From: Paul Walmsley <paul.walmsley@sifive.com>
To: Nicolas Pitre <nico@fluxnic.net>
Cc: linux-riscv@lists.infradead.org,
Palmer Dabbelt <palmer@sifive.com>,
Alan Kao <alankao@andestech.com>
Subject: Re: [PATCH] RISC-V: Remove udivdi3
Date: Tue, 6 Aug 2019 19:40:27 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.9999.1908061936300.25231@viisi.sifive.com> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1908062230570.19480@knanqh.ubzr>
On Tue, 6 Aug 2019, Nicolas Pitre wrote:
> On Tue, 6 Aug 2019, Paul Walmsley wrote:
>
> > This patch breaks the rv32_defconfig build, since udelay() still relies on
> > __udivdi3(). I'll queue "riscv: delay: use do_div() instead of
> > __udivdi3()" along with it:
> >
> > https://lore.kernel.org/linux-riscv/alpine.DEB.2.21.9999.1908061906240.25231@viisi.sifive.com/T/#u
>
> > + u64 n;
> > + u32 rem;
> >
> > if (unlikely(usecs > MAX_UDELAY_US)) {
> > - __delay((u64)usecs * riscv_timebase / 1000000ULL);
> > + n = (u64)usecs * riscv_timebase;
> > + rem = do_div(n, 1000000);
>
> You may omit rem and ignore the return value here.
Thanks Nico. Updated patch below
- Paul
From: Paul Walmsley <paul.walmsley@sifive.com>
Date: Tue, 6 Aug 2019 18:28:33 -0700
Subject: [PATCH] riscv: delay: use do_div() instead of __udivdi3()
In preparation for removing __udivdi3() from the RISC-V
architecture-specific files, convert its one user to use do_div().
This avoids breaking the RV32 build after __udivdi3() is removed.
This second version removes the assignment of the remainder to an
unused temporary variable. Thanks to Nicolas Pitre <nico@fluxnic.net>
for the suggestion.
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
---
arch/riscv/lib/delay.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/lib/delay.c b/arch/riscv/lib/delay.c
index 87ff89e88f2c..f51c9a03bca1 100644
--- a/arch/riscv/lib/delay.c
+++ b/arch/riscv/lib/delay.c
@@ -81,9 +81,13 @@ EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs)
{
u64 ucycles = (u64)usecs * lpj_fine * UDELAY_MULT;
+ u64 n;
if (unlikely(usecs > MAX_UDELAY_US)) {
- __delay((u64)usecs * riscv_timebase / 1000000ULL);
+ n = (u64)usecs * riscv_timebase;
+ do_div(n, 1000000);
+
+ __delay(n);
return;
}
--
2.22.0
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
prev parent reply other threads:[~2019-08-07 2:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 0:05 [PATCH] RISC-V: Remove udivdi3 Palmer Dabbelt
2019-08-07 0:18 ` Alan Kao
2019-08-07 0:38 ` Paul Walmsley
2019-08-07 2:09 ` Paul Walmsley
2019-08-07 2:33 ` Nicolas Pitre
2019-08-07 2:40 ` Paul Walmsley [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.DEB.2.21.9999.1908061936300.25231@viisi.sifive.com \
--to=paul.walmsley@sifive.com \
--cc=alankao@andestech.com \
--cc=linux-riscv@lists.infradead.org \
--cc=nico@fluxnic.net \
--cc=palmer@sifive.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).