drm/rockchip: avoid 64-bit division

[PATCH] drm/rockchip: avoid 64-bit division

Posted by Arnd Bergmann 1 month, 1 week ago

From: Arnd Bergmann <arnd@arndb.de>

Dividing a 64-bit integer prevents building this for 32-bit targets:

ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!

As this function is not performance criticial, just Use the div_u64() helper.

Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
index 9c796ee4c303..c8b362cc2b95 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
@@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
 		 * comment in rk_hdptx_phy_power_on() from
 		 * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
 		 */
-		phy_set_bus_width(hdmi->phy, rate / 100);
+		phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
 	}
 }
 
-- 
2.39.5

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Nathan Chancellor 3 weeks ago

On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Dividing a 64-bit integer prevents building this for 32-bit targets:
> 
> ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> 
> As this function is not performance criticial, just Use the div_u64() helper.
> 
> Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

Can someone please pick this up? It is still broken in next-20241104...

https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2oNvJFRj8tkDieb6VfrMf4rh1Kn/build.log

> ---
>  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> index 9c796ee4c303..c8b362cc2b95 100644
> --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> @@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
>  		 * comment in rk_hdptx_phy_power_on() from
>  		 * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
>  		 */
> -		phy_set_bus_width(hdmi->phy, rate / 100);
> +		phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
>  	}
>  }
>  
> -- 
> 2.39.5
>

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Geert Uytterhoeven 4 days ago

On Mon, Nov 4, 2024 at 6:30 PM Nathan Chancellor <nathan@kernel.org> wrote:
> On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Dividing a 64-bit integer prevents building this for 32-bit targets:
> >
> > ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> >
> > As this function is not performance criticial, just Use the div_u64() helper.
> >
> > Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> Can someone please pick this up? It is still broken in next-20241104...
>
> https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2oNvJFRj8tkDieb6VfrMf4rh1Kn/build.log
>
> > ---
> >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > index 9c796ee4c303..c8b362cc2b95 100644
> > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > @@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
> >                * comment in rk_hdptx_phy_power_on() from
> >                * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> >                */
> > -             phy_set_bus_width(hdmi->phy, rate / 100);
> > +             phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
> >       }
> >  }

noreply@ellerman.id.au has just told me this build issue is now upstream:

    FAILED linus/m68k-allmodconfig/m68k-gcc8.1 Fri Nov 22, 05:34
    http://kisskb.ellerman.id.au/kisskb/buildresult/15277242/

    Commit:   Merge tag 'drm-next-2024-11-21' of
https://gitlab.freedesktop.org/drm/kernel
              28eb75e178d389d325f1666e422bc13bbbb9804c
    Compiler: m68k-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30

    ERROR: modpost: "__udivdi3"
[drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!

Applying this patch fixes it, so
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

Do we really need +5 weeks to apply a fix for a reported build issue?
Thanks!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Maxime Ripard 3 days, 23 hours ago

On Fri, Nov 22, 2024 at 09:36:16AM +0100, Geert Uytterhoeven wrote:
> On Mon, Nov 4, 2024 at 6:30 PM Nathan Chancellor <nathan@kernel.org> wrote:
> > On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> > > From: Arnd Bergmann <arnd@arndb.de>
> > >
> > > Dividing a 64-bit integer prevents building this for 32-bit targets:
> > >
> > > ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> > >
> > > As this function is not performance criticial, just Use the div_u64() helper.
> > >
> > > Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >
> > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> >
> > Can someone please pick this up? It is still broken in next-20241104...
> >
> > https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2oNvJFRj8tkDieb6VfrMf4rh1Kn/build.log
> >
> > > ---
> > >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > index 9c796ee4c303..c8b362cc2b95 100644
> > > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > @@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
> > >                * comment in rk_hdptx_phy_power_on() from
> > >                * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> > >                */
> > > -             phy_set_bus_width(hdmi->phy, rate / 100);
> > > +             phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
> > >       }
> > >  }
> 
> noreply@ellerman.id.au has just told me this build issue is now upstream:
> 
>     FAILED linus/m68k-allmodconfig/m68k-gcc8.1 Fri Nov 22, 05:34
>     http://kisskb.ellerman.id.au/kisskb/buildresult/15277242/
> 
>     Commit:   Merge tag 'drm-next-2024-11-21' of
> https://gitlab.freedesktop.org/drm/kernel
>               28eb75e178d389d325f1666e422bc13bbbb9804c
>     Compiler: m68k-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30
> 
>     ERROR: modpost: "__udivdi3"
> [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> 
> Applying this patch fixes it, so
> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
> 
> Do we really need +5 weeks to apply a fix for a reported build issue?

Do we really need that kind of comments?

It was applied already, I made sure it's part of the next PR we send to
Linus. And it should be in linux-next tomorrow.

Maxime

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Geert Uytterhoeven 22 hours ago

Hi Maxime,

On Fri, Nov 22, 2024 at 10:15 AM Maxime Ripard <mripard@kernel.org> wrote:
> On Fri, Nov 22, 2024 at 09:36:16AM +0100, Geert Uytterhoeven wrote:
> > On Mon, Nov 4, 2024 at 6:30 PM Nathan Chancellor <nathan@kernel.org> wrote:
> > > On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> > > > From: Arnd Bergmann <arnd@arndb.de>
> > > >
> > > > Dividing a 64-bit integer prevents building this for 32-bit targets:
> > > >
> > > > ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> > > >
> > > > As this function is not performance criticial, just Use the div_u64() helper.
> > > >
> > > > Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > >
> > > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> > >
> > > Can someone please pick this up? It is still broken in next-20241104...
> > >
> > > https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2oNvJFRj8tkDieb6VfrMf4rh1Kn/build.log
> > >
> > > > ---
> > > >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > index 9c796ee4c303..c8b362cc2b95 100644
> > > > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > @@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
> > > >                * comment in rk_hdptx_phy_power_on() from
> > > >                * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> > > >                */
> > > > -             phy_set_bus_width(hdmi->phy, rate / 100);
> > > > +             phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
> > > >       }
> > > >  }
> >
> > noreply@ellerman.id.au has just told me this build issue is now upstream:
> >
> >     FAILED linus/m68k-allmodconfig/m68k-gcc8.1 Fri Nov 22, 05:34
> >     http://kisskb.ellerman.id.au/kisskb/buildresult/15277242/
> >
> >     Commit:   Merge tag 'drm-next-2024-11-21' of
> > https://gitlab.freedesktop.org/drm/kernel
> >               28eb75e178d389d325f1666e422bc13bbbb9804c
> >     Compiler: m68k-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30
> >
> >     ERROR: modpost: "__udivdi3"
> > [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> >
> > Applying this patch fixes it, so
> > Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
> >
> > Do we really need +5 weeks to apply a fix for a reported build issue?
>
> Do we really need that kind of comments?
>
> It was applied already, I made sure it's part of the next PR we send to
> Linus. And it should be in linux-next tomorrow.

Thank you, I can confirm it is now commit 818956c76517e127
("drm/rockchip: avoid 64-bit division") in drm-misc/for-linux-next
and next-20241125.

Interestingly, the commit description contains:

    (cherry picked from commit 4b64b4a81fcd51f570c046cf904aef19ec756d45)

which is not in any tree on git.kernel.org, but the github collective
does know about it:
https://github.com/torvalds/linux/commit/4b64b4a81fcd51f570c046cf904aef19ec756d45

Probably you want to drop that line.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Geert Uytterhoeven 3 days, 23 hours ago

Hi Maxime,

On Fri, Nov 22, 2024 at 10:15 AM Maxime Ripard <mripard@kernel.org> wrote:
> On Fri, Nov 22, 2024 at 09:36:16AM +0100, Geert Uytterhoeven wrote:
> > On Mon, Nov 4, 2024 at 6:30 PM Nathan Chancellor <nathan@kernel.org> wrote:
> > > On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> > > > From: Arnd Bergmann <arnd@arndb.de>
> > > >
> > > > Dividing a 64-bit integer prevents building this for 32-bit targets:
> > > >
> > > > ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> > > >
> > > > As this function is not performance criticial, just Use the div_u64() helper.
> > > >
> > > > Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > >
> > > Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> > >
> > > Can someone please pick this up? It is still broken in next-20241104...
> > >
> > > https://storage.tuxsuite.com/public/clangbuiltlinux/continuous-integration2/builds/2oNvJFRj8tkDieb6VfrMf4rh1Kn/build.log
> > >
> > > > ---
> > > >  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > index 9c796ee4c303..c8b362cc2b95 100644
> > > > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c
> > > > @@ -82,7 +82,7 @@ static void dw_hdmi_qp_rockchip_encoder_enable(struct drm_encoder *encoder)
> > > >                * comment in rk_hdptx_phy_power_on() from
> > > >                * drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
> > > >                */
> > > > -             phy_set_bus_width(hdmi->phy, rate / 100);
> > > > +             phy_set_bus_width(hdmi->phy, div_u64(rate, 100));
> > > >       }
> > > >  }
> >
> > noreply@ellerman.id.au has just told me this build issue is now upstream:
> >
> >     FAILED linus/m68k-allmodconfig/m68k-gcc8.1 Fri Nov 22, 05:34
> >     http://kisskb.ellerman.id.au/kisskb/buildresult/15277242/
> >
> >     Commit:   Merge tag 'drm-next-2024-11-21' of
> > https://gitlab.freedesktop.org/drm/kernel
> >               28eb75e178d389d325f1666e422bc13bbbb9804c
> >     Compiler: m68k-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30
> >
> >     ERROR: modpost: "__udivdi3"
> > [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> >
> > Applying this patch fixes it, so
> > Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
> >
> > Do we really need +5 weeks to apply a fix for a reported build issue?
>
> Do we really need that kind of comments?

Perhaps not...

> It was applied already,

Where was it applied?
How would I know that, when the fix is not in linux-next?

> I made sure it's part of the next PR we send to
> Linus. And it should be in linux-next tomorrow.

Thank you!

The issue is that the reported build issue was not fixed in linux-next,
despite the fix having been available for 5 weeks, thus reducing
(build) test coverage for all affected architectures, possibly hiding
other issues.
In addition, a PR including the build issue was sent to Linus, so now
the above applies to Linus' tree, too.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] drm/rockchip: avoid 64-bit division

Posted by Dmitry Baryshkov 1 month, 1 week ago

On Fri, Oct 18, 2024 at 03:10:10PM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> Dividing a 64-bit integer prevents building this for 32-bit targets:
> 
> ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!
> 
> As this function is not performance criticial, just Use the div_u64() helper.
> 
> Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

-- 
With best wishes
Dmitry