On 32-bit platforms using asm-generic/div64.h:
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c: In function 'gk20a_pllg_calc_rate':
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:79: warning: comparison of distinct pointer types lacks a cast
do_div(rate, divider);
^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:2: warning: right shift count >= width of type
do_div(rate, divider);
^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:238: warning: passing argument 1 of '__div64_32' from incompatible pointer type
do_div(rate, divider);
^
In file included from arch/parisc/include/generated/asm/div64.h:1:0,
from include/linux/kernel.h:124,
from include/linux/list.h:8,
from include/linux/preempt.h:10,
from include/linux/spinlock.h:50,
from include/linux/mmzone.h:7,
from include/linux/gfp.h:5,
from include/linux/slab.h:14,
from drivers/gpu/drm/nouveau/include/nvif/os.h:5,
from drivers/gpu/drm/nouveau/include/nvkm/core/os.h:3,
from drivers/gpu/drm/nouveau/include/nvkm/core/object.h:3,
from drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h:3,
from drivers/gpu/drm/nouveau/include/nvkm/subdev/clk.h:3,
from drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:25:
include/asm-generic/div64.h:35:17: note: expected 'uint64_t *' but argument is of type 'u32 *'
extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
^
do_div() is meant for 64-bit by 32-bit division, but both the dividend
and divisor are 32-bit here. Hence use plain "/" instead.
Signed-off-by: Geert Uytterhoeven <[email protected]>
---
Compile-tested only.
parisc/allmodconfig:
http://kisskb.ellerman.id.au/kisskb/buildresult/12358386/
---
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
index 65c532742b08d1c6..022595876ea4dc85 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
@@ -144,9 +144,8 @@ gk20a_pllg_calc_rate(struct gk20a_clk_priv *priv)
rate = priv->parent_rate * priv->n;
divider = priv->m * pl_to_div[priv->pl];
- do_div(rate, divider);
- return rate / 2;
+ return rate / divider / 2;
}
static int
--
1.9.1
Hi Geert,
On 02/05/2015 01:02 AM, Geert Uytterhoeven wrote:
> On 32-bit platforms using asm-generic/div64.h:
>
> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c: In function 'gk20a_pllg_calc_rate':
> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:79: warning: comparison of distinct pointer types lacks a cast
> do_div(rate, divider);
> ^
> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:2: warning: right shift count >= width of type
> do_div(rate, divider);
> ^
> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:238: warning: passing argument 1 of '__div64_32' from incompatible pointer type
> do_div(rate, divider);
> ^
> In file included from arch/parisc/include/generated/asm/div64.h:1:0,
> from include/linux/kernel.h:124,
> from include/linux/list.h:8,
> from include/linux/preempt.h:10,
> from include/linux/spinlock.h:50,
> from include/linux/mmzone.h:7,
> from include/linux/gfp.h:5,
> from include/linux/slab.h:14,
> from drivers/gpu/drm/nouveau/include/nvif/os.h:5,
> from drivers/gpu/drm/nouveau/include/nvkm/core/os.h:3,
> from drivers/gpu/drm/nouveau/include/nvkm/core/object.h:3,
> from drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h:3,
> from drivers/gpu/drm/nouveau/include/nvkm/subdev/clk.h:3,
> from drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:25:
> include/asm-generic/div64.h:35:17: note: expected 'uint64_t *' but argument is of type 'u32 *'
> extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
> ^
>
> do_div() is meant for 64-bit by 32-bit division, but both the dividend
> and divisor are 32-bit here. Hence use plain "/" instead.
>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> ---
> Compile-tested only.
>
> parisc/allmodconfig:
> http://kisskb.ellerman.id.au/kisskb/buildresult/12358386/
> ---
> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
> index 65c532742b08d1c6..022595876ea4dc85 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
> @@ -144,9 +144,8 @@ gk20a_pllg_calc_rate(struct gk20a_clk_priv *priv)
>
> rate = priv->parent_rate * priv->n;
> divider = priv->m * pl_to_div[priv->pl];
> - do_div(rate, divider);
>
> - return rate / 2;
> + return rate / divider / 2;
I agree there is a problem here, but considering the theoretical values
that rate can take, could we rather fix this by making rate a u64? With
the current maximum values of priv->parent_rate and priv->n, rate might
approach dangerously to the u32 limit and I believe casting it to u64
would be safer.
Hi Alexandre,
On Fri, Feb 6, 2015 at 7:50 AM, Alexandre Courbot <[email protected]> wrote:
> On 02/05/2015 01:02 AM, Geert Uytterhoeven wrote:
>> On 32-bit platforms using asm-generic/div64.h:
>> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c: In function
>> 'gk20a_pllg_calc_rate':
>> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:79: warning:
>> comparison of distinct pointer types lacks a cast
>> do_div(rate, divider);
>>
>> ^
>> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:2: warning: right
>> shift count >= width of type
>> do_div(rate, divider);
>> ^
>> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:147:238: warning: passing
>> argument 1 of '__div64_32' from incompatible pointer type
>> do_div(rate, divider);
>>
>> ^
>> In file included from arch/parisc/include/generated/asm/div64.h:1:0,
>> from include/linux/kernel.h:124,
>> from include/linux/list.h:8,
>> from include/linux/preempt.h:10,
>> from include/linux/spinlock.h:50,
>> from include/linux/mmzone.h:7,
>> from include/linux/gfp.h:5,
>> from include/linux/slab.h:14,
>> from drivers/gpu/drm/nouveau/include/nvif/os.h:5,
>> from drivers/gpu/drm/nouveau/include/nvkm/core/os.h:3,
>> from
>> drivers/gpu/drm/nouveau/include/nvkm/core/object.h:3,
>> from
>> drivers/gpu/drm/nouveau/include/nvkm/core/subdev.h:3,
>> from
>> drivers/gpu/drm/nouveau/include/nvkm/subdev/clk.h:3,
>> from drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c:25:
>> include/asm-generic/div64.h:35:17: note: expected 'uint64_t *' but
>> argument is of type 'u32 *'
>> extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
>> ^
>>
>> do_div() is meant for 64-bit by 32-bit division, but both the dividend
>> and divisor are 32-bit here. Hence use plain "/" instead.
>>
>> Signed-off-by: Geert Uytterhoeven <[email protected]>
>> ---
>> Compile-tested only.
>>
>> parisc/allmodconfig:
>> http://kisskb.ellerman.id.au/kisskb/buildresult/12358386/
>> ---
>> drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
>> b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
>> index 65c532742b08d1c6..022595876ea4dc85 100644
>> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
>> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gk20a.c
>> @@ -144,9 +144,8 @@ gk20a_pllg_calc_rate(struct gk20a_clk_priv *priv)
>>
>> rate = priv->parent_rate * priv->n;
>> divider = priv->m * pl_to_div[priv->pl];
>> - do_div(rate, divider);
>>
>> - return rate / 2;
>> + return rate / divider / 2;
>
>
> I agree there is a problem here, but considering the theoretical values that
> rate can take, could we rather fix this by making rate a u64? With the
> current maximum values of priv->parent_rate and priv->n, rate might approach
> dangerously to the u32 limit and I believe casting it to u64 would be safer.
Yes, that's better.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
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