Generic implementations of fb_pgprotect() and fb_is_primary_device()
have been in the source code for a long time. Prepare the header file
to make use of them.
Improve the code by using an inline function for fb_pgprotect()
and by removing include statements. The default mode set by
fb_pgprotect() is now writecombine, which is what most platforms
want.
Symbols are protected by preprocessor guards. Architectures that
provide a symbol need to define a preprocessor token of the same
name and value. Otherwise the header file will provide a generic
implementation. This pattern has been taken from <asm/io.h>.
v2:
* use writecombine mappings by default (Arnd)
Signed-off-by: Thomas Zimmermann <[email protected]>
---
include/asm-generic/fb.h | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/fb.h b/include/asm-generic/fb.h
index f9f18101ed36..631d97c507ca 100644
--- a/include/asm-generic/fb.h
+++ b/include/asm-generic/fb.h
@@ -1,13 +1,32 @@
/* SPDX-License-Identifier: GPL-2.0 */
+
#ifndef __ASM_GENERIC_FB_H_
#define __ASM_GENERIC_FB_H_
-#include <linux/fb.h>
-#define fb_pgprotect(...) do {} while (0)
+/*
+ * Only include this header file from your architecture's <asm/fb.h>.
+ */
+
+#include <asm/page.h>
+
+struct fb_info;
+struct file;
+
+#ifndef fb_pgprotect
+#define fb_pgprotect fb_pgprotect
+static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
+ unsigned long off)
+{
+ vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
+}
+#endif
+#ifndef fb_is_primary_device
+#define fb_is_primary_device fb_is_primary_device
static inline int fb_is_primary_device(struct fb_info *info)
{
return 0;
}
+#endif
#endif /* __ASM_GENERIC_FB_H_ */
--
2.40.0
On Thu, Apr 6, 2023, at 16:30, Thomas Zimmermann wrote:
> Generic implementations of fb_pgprotect() and fb_is_primary_device()
> have been in the source code for a long time. Prepare the header file
> to make use of them.
>
> Improve the code by using an inline function for fb_pgprotect()
> and by removing include statements. The default mode set by
> fb_pgprotect() is now writecombine, which is what most platforms
> want.
>
> Symbols are protected by preprocessor guards. Architectures that
> provide a symbol need to define a preprocessor token of the same
> name and value. Otherwise the header file will provide a generic
> implementation. This pattern has been taken from <asm/io.h>.
>
> v2:
> * use writecombine mappings by default (Arnd)
>
> Signed-off-by: Thomas Zimmermann <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Hi Thomas,
On Thu, Apr 6, 2023 at 4:30 PM Thomas Zimmermann <[email protected]> wrote:
> Generic implementations of fb_pgprotect() and fb_is_primary_device()
> have been in the source code for a long time. Prepare the header file
> to make use of them.
>
> Improve the code by using an inline function for fb_pgprotect()
> and by removing include statements. The default mode set by
> fb_pgprotect() is now writecombine, which is what most platforms
> want.
>
> Symbols are protected by preprocessor guards. Architectures that
> provide a symbol need to define a preprocessor token of the same
> name and value. Otherwise the header file will provide a generic
> implementation. This pattern has been taken from <asm/io.h>.
>
> v2:
> * use writecombine mappings by default (Arnd)
>
> Signed-off-by: Thomas Zimmermann <[email protected]>
Thanks for your patch!
> --- a/include/asm-generic/fb.h
> +++ b/include/asm-generic/fb.h
> @@ -1,13 +1,32 @@
> /* SPDX-License-Identifier: GPL-2.0 */
> +
> #ifndef __ASM_GENERIC_FB_H_
> #define __ASM_GENERIC_FB_H_
> -#include <linux/fb.h>
>
> -#define fb_pgprotect(...) do {} while (0)
> +/*
> + * Only include this header file from your architecture's <asm/fb.h>.
> + */
> +
> +#include <asm/page.h>
> +
> +struct fb_info;
> +struct file;
> +
> +#ifndef fb_pgprotect
> +#define fb_pgprotect fb_pgprotect
> +static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
> + unsigned long off)
Does this affect any noMMU platforms that relied on fb_pgprotect()
doing nothing before?
Perhaps the body below should be protected by "#ifdef CONFIG_MMU"?
> +{
> + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
Shouldn't this use the pgprot_val() wrapper?
> +}
> +#endif
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
Hi Geert
Am 11.04.23 um 10:08 schrieb Geert Uytterhoeven:
> Hi Thomas,
>
> On Thu, Apr 6, 2023 at 4:30 PM Thomas Zimmermann <[email protected]> wrote:
>> Generic implementations of fb_pgprotect() and fb_is_primary_device()
>> have been in the source code for a long time. Prepare the header file
>> to make use of them.
>>
>> Improve the code by using an inline function for fb_pgprotect()
>> and by removing include statements. The default mode set by
>> fb_pgprotect() is now writecombine, which is what most platforms
>> want.
>>
>> Symbols are protected by preprocessor guards. Architectures that
>> provide a symbol need to define a preprocessor token of the same
>> name and value. Otherwise the header file will provide a generic
>> implementation. This pattern has been taken from <asm/io.h>.
>>
>> v2:
>> * use writecombine mappings by default (Arnd)
>>
>> Signed-off-by: Thomas Zimmermann <[email protected]>
>
> Thanks for your patch!
>
>> --- a/include/asm-generic/fb.h
>> +++ b/include/asm-generic/fb.h
>> @@ -1,13 +1,32 @@
>> /* SPDX-License-Identifier: GPL-2.0 */
>> +
>> #ifndef __ASM_GENERIC_FB_H_
>> #define __ASM_GENERIC_FB_H_
>> -#include <linux/fb.h>
>>
>> -#define fb_pgprotect(...) do {} while (0)
>> +/*
>> + * Only include this header file from your architecture's <asm/fb.h>.
>> + */
>> +
>> +#include <asm/page.h>
>> +
>> +struct fb_info;
>> +struct file;
>> +
>> +#ifndef fb_pgprotect
>> +#define fb_pgprotect fb_pgprotect
>> +static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
>> + unsigned long off)
>
> Does this affect any noMMU platforms that relied on fb_pgprotect()
> doing nothing before?
> Perhaps the body below should be protected by "#ifdef CONFIG_MMU"?
I cannot conclusively answer this question, but I did some grep'ing
('git grep ndef | grep CONFIG_MMU'):
Only the architectures in this patchset provide <asm/fb.h> but nothing
anywhere uses <asm-generic/fb.h> yet. And of those architectures, only
arm and m68k have !CONFIG_MMU cases. Those are handled in the rsp
patches. I think we're good.
>
>> +{
>> + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
>
> Shouldn't this use the pgprot_val() wrapper?
No, I think. Grep'ing for vm_page_prot, I'm not seeing it being used in
such assignments.
Best regards
Thomas
>
>> +}
>> +#endif
>
> Gr{oetje,eeting}s,
>
> Geert
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
On Mon, Apr 17, 2023, at 11:03, Thomas Zimmermann wrote:
> Am 11.04.23 um 10:08 schrieb Geert Uytterhoeven:
>> On Thu, Apr 6, 2023 at 4:30 PM Thomas Zimmermann <[email protected]> wrote:
>>> +#ifndef fb_pgprotect
>>> +#define fb_pgprotect fb_pgprotect
>>> +static inline void fb_pgprotect(struct file *file, struct vm_area_struct *vma,
>>> + unsigned long off)
>>
>> Does this affect any noMMU platforms that relied on fb_pgprotect()
>> doing nothing before?
>> Perhaps the body below should be protected by "#ifdef CONFIG_MMU"?
>
> I cannot conclusively answer this question, but I did some grep'ing
> ('git grep ndef | grep CONFIG_MMU'):
>
> Only the architectures in this patchset provide <asm/fb.h> but nothing
> anywhere uses <asm-generic/fb.h> yet. And of those architectures, only
> arm and m68k have !CONFIG_MMU cases. Those are handled in the rsp
> patches. I think we're good.
Agreed. The generic version is just a more elaborate way to do
nothing here, as the
vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
line on nommu just turns into a self-assignment of the same member
that was set the line before.
Arnd