Messages in this thread | | | From | Ard Biesheuvel <> | Date | Thu, 8 Feb 2018 09:54:38 +0000 | Subject | Re: [PATCH] spi: bcm2835aux: use 64-bit arithmetic instead of 32-bit |
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On 7 February 2018 at 16:00, Gustavo A. R. Silva <gustavo@embeddedor.com> wrote: > Add suffix ULL to constant 9 in order to give the compiler complete > information about the proper arithmetic to use. Notice that this > constant is used in a context that expects an expression of type > unsigned long long (64 bits, unsigned). > > The expression tfr->len * 9 * 1000000 is currently being evaluated > using 32-bit arithmetic. > > Addresses-Coverity-ID: 1339619
What does this number mean? If it is an index into some internal database, please remove it.
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/spi/spi-bcm2835aux.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c > index 7428091..a768c23 100644 > --- a/drivers/spi/spi-bcm2835aux.c > +++ b/drivers/spi/spi-bcm2835aux.c > @@ -363,7 +363,7 @@ static int bcm2835aux_spi_transfer_one(struct spi_master *master, > * chunk getting transferred - in our case the chunk size > * is 3 bytes, so we approximate this by 9 bits/byte > */ > - xfer_time_us = tfr->len * 9 * 1000000; > + xfer_time_us = tfr->len * 9ULL * 1000000; > do_div(xfer_time_us, spi_used_hz); > > /* run in polling mode for short transfers */ > -- > 2.7.4 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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