Nouveau - Feb 2020 - [RESEND PATCH v2 9/9] ath5k: Constify ioreadX() iomem argument (as in generic implementation)

On Thu, Feb 20, 2020 at 10:48:33AM +0100, Jiri Slaby
wrote:
> On 19. 02. 20, 18:50, Krzysztof Kozlowski wrote:
> > The ioreadX() helpers have inconsistent interface.  On some
architectures
> > void *__iomem address argument is a pointer to const, on some not.
> > 
> > Implementations of ioreadX() do not modify the memory under the
address
> > so they can be converted to a "const" version for
const-safety and
> > consistency among architectures.
> > 
> > Signed-off-by: Krzysztof Kozlowski <krzk at kernel.org>
> > Acked-by: Kalle Valo <kvalo at codeaurora.org>
> > ---
> >  drivers/net/wireless/ath/ath5k/ahb.c | 10 +++++-----
> >  1 file changed, 5 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/net/wireless/ath/ath5k/ahb.c
b/drivers/net/wireless/ath/ath5k/ahb.c
> > index 2c9cec8b53d9..8bd01df369fb 100644
> > --- a/drivers/net/wireless/ath/ath5k/ahb.c
> > +++ b/drivers/net/wireless/ath/ath5k/ahb.c
> > @@ -138,18 +138,18 @@ static int ath_ahb_probe(struct platform_device
*pdev)
> >  
> >  	if (bcfg->devid >= AR5K_SREV_AR2315_R6) {
> >  		/* Enable WMAC AHB arbitration */
> > -		reg = ioread32((void __iomem *) AR5K_AR2315_AHB_ARB_CTL);
> > +		reg = ioread32((const void __iomem *) AR5K_AR2315_AHB_ARB_CTL);
> 
> While I understand why the parameter of ioread32 should be const, I
> don't see a reason for these casts on the users' side. What does it
> bring except longer code to read?
Because the argument is an int:

drivers/net/wireless/ath/ath5k/ahb.c: In function ?ath_ahb_probe?:
drivers/net/wireless/ath/ath5k/ahb.c:141:18: warning: passing argument 1 of
?ioread32? makes pointer from integer without a cast [-Wint-conversion]
   reg = ioread32(AR5K_AR2315_AHB_ARB_CTL);

Best regards,
Krzysztof

Hi Krzysztof,

On Mon, Feb 24, 2020 at 1:47 PM Krzysztof Kozlowski <krzk at kernel.org>
wrote:
> On Thu, Feb 20, 2020 at 10:48:33AM +0100, Jiri Slaby wrote:
> > On 19. 02. 20, 18:50, Krzysztof Kozlowski wrote:
> > > The ioreadX() helpers have inconsistent interface.  On some
architectures
> > > void *__iomem address argument is a pointer to const, on some
not.
> > >
> > > Implementations of ioreadX() do not modify the memory under the
address
> > > so they can be converted to a "const" version for
const-safety and
> > > consistency among architectures.
> > >
> > > Signed-off-by: Krzysztof Kozlowski <krzk at kernel.org>
> > > Acked-by: Kalle Valo <kvalo at codeaurora.org>
> > > ---
> > >  drivers/net/wireless/ath/ath5k/ahb.c | 10 +++++-----
> > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/net/wireless/ath/ath5k/ahb.c
b/drivers/net/wireless/ath/ath5k/ahb.c
> > > index 2c9cec8b53d9..8bd01df369fb 100644
> > > --- a/drivers/net/wireless/ath/ath5k/ahb.c
> > > +++ b/drivers/net/wireless/ath/ath5k/ahb.c
> > > @@ -138,18 +138,18 @@ static int ath_ahb_probe(struct
platform_device *pdev)
> > >
> > >     if (bcfg->devid >= AR5K_SREV_AR2315_R6) {
> > >             /* Enable WMAC AHB arbitration */
> > > -           reg = ioread32((void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> > > +           reg = ioread32((const void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> >
> > While I understand why the parameter of ioread32 should be const, I
> > don't see a reason for these casts on the users' side. What
does it
> > bring except longer code to read?
>
> Because the argument is an int:
>
> drivers/net/wireless/ath/ath5k/ahb.c: In function ?ath_ahb_probe?:
> drivers/net/wireless/ath/ath5k/ahb.c:141:18: warning: passing argument 1 of
?ioread32? makes pointer from integer without a cast [-Wint-conversion]
>    reg = ioread32(AR5K_AR2315_AHB_ARB_CTL);
That's an argument for keeping the cast to "void __iomem *", not
for
adding the "const", right?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at
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

From: Geert Uytterhoeven
> Sent: 24 February 2020 12:54
> To: Krzysztof Kozlowski <krzk at kernel.org>
...
> > > > diff --git a/drivers/net/wireless/ath/ath5k/ahb.c
b/drivers/net/wireless/ath/ath5k/ahb.c
> > > > index 2c9cec8b53d9..8bd01df369fb 100644
> > > > --- a/drivers/net/wireless/ath/ath5k/ahb.c
> > > > +++ b/drivers/net/wireless/ath/ath5k/ahb.c
> > > > @@ -138,18 +138,18 @@ static int ath_ahb_probe(struct
platform_device *pdev)
> > > >
> > > >     if (bcfg->devid >= AR5K_SREV_AR2315_R6) {
> > > >             /* Enable WMAC AHB arbitration */
> > > > -           reg = ioread32((void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> > > > +           reg = ioread32((const void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> > >
> > > While I understand why the parameter of ioread32 should be const,
I
> > > don't see a reason for these casts on the users' side.
What does it
> > > bring except longer code to read?
> >
> > Because the argument is an int:
> >
> > drivers/net/wireless/ath/ath5k/ahb.c: In function ?ath_ahb_probe?:
> > drivers/net/wireless/ath/ath5k/ahb.c:141:18: warning: passing argument
1 of ?ioread32? makes pointer
> from integer without a cast [-Wint-conversion]
> >    reg = ioread32(AR5K_AR2315_AHB_ARB_CTL);
> 
> That's an argument for keeping the cast to "void __iomem *",
not for
> adding the "const", right?
Or more likely change the definitions to use a struct for the layout.
That also stops the constants being used in the wrong place.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)

On Mon, Feb 24, 2020 at 01:54:00PM +0100, Geert Uytterhoeven
wrote:
> Hi Krzysztof,
> 
> On Mon, Feb 24, 2020 at 1:47 PM Krzysztof Kozlowski <krzk at
kernel.org> wrote:
> > On Thu, Feb 20, 2020 at 10:48:33AM +0100, Jiri Slaby wrote:
> > > On 19. 02. 20, 18:50, Krzysztof Kozlowski wrote:
> > > > The ioreadX() helpers have inconsistent interface.  On some
architectures
> > > > void *__iomem address argument is a pointer to const, on
some not.
> > > >
> > > > Implementations of ioreadX() do not modify the memory under
the address
> > > > so they can be converted to a "const" version for
const-safety and
> > > > consistency among architectures.
> > > >
> > > > Signed-off-by: Krzysztof Kozlowski <krzk at
kernel.org>
> > > > Acked-by: Kalle Valo <kvalo at codeaurora.org>
> > > > ---
> > > >  drivers/net/wireless/ath/ath5k/ahb.c | 10 +++++-----
> > > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/net/wireless/ath/ath5k/ahb.c
b/drivers/net/wireless/ath/ath5k/ahb.c
> > > > index 2c9cec8b53d9..8bd01df369fb 100644
> > > > --- a/drivers/net/wireless/ath/ath5k/ahb.c
> > > > +++ b/drivers/net/wireless/ath/ath5k/ahb.c
> > > > @@ -138,18 +138,18 @@ static int ath_ahb_probe(struct
platform_device *pdev)
> > > >
> > > >     if (bcfg->devid >= AR5K_SREV_AR2315_R6) {
> > > >             /* Enable WMAC AHB arbitration */
> > > > -           reg = ioread32((void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> > > > +           reg = ioread32((const void __iomem *)
AR5K_AR2315_AHB_ARB_CTL);
> > >
> > > While I understand why the parameter of ioread32 should be const,
I
> > > don't see a reason for these casts on the users' side.
What does it
> > > bring except longer code to read?
> >
> > Because the argument is an int:
> >
> > drivers/net/wireless/ath/ath5k/ahb.c: In function ?ath_ahb_probe?:
> > drivers/net/wireless/ath/ath5k/ahb.c:141:18: warning: passing argument
1 of ?ioread32? makes pointer from integer without a cast [-Wint-conversion]
> >    reg = ioread32(AR5K_AR2315_AHB_ARB_CTL);
> 
> That's an argument for keeping the cast to "void __iomem *",
not for
> adding the "const", right?
Yes, correct. Maybe I misunderstood the question... The const on the
other hand does not have to be in the cast. It is merely for making it
consistent with interface. It is not required. I also mentioned it in
the cover letter:
"PAtches 5-9 are optional cleanup, without actual impact"

Feel free to ignore this one if it is not worth the effort.

Best regards,
Krzysztof