- > drivers/gpu/drm/bridge/nwl-dsi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c > index 66b67402f1acd57d..a8da3081efdcc84e 100644 > --- a/drivers/gpu/drm/bridge/nwl-dsi.c > +++ b/drivers/gpu/drm/bridge/nwl-dsi.c > @@ -195,7 +195,7 @@ static u32 ps2bc(struct nwl_dsi *dsi, unsigned long long ps) > u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format); > > return DIV64_U64_ROUND_UP(ps * dsi->mode.clock * bpp, > - dsi->lanes * 8 * NSEC_PER_SEC); > + dsi->lanes * 8ULL * NSEC_PER_SEC); I wonder if we could get rid of a whole class of bugs by turning NSEC_PER_SEC into a ULL, but I suppose there are valid cases where a 32-bit integer is enough. Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> How did you come across this by the way ? > } > > /* -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
